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Network Working Group D. Mitzel Request for Comments: 3002 Nokia Category: Informational December 2000

       Overview of 2000 IAB Wireless Internetworking Workshop

Status of this Memo

 This memo provides information for the Internet community.  It does
 not specify an Internet standard of any kind.  Distribution of this
 memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (2000).  All Rights Reserved.

Abstract

 This document provides an overview of a workshop held by the Internet
 Architecture Board (IAB) on wireless internetworking.  The workshop
 was hosted by Nokia in Mountain View, CA, USA on February 29 thru
 March 2, 2000.  The goal of the workshop was to assess current and
 future uses of Internet technology in wireless environments, to make
 recommendations on research and standardization tasks to improve
 acceptance of Internet network and transport protocols in wireless
 environments, and to evaluate methods to improve communication and
 collaboration among Internet standards working groups and those of
 the telephony and wireless sectors.  This report summarizes the
 conclusions and recommendations of the IAB on behalf of the IETF
 community.
 Comments should be submitted to the IAB-Wireless-Workshop@ietf.org
 mailing list.

Table of Contents

 1      Introduction  . . . . . . . . . . . . . . . . . . . .   3
 2      Presentation Overview . . . . . . . . . . . . . . . .   4
 3      Discussion and Observations . . . . . . . . . . . . .   9
 3.1    Discussion on "Walled Garden" Service Model . . . . .   9
 3.2    Discussion on Mobility and Roaming  . . . . . . . . .  10
 3.2.1  Discussion on Mobility and Roaming Model  . . . . . .  11
 3.2.2  Discussion on Mobility and Roaming Protocols  . . . .  11
 3.2.3  Discussion on Mobility and Roaming Services . . . . .  12
 3.3    Discussion on Security Model  . . . . . . . . . . . .  12
 3.3.1  Discussion on User Identity . . . . . . . . . . . . .  12
 3.3.2  Discussion on WAP Security  . . . . . . . . . . . . .  13

Mitzel Informational [Page 1] RFC 3002 IAB Wireless Workshop December 2000

 3.3.3  Discussion on 3G Network Security . . . . . . . . . .  13
 3.4    Discussion on Transports  . . . . . . . . . . . . . .  14
 3.4.1  Discussion on Link Characteristics and Mobility
        Effect on Transport . . . . . . . . . . . . . . . . .  14
 3.4.2  Discussion on WAP Transport . . . . . . . . . . . . .  16
 3.4.3  Discussion on IETF Transport Activities . . . . . . .  16
 3.5    Discussion on Aeronautical Telecommunication Network
        (ATN) Routing Policy. . . . . . . . . . . . . . . . .  17
 3.6    Discussion on QoS Services  . . . . . . . . . . . . .  18
 3.6.1  Discussion on "Last Leg" QoS  . . . . . . . . . . . .  18
 3.6.2  Discussion on Path QoS Discovery  . . . . . . . . . .  19
 3.7    Discussion on Header Compression  . . . . . . . . . .  20
 3.8    Discussion on Applications Protocols  . . . . . . . .  21
 3.9    Discussion on Proxy Agents  . . . . . . . . . . . . .  22
 3.10   Discussion on Adoption of IPv6  . . . . . . . . . . .  22
 3.11   Discussion on Signaling . . . . . . . . . . . . . . .  23
 3.12   Discussion on Interactions Between IETF and Other
        Standards Organizations . . . . . . . . . . . . . . .  24
 4      Recommendations . . . . . . . . . . . . . . . . . . .  25
 4.1    Recommendations on Fostering Interaction with Non-
        Internet Standards Organizations  . . . . . . . . . .  25
 4.2    Recommendations for Dealing with "Walled Garden"
        Model . . . . . . . . . . . . . . . . . . . . . . . .  26
 4.3    Recommendations on IPv4 and IPv6 Scaling  . . . . . .  27
 4.4    Recommendations on IPv4 and IPv6 Mobility . . . . . .  28
 4.5    Recommendations on TCP and Transport Protocols  . . .  29
 4.6    Recommendations on Routing  . . . . . . . . . . . . .  31
 4.7    Recommendations on Mobile Host QoS Support  . . . . .  32
 4.8    Recommendations on Application Mobility . . . . . . .  33
 4.9    Recommendations on TCP/IP Performance Characterization
        in WAP-like Environment . . . . . . . . . . . . . . .  33
 4.10   Recommendations on Protocol Encoding  . . . . . . . .  33
 4.11   Recommendations on Inter-Domain AAA Services  . . . .  34
 4.12   Recommendations on Bluetooth  . . . . . . . . . . . .  34
 4.13   Recommendations on Proxy Architecture . . . . . . . .  34
 4.14   Recommendations on Justifying IPv6-based Solutions for
        Mobile / Wireless Internet  . . . . . . . . . . . . .  35
 5      Security Considerations . . . . . . . . . . . . . . .  35
 6      Acknowledgments . . . . . . . . . . . . . . . . . . .  35
 7      Bibliography  . . . . . . . . . . . . . . . . . . . .  36
 A      Participants  . . . . . . . . . . . . . . . . . . . .  41
 B      Author's Address  . . . . . . . . . . . . . . . . . .  41
        Full Copyright Statement  . . . . . . . . . . . . . .  42

Mitzel Informational [Page 2] RFC 3002 IAB Wireless Workshop December 2000

1 Introduction

 Wireless technology, including wireless LANs, data transfer over
 cellular radio (GSM, 3GPP, etc), and mobile operations from aircraft
 and near earth spacecraft are becoming increasingly important.  Some
 market projections suggest that a mobile Internet in parallel with or
 augmenting the wired Internet may be comparable in size to the wired
 Internet as early as 2003.
 The wireless operators have not, however, chosen to use IPv4, TCP,
 full HTTP/HTML, and other applications for a variety of reasons.
 These relate to edge device cost, bandwidth limitations, perceived
 protocol imperfections, unnecessary complexities, the chattiness of
 the application protocols, and network layer addressing issues.
 Unfortunately, this creates some serious issues at the wired/wireless
 demarcation: end to end operation is sacrificed, security is
 compromised, and automated content modification in some form becomes
 necessary.  The IAB considers these to be serious fundamental issues,
 which will in time be a serious impediment to the usability of the
 combined Internet if not addressed.
 The Internet Architecture Board (IAB), on February 29 thru March 2,
 2000, held an invitational workshop on wireless internetworking.  The
 goal of the workshop was to assess current and future uses of
 Internet technology in wireless environments, to make recommendations
 on research and standardization tasks to improve acceptance of
 Internet network and transport protocols in wireless environments,
 and to evaluate methods to improve communication and collaboration
 among Internet standards working groups and those of the telephony
 and wireless sectors.
 The following topics were defined for discussion:
      + Local area wireless technologies
      + Cellular wireless technologies
      + Wireless Application Protocol (WAP)
      + Near-space and aviation wireless applications
      + Voice over IP (VoIP) over wireless networks
      + Security over wireless networks
      + Transport and QoS over wireless networks
      + Use of WWW protocols over wireless and small screen devices

Mitzel Informational [Page 3] RFC 3002 IAB Wireless Workshop December 2000

      + Addressing requirements for wireless devices
      + Compression and bit error requirements for wireless networks
 The fundamental question addressed in these discussion is "what are
 the issues, and what really needs to be done to unify the Internet
 below the application layer."  Applications will also need to be
 addressed, but were perceived to be more than could be usefully
 discussed in a three-day workshop, and probably require different
 expertise.
 Section 2 presents a concise overview of the individual presentations
 made during the workshop.  References to more extensive materials are
 provided.  Details on major discussion topics are provided in section
 3.  Section 4 presents the recommendations made to wireless
 operators, IRTF, and IETF on the architectural roadmap for the next
 few years.  It should be noted that not all participants agreed with
 all of the statements, and it was not clear whether anyone agreed
 with all of them.  However, the recommendations made are based on
 strong consensus among the participants.  Finally, section 5
 highlights references to security considerations discussed, appendix
 A lists contact information of workshop participants, and appendix B
 lists the author contact information.

2 Presentation Overview

    Title: Overview of Wireless IP Devices (Network Implications...)
    Presenter: Heikki Hammainen
    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/hh-IABpub.PDF,
         http://www.iab.org/IAB-wireless-workshop/talks/hh-IABpub.ppt
    Overview:
    Title: Overview of IEEE 802.11 Wireless LAN's & Issues Running IP
         over IEEE 802.11?
    Presenter: Juha Ala-Laurila
    Reference:
         http://www.iab.org/IAB-wireless-work-
         shop/talks/IEEE80211_IP.ppt
    Overview:

Mitzel Informational [Page 4] RFC 3002 IAB Wireless Workshop December 2000

    Title: Overview of Bluetooth Wireless & Issues Running IP over
         Bluetooth?
    Presenter: Pravin Bhagwat
    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/BT-
         overview.PDF,
         http://www.iab.org/IAB-wireless-workshop/talks/BT-
         overview.ppt
    Overview:
    Title: Overview of Cellular Data Systems & Approaches to more IP
         centric Cellular Data System
    Presenter: Jonne Soinien
    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/
         Cellular_JSo.PDF,
         http://www.iab.org/IAB-wireless-workshop/talks/
         Cellular_JSo.ppt
    Overview:
    Title: IP Packet Data Service over IS-95 CDMA
    Presenter: Phil Karn
    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/karn/index.htm
    Overview:
    Title: Wireless Internet Networking
    Presenter: Chih-Lin I
    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/IAB000229.PDF,
         http://www.iab.org/IAB-wireless-workshop/talks/IAB000229.ppt
    Overview:
    Title: Mobile IP in Cellular Data Systems
    Presenter: Charlie Perkins

Mitzel Informational [Page 5] RFC 3002 IAB Wireless Workshop December 2000

    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/WLIP99.PDF,
         http://www.iab.org/IAB-wireless-workshop/talks/WLIP99.ppt
    Overview:
    Title: Overview of WAP
    Presenter: Alastair Angwin
    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/iab-wap-1.pdf
    Overview:
    Title: Mobile Wireless Internet Forum (MWIF)
    Presenter: Alastair Angwin
    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/MWIF_TC
         _Presentation.PDF,
         http://www.iab.org/IAB-wireless-workshop/talks/MWIF_TC
         _Presentation.ppt
    Overview:
    Title: Some WAP History
    Presenter: Jerry Lahti
    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/waphist.PDF,
         http://www.iab.org/IAB-wireless-workshop/talks/waphist.ppt
    Overview:
    Title: Near-space Wireless Applications
    Presenter: Mark Allman
    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/allman-iab-
         wireless.pdf,
         http://www.iab.org/IAB-wireless-workshop/talks/allman-iab-
         wireless.ps
    Overview:

Mitzel Informational [Page 6] RFC 3002 IAB Wireless Workshop December 2000

    Title: Air Traffic / Aviation Wireless
    Presenter: Chris Wargo
    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/wargo-talk.PDF,
         http://www.iab.org/IAB-wireless-workshop/talks/wargo-talk.ppt
    Overview:
    Title: VoIP over Wireless
    Presenter: Christian Huitema
    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/iab-wless-
         voip.PDF,
         http://www.iab.org/IAB-wireless-workshop/talks/iab-wless-
         voip.ppt
    Overview:
    Title: Security Issues in Wireless Networks and Mobile Computing
    Presenter: N. Asokan
    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/mobile-secu-
         rity.PDF,
         http://www.iab.org/IAB-wireless-workshop/talks/mobile-secu-
         rity.ppt
    Overview:
    Title: Security for Mobile IP in 3G Networks
    Presenter: Pat Calhoun
    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/mip-sec-3g.PDF,
         http://www.iab.org/IAB-wireless-workshop/talks/mip-sec-3g.ppt
    Overview:
    Title: On Inter-layer Assumptions (A View from the Transport Area)
    Presenter: Mark Handley

Mitzel Informational [Page 7] RFC 3002 IAB Wireless Workshop December 2000

    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/handley-
         wireless.pdf,
         http://www.iab.org/IAB-wireless-workshop/talks/handley-wire-
         less.ps
    Overview:
    Title: Does current Internet Transport work over Wireless?
    Presenter: Sally Floyd
    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/IAB-wireless-
         Mar00.pdf,
         http://www.iab.org/IAB-wireless-workshop/talks/IAB-wireless-
         Mar00.ps
    Overview:
    Title: QOS for Wireless (DiffServ, IntServ, other?)
    Presenter: Lixia Zhang
    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/zhang-feb-
         IAB.PDF,
         http://www.iab.org/IAB-wireless-workshop/talks/zhang-feb-
         IAB.ppt
    Overview:
    Title: Do current WWW Protocols work over Wireless and Small
         Screen Devices?
    Presenter: Gabriel Montenegro
    Reference:
          http://www.iab.org/IAB-wireless-workshop/talks/wireless-
          www.PDF,
          http://www.iab.org/IAB-wireless-workshop/talks/wireless-
          www.ppt
    Overview:
    Title: Compression & Bit Error Requirements for Wireless
    Presenter: Mikael Degermark

Mitzel Informational [Page 8] RFC 3002 IAB Wireless Workshop December 2000

    Reference:
         http://www.iab.org/IAB-wireless-workshop/talks/iab-hc.PDF,
         http://www.iab.org/IAB-wireless-workshop/talks/iab-hc.ppt
    Overview:
    Title: Addressing Requirements for Wireless Devices & IPv6
    Presenter: Bob Hinden
    Reference:
          http://www.iab.org/IAB-wireless-workshop/talks/Addressing-
          IPv6.PDF,
          http://www.iab.org/IAB-wireless-workshop/talks/Addressing-
          IPv6.ppt
     Overview:

3 Discussion and Observations

 During the workshop presentations a number of issues were discussed
 and observations made.  The following sections 3.1 -- 3.12 summarize
 these discussion and observations.  Rather than organizing the
 material linearly by presentation, it is grouped according to common
 "themes" and issues.

3.1 Discussion on "Walled Garden" Service Model

 Presentations from members involved in the cellular wireless (3GPP,
 3G.IP, MWIF) and WAP environments quickly illustrated a significant
 difference in protocol specification and service models from that
 typically assumed by the Internet community.  These communities focus
 on defining a profile (set of protocols and operational parameters)
 that combine to provide a well defined user service.  In addition,
 the carriers typically prefer to have complete (or as much as
 possible) control over the entire service, including user access
 device, transmission facilities, and service "content".  This style
 of service model appears to have been inherited from the classic
 telephony provider model.  The term "walled garden" was coined to
 describe the resulting captive customer economic and service model.
 That is, the user is constrained within the limits of the service
 provided by the carrier with limited ability to extend features or
 access services outside the provider.           The "walled garden"
 service model is in stark contrast to the "open" service assumed in
 the Internet.  The application, access device, and service content
 may each be controlled by a different entity, and the service
 provider is typically viewed as little more than a "bit pipe".

Mitzel Informational [Page 9] RFC 3002 IAB Wireless Workshop December 2000

 Additionally, specification typically define a standalone protocol or
 application rather than the set of features and interoperation with
 other components required to deploy a commercial service.
 Some discussion focused on whether cellular carriers could be
 persuaded to transition toward the Internet "open" service model.
 Responses indicated that there was little hope of this as carriers
 will always fight being reduced to a "bit pipe", fearing they cannot
 sustain sufficient revenues without the value added services.  An
 additional point raised was that the closed model of the "walled
 garden" simplifies a number of issues, such as security,
 authorization, and billing when the entire network is considered
 secured and controlled under a single administration.  These
 simplification can eliminate roadblocks to service deployment before
 scalable, interdomain solutions are available.
 Even though there seems little hope of evolving carriers away from
 the "walled garden" service in the short term, there was significant
 value in recognizing its presence.  This led to observations that
 "walled garden" Internet-based services will operate somewhat like
 current intranet services.  Also, mechanisms should be investigated
 to simplify interoperation and controlled access to the Internet.
 Finally, the difference between Internet protocol specification
 contrasted to service profiles highlights some of the confusion those
 in the telephony environment encounter when attempting to incorporate
 Internet capabilities.
 Much of the current work in extending Internet-based services to
 cellular customers has focused on data services such as email or web
 access.  One observation on the reluctance of carriers to release any
 control over services was that this may be an impediment to adoption
 of Internet-based voice services.  Current work on voice over IP
 (VoIP) and call signaling (SIP [30]) loosens control over these
 services, much of the functionality is moved into the SIP agent with
 the carrier being reduced to an access provider (i.e., "bit pipe").

3.2 Discussion on Mobility and Roaming

 An inherent characteristic of wireless systems is their potential for
 accommodating device roaming and mobility.  Some discussion focused
 on the model of mobility presented to the user.  There was also
 considerable interest and discussion on protocols employed, using
 cellular telephony and/or IP-based solutions.  Finally, there was
 some interest in exploring new services enabled by mobility.

Mitzel Informational [Page 10] RFC 3002 IAB Wireless Workshop December 2000

3.2.1 Discussion on Mobility and Roaming Model

 There was considerable discussion and concern over what style of
 mobility and roaming needs to be supported.  Current usage in the
 Internet is dominated by the mode where a user performs some actions
 at one location, then shuts down and moves, followed by restart at a
 new location.
 3G.IP uses the term "macro mobility" to describe this mode.
 The discussion attempted to discern whether the current mode of usage
 is a perceived limitation introduced by current protocols.  A clear
 consensus could not be achieved.  There was agreement that
 introduction of this "macro mobility" roaming is a worthwhile first
 step.  However, that was immediately followed by questions on whether
 it is a sufficient first step, and warning not to stop at this level.
 There seems significant issues for continued investigation related to
 enabling continual usage of a device during roaming ("micro
 mobility") and the ability to retrieve previous connections after a
 roaming event.

3.2.2 Discussion on Mobility and Roaming Protocols

 Selection between cellular and IP protocols in support of roaming
 provided another topic for significant discussion.  Cellular
 operators have already deployed protocols providing significant
 support for roaming.  This has led several efforts, such as 3GPP and
 3G.IP, toward architecture relying on telephone system for all
 mobility support, hiding roaming from the IP layer.
 Arguments for cellular-based roaming centered on concerns about the
 mobile IP model.  There was concern that home agent and foreign agent
 involvement in delivery might introduce bottleneck, and the
 perception that mobile IP handoff is too slow.  A rebuttal offered
 was that IETF mobileip working group is introducing hierarchy and
 route optimization to improve performance and robustness [50], and
 there was disagreement on the point regarding slow handoff under
 mobile IP.
 Detriments to the cellular-based roaming include the lack of IP
 support out to the mobile device and the added tunneling protocols
 and overhead required.  Additionally, roaming is less well defined
 when traversing service provider boundaries and may involve highly
 non-optimal forwarding path.  There appears significant work
 remaining to reach convergence on opinions, and additional
 investigation to support roaming across cellular, WLAN, and IP
 boundaries.

Mitzel Informational [Page 11] RFC 3002 IAB Wireless Workshop December 2000

3.2.3 Discussion on Mobility and Roaming Services

 3G.IP mobility model is primarily focused on providing ubiquitous
 service across a range of access media.  However, the presentation
 also highlighted a desire to develop new "location based" services.
 Examples presented include locating nearby services or receiving
 advertisement and solicitations from nearby business.
 There are several Internet protocols defined, such as anycast service
 [47] and SLP [28], that may aid in developing location based
 services.  However, there was considerable frustration on the part of
 3G.IP in that there appears little commercial support of these
 protocols, and even less direction on how to assemble and coordinate
 the required protocols to deploy the desired services.
 This exchange illustrated the disconnect between interpreting
 Internet standards and telephony service profiles.  First, in the
 Internet many protocols are defined but many are optional.  Protocol
 support is typically driven by market demand, which can lead to
 "chicken and egg" problem.  Secondly, individual protocols and
 applications are developed rather than complete profile to compose a
 commercial service.  For this service, evaluating the usage and
 scalability of service discovery protocols appears to be an area open
 for further investigation.

3.3 Discussion on Security Model

 Mobility and wireless environments introduce many complexities and
 potential attacks to user authentication and privacy.  In addition to
 the discussion presented below, there was an overriding statement
 made regarding the methodology that must be followed for all security
 protocol development.  It was felt quite strongly that the only
 chance for success is that the definition be done in a public forum,
 allowing full disclosure of all algorithms and thorough review by
 security experts.  Stated an alternate way, defining protocols in a
 closed forum relying on cellphone manufacturers, or other non-experts
 on IP security, is very likely to create security exposures.

3.3.1 Discussion on User Identity

 Storage of user identity can have significant effect on device usage
 and device portability.  Discussion focused on whether identity
 should be tied to the mobile device or a transferable SIM card.
 Fixing identification with the device may simplify manufacture and
 provide some tamper resistance, however it makes it very difficult to
 deploy a public device taking on the identity of the user.  These
 alternative also affect transfer of identity and configuration state
 on device replacement or upgrade.

Mitzel Informational [Page 12] RFC 3002 IAB Wireless Workshop December 2000

 A related topic revolves around the user desire to employ a single
 device but to take on a different identity and privilege based on the
 usage at hand (e.g., to gain corporate access, home access, or
 Internet access).  The ability and ease of assuming these multiple
 identities may be highly dependent on the model of identity
 integration, as discussed above.  Discussion highlighted potential
 pitfalls based on tieing of device and user identities.  IPsec use of
 device IP address inhibits roaming capabilities as the address may
 change based on location, and precludes distinguishing identity and
 capabilities for current usage.  IPsec requires additional work to
 accommodate this added flexibility.
 A final topic of discussion on user identity establishment was
 whether possession of the device is sufficient, or whether the user
 should be required to authenticate to the device.  In the real world
 the first alternative is exemplified by the credit card model, while
 the second is more analogous to the ATM card where the user must also
 provide a PIN code.  Both models seem useful in the real world, and
 it's likely both will have uses in wireless networking.

3.3.2 Discussion on WAP Security

 WAP wireless transport security (WTLS) is based on TLS [20], with
 optimized handshake to allow frequent key exchange.  The security
 service employs a "vertical" integration model, with protocol
 components throughout the network stack.  Some argued that this is
 the wrong model.  A better approach may have been a security layer
 with well defined interfaces.  This could allow for later tradeoffs
 among different protocols, driven by market, applications, and device
 capabilities.
 Additional statements argued that the WAP security model illustrates
 dangers from optimizing for a limited usage domain ("walled garden").
 Content provider systems requiring security (e.g., banks) must deploy
 a special WAP proxy, which breaks the model of a single WAP "domain".
 Similar issues are inherent in gatewaying to the Internet.

3.3.3 Discussion on 3G Network Security

 The existing GSM/GPRS model uses long term shared secrets (embedded
 in SIM card) with one-way authentication to the network, and with
 privacy only provided on the access link.  This is an example where
 the "walled garden" service model has an advantage.  Complete control
 over the service access devices and network greatly reduces the range
 of security concerns and potential attacks.

Mitzel Informational [Page 13] RFC 3002 IAB Wireless Workshop December 2000

 Future 3GPP and 3GPP2 plan to push IP all the way out to the wireless
 device.  An observation is that this results in more potential for
 exposure of signaling and control plane to attacks.  Desire is to
 perform mutual authentication and securing of the network.  This is a
 difficult problem with additional issues remaining to be solved;
 however the statement was made that relying on IP and open standards
 is more likely to produce a provably secure network than former
 reliance on SS7 protocols and obscurity.
 Completing support for the security requirements of the 3GPP/3GPP2
 network seems to require resolving issues in two primary areas, AAA
 services and mobile IP.  AAA is required for authentication,
 authorization, and billing.  Remaining issues center around cross
 domain AAA, authentication using PKI, and there was considerable
 aversion to use of IPsec and IKE protocols due to perceived overhead
 and delay.  Mobile IP issues revolve around solutions to reduce the
 security associations required between mobile node and home agent,
 mobile node and foreign agent, and the home and foreign agent.  An
 interim solution being investigated involves use of a RADIUS server
 [56]; however, there are concerns with repeated dynamic key
 generation on each handoff or hiding some details of handoffs, which
 may violate assumptions in mobile IP protocol [48].  Evaluating
 requirements and addressing all of these open issues appears to be an
 excellent opportunity for mutual cooperation on open standardization
 and review.

3.4 Discussion on Transports

 Discussion on transport protocols touched on a broad range of issues.
 Concerns ranged from the effects of wireless link characteristics and
 mobility effect on TCP, to development of new transport protocols
 such as WAP Wireless Transaction Protocol (WTP).  In addition, a
 significant amount of time was spent reviewing ongoing efforts within
 the IETF on TCP transport enhancements and investigation of new
 transports.

3.4.1 Discussion on Link Characteristics and Mobility Effect on

    Transport
 TCP makes assumptions on loss as congestion indication.  The
 statement was made that TCP was designed for links with about 1%
 corruption loss, and provided that constraint is met then TCP should
 function properly.  Presentation on IS-95 CDMA-based data service
 showed that it conditions line to provide 1--2% error rate with
 little correlation between loss.  Similar conditioning and Forward
 Error Correction (FEC) mechanisms may be appropriate for other
 wireless and satellite systems [4].  This may not be true for all
 wireless media, but it was interesting in the fact that it indicates

Mitzel Informational [Page 14] RFC 3002 IAB Wireless Workshop December 2000

 TCP should work properly on many wireless media.  However, the amount
 of discussion and suggestions on TCP performance optimizations showed
 that there can be a considerable gap between merely working and
 working well.
 One issue raised several times was related to the effects of non-
 congestive loss on TCP performance.  In the wireless environment
 non-congestive loss may be more prevalent due to corruption loss
 (especially if the wireless link cannot be conditioned to properly
 control error rate) or an effect of mobility (e.g., temporary outage
 while roaming through an area of poor coverage).  These losses can
 have great detrimental effect on TCP performance, reducing the
 transmission window and halving the congestion window size.  Much of
 the discussion focused on proposing mechanisms to explicitly indicate
 a non-congestive loss to the TCP source.  Suggestions included a
 Non-Congestive Loss Indication (NCLI) sent for instance when packet
 corruption loss is detected, or sending a Source Encourage (SE) to
 stimulate source transmission at the end of an outage.  In addition
 to data corruption, wireless links can also experience dropouts.  In
 this situation any active TCP sessions will commence periodic
 retransmissions, using an exponentially increasing back-off timer
 between each attempt.  When the link becomes available it may be many
 seconds before the TCP sessions resume transmission.  Mechanisms to
 alleviate this problem, including packet caching and triggered
 retransmission were discussed.  The more generic form of all of these
 mechanisms is one that allows the state of the layer two (datalink)
 system to signal to the TCP session its current operating mode.
 Developing a robust form of such a signaling mechanism, and
 integrating these signals into the end-to-end TCP control loop may
 present opportunities to improve TCP transport efficiency for
 wireless environments.
 TCP improvements have been incorporated to support "long" links
 (i.e., those with large delay and bandwidth characteristics) [36],
 however considerable expertise may still be required to tune socket
 buffers for maximum performance.  Some work has been done on auto-
 tuning buffers, which shows promise [58].  An additional problem with
 large windows and auto-tuning is the added header overheads.  This
 may exasperate the problems of running TCP over low bandwidth links.
 Suggestions included to explore dynamic negotiation of large window
 extensions in the middle of a connection to alleviate these issues.
 A final issue raised with regardport (see discussion below in section
 3.4.3).
 There was also concern regarding mobility effects on TCP performance.
 TCP has implicit assumptions on bounding propagation delay.  If delay
 exceeds the smoothed round trip time plus four times the round trip
 variance then the segment is considered lost, triggering the normal

Mitzel Informational [Page 15] RFC 3002 IAB Wireless Workshop December 2000

 backoff procedures.  Could these assumptions be violated by segment
 loss or duplication during handoff? Work on D-SACK [25] may alleviate
 these worries, detecting reordering and allowing for adaptive DUP-ACK
 threshold.  Finally, there was suggestion it might be appropriate to
 adapt (i.e., trigger slow start) immediately after mobile handoff on
 the assumption that path characteristics may differ.

3.4.2. Discussion on WAP Transport

 WAPF considered TCP connection setup and teardown too expensive in
 terms of bit overhead and latency when required for every
 transaction.  WAPF developed the Wireless Transaction Protocol (WTP),
 with some inspiration from T/TCP [12].  WTP offers several classes of
 service ranging from unconfirmed request to single request with
 single reply transaction.  Data is carried in the first packet and
 3-way handshake eliminated to reduce latencies.  In addition
 acknowledgments, retransmission, and flow control are provided.
 Discussion on WTP centered on assessing details on its operation.
 Although it incorporates mechanisms for reliability and flow control
 there was concern that it may miss critical or subtle transport
 issues learned through years of Internet research and deployment
 experience.  One potential area for disaster appeared to be the use
 of fixed retransmission timers and lack of congestion control.  This
 gave rise to suggestions that the IETF write up more details on the
 history and tradeoffs in transport design to aid others doing
 transport design work, and secondly that the IETF advocate that the
 congestion control is not optional when using rate adaptive transport
 protocols.
 The remaining discussion on WAP transport primarily focused on ways
 to share information.  It was suggested that any result from WAPF
 study of TCP shortcomings that led to its rejection might be useful
 for IETF review as inputs for TCP modifications.  Similar comments
 were raised on study of T/TCP shortcomings and its potential exposure
 to Denial of Service (DoS) attacks.  It was also encouraged that the
 WAPF members participate in the IETF directly contribute requirements
 and remain abreast of current efforts on evolving TCP operation and
 introduction of new transport (see discussion below in section
 3.4.3.).

3.4.3 Discussion on IETF Transport Activities

 Discussion on transport work in the IETF presented a large array of
 activities.  Recent work on transport improvement includes path MTU,
 Forward Error Correction (FEC), large windows, SACK, NewReno Fast
 Recovery, ACK congestion control, segment byte counting, Explicit
 Congestion Notification (ECN), larger initial transmit windows, and

Mitzel Informational [Page 16] RFC 3002 IAB Wireless Workshop December 2000

 sharing of related TCP connection state [3,4,5,6,24,25,43,53,63].
 Work on new transports includes SCTP [61] in the IETF Signaling
 Transport (sigtran) working group and TCP-Friendly Rate Control
 (TFRC) [1] by researchers at ACIRI.  SCTP provides a reliable UDP-
 like protocol supporting persistent associations and in-order
 delivery with congestion control.  TFRC is targeted at unreliable,
 unicast streaming media.  Finally, work in the IETF End-point
 Congestion Management (ecm) working group is looking at standardizing
 congestion control algorithms, and work in the Performance
 Implications of Link Characteristics (pilc) working group is
 characterizing performance impacts of various link technologies and
 investigating performance improvements.
 This vast array of ongoing research and standards development seemed
 a bit overwhelming, and there was considerable disagreement on the
 performance and applicability of several TCP extensions.  However,
 this discussion did raise a couple of key points.  First, transport
 work within the Internet community is not stagnant, there is a
 significant amount of interest and activity in improvement to
 existing protocols and exploration of new protocols.  Secondly, the
 work with researchers in satellite networking has demonstrated the
 tremendous success possible in close collaboration.  The satellite
 networking community was dissatisfied with initial TCP performance on
 long delay links.  Through submission of requirements and
 collaborative investigation a broad range of improvements have been
 proposed and standardized to address unique characteristics of this
 environment.  This should hopefully set a very positive precedent to
 encourage those in the wireless sector to pursue similar
 collaboration in adoption of Internet protocols to their environment.

3.5 Discussion on Aeronautical Telecommunication Network (ATN) Routing

  Policy
 The Aeronautical Telecommunication Network (ATN) has goals to improve
 and standardize communications in the aviation industry.  This ranges
 across air traffic management and control, navigation and
 surveillance, all the way up to passenger telephone service and
 entertainment.  This also involves integration of both fixed ground
 segments and mobile aircraft.  Supporting the ATN architecture using
 Internet protocols may introduce additional requirements on the
 routing infrastructure.
 Current ATN views each aircraft as an autonomous network (AS) with
 changing point of attachment as it "roams" through different
 airspace.  Addressing information associated with the aircraft is
 fixed, which makes route aggregation difficult since they're not
 related to topology, and also increases the frequency of updates.
 Additionally, the aircraft may be multiply attached (within coverage

Mitzel Informational [Page 17] RFC 3002 IAB Wireless Workshop December 2000

 of multiple ground and space-based access networks), requiring
 routing policy support for path selection.  Finally, QoS path
 selection capabilities may be beneficial to arbitrate shared access
 or partition real-time control traffic from other data traffic.
 Initial prototype of ATN capabilities have been based on ISO IDRP
 [33] path selection and QoS routing policy.  There was some
 discussion whether IDRP could be adopted for use in an IP
 environment.  There was quick agreement that the preferred solution
 within the IETF would be to advance BGP4++ [8,54] as an IDRP-like
 replacement.  This transitioned discussion to evaluation of ATN use
 of IDRP features and their equivalent to support in BGP.  Several
 issues with BGP were raised for further investigation.  For example,
 whether BGP AS space is sufficient to accommodate each aircraft as an
 AS? Also issues with mobility support; can BGP provide for
 dynamically changing peering as point of attachment changes, and
 alternative path selection policies based on current peerings? A
 significant amount of additional investigation is required to fully
 assess ATN usage of IDRP features, especially in the QoS area.  These
 could lead to additional BGP requirements, for instance to effect
 different prioritization or path selection for aircraft control vs.
 passenger entertainment traffic.

3.6 Discussion on QoS Services

 Enabling support for voice and other realtime services along with
 data capabilities requires Quality of Service (QoS) features to
 arbitrate access to the limited transmission resources in wireless
 environment.  The wireless and mobile environment requires QoS
 support for the last leg between the mobile device and network access
 point, accommodating roaming and unique characteristics of the
 wireless link.
 In addition to the discussion presented below, it was felt quite
 strongly that it is critical any QoS facility be provided as an
 underlying service independent of payload type.  That is, there
 should be no built in knowledge of voice or other application
 semantics.  This results in a feature that can be leveraged and
 easily extended to support new applications.

3.6.1 Discussion on "Last Leg" QoS

 Discussion on voice over IP (VoIP) emphasized that (wireless) access
 link is typically the most constrained resource, and while contention
 access (CSMA) provides good utilization for data it is not ideal for
 voice.  Two models were identified as potential solution in VoIP
 architecture.  The first is to have the wireless device directly
 signal the local access router.  A second alternative is to have the

Mitzel Informational [Page 18] RFC 3002 IAB Wireless Workshop December 2000

 call control element (SIP agent [30]) "program" the edge router.
 This tradeoff seemed to be an area open for additional investigation,
 especially given the complications that may be introduced in the face
 of mobility and roaming handoffs.  This appears a key component to
 solve for success in VoIP adoption.
 Work within the IEEE 802.11 WLAN group identified similar
 requirements for QoS support.  That group is investigating a model
 employing two transmission queues, one for realtime and one for
 best-effort traffic.  Additional plans include mapping between IP
 DiffServ markings [14,46] and IEEE 802 priorities.
 The statement was also made that QoS over the wireless link is not
 the fundamental problem, rather it is handling mobility aspects and
 seamless adaptation across handoffs without service disruption.
 There were concerns about mechanisms establishing per-flow state
 (RSVP [13]).  Issues include scaling of state, and signaling overhead
 and setup delays on roaming events.  DiffServ [9] approach allows
 allocating QoS for aggregate traffic class, which simplifies roaming.
 However, DiffServ requires measurement and allocation adjustment over
 time, and policing to limit amount of QoS traffic injected.

3.6.2 Discussion on Path QoS Discovery

 The HDR high speed wireless packet data system under development at
 Qualcomm highlights unique characteristics of some wireless media.
 This system provides users a channel rate between 38.4Kb/s and
 2.4Mb/s, with throughput dependent on channel loading and distance
 from network access point.  This gave rise to considerable discussion
 on whether it might be possible to discover and provide feedback to
 the application regarding current link or path QoS being received.
 This might enable some form of application adaptation.
 In the case of the HDR system it was indicated that no such feedback
 is currently available.  Additionally, it was argued that this is in
 accord with the current Internet stack model, which does not provide
 any mechanisms to expose this type of information.  Counter arguments
 stated that there are growing demands in Internet QoS working groups
 requesting exposure of this type of information via standardized
 APIs.  Members working on GPRS protocols also indicated frustration
 in deploying QoS capabilities without exposure of this information.
 This clearly seemed a topic for further investigations.
 A final area of discussion on QoS discovery focused on the question
 of how a server application might find out the capabilities of a
 receiver.  This could allow for application adaptation to client
 device and path characteristics.  One suggestion proposed use of RSVP
 payload, which is able to transport QoS information.  A second

Mitzel Informational [Page 19] RFC 3002 IAB Wireless Workshop December 2000

 alternative is to push capability exchange and negotiation to the
 application layer.  Discussion on this topic was brief, as
 application issues were deemed outside the workshop charter, however
 this also seems an area open for future investigation.

3.7 Discussion on Header Compression

 A critical deterrent to Internet protocol adoption in the highly
 band-width constrained wireless cellular environment is the bit
 overhead of the protocol encoding.  Examples presented highlighted
 how a voice application (layered over IP [52,19], UDP [51], and RTP
 [57]) requires a minimum of 40 bytes of headers for IPv4 or 60 bytes
 for IPv6 before any application payload (e.g., 24 byte voice sample).
 This overhead was also presented as a contributing factor for the
 creation of WAP Wireless Datagram Protocol (WDP) rather than IP for
 very low datarate bearers.
 Discussion on header compression techniques to alleviate these
 concerns focused on work being performed within the IETF Robust
 Header Compression (rohc) working group.  This working group has
 established goals for wireless environment, to conserve radio
 spectrum, to accommodate mobility, and to be robust to packet loss
 both before the point where compression is applied and between
 compressor and decompressor.  Additional requirements established
 were that the technique be transparent, does not introduce additional
 errors, and that it is compatible with common protocol layerings
 (e.g., IPv4, IPv6, RTP/UDP/IP, TCP/IP).
 The primary observation was that this problem is now largely solved!
 The working group is currently evaluating the ROCCO [38] and ACE [42]
 protocols, and expects to finalize its recommendations in the near
 future.  It was reported that these encodings have a minimum header
 of 1 byte and result in average overhead of less than 2 bytes for an
 RTP/UDP/IP packet.  There is some extra overhead required if
 transport checksum is required and some issues still to be analyzed
 related to interoperation with encryption and tunneling.
 A detriment to IPv6 adoption often cited is its additional header
 overhead, primarily attributed to its larger address size.  A
 secondary observation made was that it's believed that IPv6
 accommodates greater header compression than IPv4.  This was
 attributed to the elimination of the checksum and identification
 fields from the header.
 Discussion on use of WWW protocols over wireless highlighted protocol
 encodings as another potential detriment to their adoption.  A number
 of alternatives were mentioned for investigation, including use of a
 "deflate" Content-Encoding, using compression with TLS [20], or

Mitzel Informational [Page 20] RFC 3002 IAB Wireless Workshop December 2000

 Bellovin's TCP filters.  Observation was made that it could be
 beneficial to investigate more compact alternative encoding of the
 WWW protocols.

3.8 Discussion on Applications Protocols

 IETF protocol developments have traditionally taken the approach of
 preferring simple encode/decode and word alignment at the cost of
 some extra bit transmissions.  It was stated that optimizing protocol
 encoding for bit savings often leads to shortcomings or limitations
 on protocol evolution.  However, it was also argued that environments
 where physical limitations have an effect on transmission capacity
 and system performance may present exceptions where optimized
 encodings are beneficial.  Cellular wireless and near-space satellite
 may fall into this category.
 The WAP protocols exhibit several examples where existing Internet
 protocols were felt to be too inefficient for adoption with very low
 datarate bearer services and limited capability devices.  The WAP
 Wireless Session Protocol (WSP) is based on HTTPv1.1 [23], however
 WSP incorporates several changes to address perceived inefficiencies.
 WSP uses a more compact binary header encoding and optimizations for
 efficient connection and capability negotiation.  Similarly, the WAP
 Wireless Application Environment (WAE) uses tokenized WML and a tag-
 based browser environment for more efficient operation.
 Additional requests for more efficient and compact protocol
 encodings, and especially improved capability negotiation were raised
 during discussion on usage of WWW protocols with wireless handheld
 devices.
 Finally, work within the near-space satellite environment has pointed
 out other physical limitations that can affect performance.  In this
 case the long propagation delays can make "chatty" protocols highly
 inefficient and unbearable for interactive use.  This environment
 could benefit from protocols that support some form of "pipelining"
 operation.
 There seemed broad agreement that many of these observations
 represent valid reasons to pursue optimization of protocol
 operations.  Investigation of compact protocol encoding, capability
 negotiation, and minimizing or overlapping round trips to complete a
 transaction could all lead to improved application performance across
 a wide range of environments.

Mitzel Informational [Page 21] RFC 3002 IAB Wireless Workshop December 2000

3.9 Discussion on Proxy Agents

 Proxy agents are present in a number of the wireless and mobile
 architectures.  They're often required to gateway between
 communication domains; terminate tunnel and translate between
 telephony system and Internet protocols (GPRS), or to escape the
 "walled garden" (WAP).  In conjunction with limited capability
 handheld devices a proxy might be deployed to offload expensive
 processing such as public key operations, perform content filtering,
 or provide access to "backend" applications (e.g., email, calendar,
 database).  In other cases the proxy may be required to work around
 protocol deployment limitations (e.g., NAT with limited IPv4
 addresses).
 The discussion on proxy agents primarily recognized that there are a
 range of proxy agent types.  Proxies may operate by intercepting and
 interpreting protocol packets, or by hijacking or redirecting
 connections.  Some types of proxy break the Internet end-to-end
 communication and security models.  Other proxy architectures may
 limit system scalability due to state or performance constraints.
 There was some desire to conduct further study of proxy agent models
 to evaluate their effect on system operation.

3.10 Discussion on Adoption of IPv6

 Projections were presented claiming 1200 million cellular (voice)
 subscribers, 600 million wired stations on the Internet, and over 600
 million wireless data ("web handset") users by the year 2004.  Right
 up front there was caution about these projections, especially the
 wireless data since it is highly speculative with little history.
 Secondly, there was some doubt regarding potential for significant
 revenues from user base over 1 billion subscribers; this may be
 pushing the limits of world population with sufficient disposable
 income to afford these devices.  However, there was broad consensus
 that cellular and Internet services are going to continue rapid
 growth and that wireless data terminals have potential to form a
 significant component of the total Internet.  These conclusions
 seemed to form the basis for many additional recommendations to push
 for adoption of IPv6 protocols in emerging (3G) markets.
 In nearly all the presentations on 3G cellular network technologies
 discussion on scaling to support the projected large number of
 wireless data users resulted in strong advocacy by the Internet
 representatives for adoption of IPv6 protocols.  There were some
 positive signs that groups have begun investigation into IPv6.  For
 example, 3GPP has already defined IPv6 as an option in their 1998 and
 1999 specifications (release R98 and R99), and are considering

Mitzel Informational [Page 22] RFC 3002 IAB Wireless Workshop December 2000

 specifying IPv6 as mandatory in the release 2000.  The MWIF effort is
 also cognizant of IPv4 and IPv6 issues and is currently wrestling
 with their recommendations in this area.
 Although there was limited positive signs on IPv6 awareness,
 indication is that there are long fights ahead to gain consensus for
 IPv6 adoption in any of the 3G standards efforts.  There was
 considerable feedback that the telephony carriers perceive IPv6 as
 more difficult to deploy, results in higher infrastructure equipment
 expenses, and adds difficulty in interoperation and gatewaying to the
 current (IPv4) Internet.  Arguments for sticking with IPv4 primarily
 came down to the abundance and lower pricing of IPv4-based products,
 and secondary argument of risk aversion; there is currently minimal
 IPv6 deployment or operational experience and expertise, and the
 carriers do not want to drive development of this expertise.
 Finally, some groups argue IPv4 is sufficient for "walled garden"
 use, using IPv4 private address space (i.e., the "net 10" solution).
 One other area of concern regarding IPv6 usage is perceived memory
 and processing overhead and its effect on small, limited capability
 devices.  This was primarily directed at IPv6 requirement for IPsec
 implementation to claim conformance.  Arguments that continued
 increase in device capacity will obviate these concerns were
 rejected.  It was stated that power constraints on these low-end
 devices will continue to force concerns on memory and processing
 overhead, and impact introduction of other features.  There was no
 conclusion on whether IPsec could be made optional for these devices,
 or the effect if these devices were "non-compliant".
 Emerging 3G cellular networks appear ideal environment for IPv6
 introduction.  IPv6 addresses scaling requirements of wireless data
 user projections and eliminates continued cobbling of systems
 employing (IPv4) private address space and NAT.  This appears an area
 for IAB and Internet community to take a strong stance advocating
 adoption of IPv6 as the various 3G forums wrestle with their
 recommendations.

3.11 Discussion on Signaling

 Discussion on signaling focused on call setup and control functions,
 and the effects of mobility.  The 3G.IP group has investigated
 standardizing on either H.323 [32] or SIP [30].  Currently support
 seems to be split between the protocols, and neither seemed ideal
 without support for mobility.  During discussion on VoIP it was
 presented that SIP does support mobility, with graceful handling of
 mobile handoff, updating location information with remote peer, and
 even simultaneous handoff of both endpoints.  The problem with SIP
 adoption seems to be its slow standardization brought about by

Mitzel Informational [Page 23] RFC 3002 IAB Wireless Workshop December 2000

 focusing on the harder multicast model rather than expediting
 definition of a unicast "profile".  There seems great need for IETF
 to expedite finalization of SIP, however some argued at this point
 it's likely many products will need to develop support for both SIP
 and H.323, and for their interoperation.
 A short discussion was also raised on whether it is the correct model
 to incorporate the additional protocol mechanisms to accommodate
 mobility into the SIP signaling.  An alternative model might be to
 build on top of the existing mobile IP handoff facilities.  There was
 no conclusion reached, however it seemed an area for further
 investigation.

3.12 Discussion on Interactions Between IETF and Other Standards

   Organizations
 There were many examples where non-IETF standards organizations would
 like to directly adopt IETF standards to enable Internet (or similar)
 services.  For example IEEE 802.11 WLAN relies on adoption of IETF
 standards for mobile IP, end-to-end security, and AAA services.  3GPP
 is looking into the IETF work on header compression.  WAPF derived
 its transport, security, and application environment from Internet
 protocols.  At first glance these would seem successes for adoption
 of Internet technologies, however the decision to rely on IETF
 standards often introduced frustrations too.
 One common theme for frustration is differences in standardization
 procedures.  For instance, 3GPP follows a strict model of publishing
 recommendations yearly; any feature that cannot be finalized must be
 dropped.  On the other hand the IETF working groups have much less
 formalized schedules, and in fact often seem to ignore published
 milestone dates.  This has led to a common perception within other
 standards organizations that the IETF cannot deliver [on time].
 A second area identified where IETF differs from other organizations
 is in publication of "system profile".  For example defining
 interoperation of IPsec, QoS for VoIP and video conferencing, and
 billing as a "service".  Wading through all the protocol
 specifications, deciding on optional features and piecing together
 the components to deliver a commercial quality service takes
 considerable expertise.
 Thirdly, there was often confusion about how to get involved in IETF
 standards effort, submit requirements, and get delivery commitments.
 Many people seem unaware and surprised at how open and simple it is
 to join in IETF standardization via working group meetings and
 mailing list.

Mitzel Informational [Page 24] RFC 3002 IAB Wireless Workshop December 2000

 There wasn't really a large amount of discussions on ways to address
 these differences in standards practices.  However, it did seem
 beneficial to understand these concerns and frustrations.  It seemed
 clear there can be some benefits in improving communication with
 other standards organizations and encouraging their participation in
 IETF activities.

4 Recommendations

 The IAB wireless workshop provided a forum for those in the Internet
 research community and in the wireless and telephony community to
 meet, exchange information, and discuss current activities on using
 Internet technology in wireless environments.  However the primary
 goal from the perspective of the IAB was to reach some understanding
 on any problems, both technical or perceived deficiencies, deterring
 the adoption of Internet protocols in this arena.  This section
 documents recommendations of the workshop on actions by the IAB and
 IESG, IRTF research efforts, and protocol development actions for the
 IETF to address these current deficiencies and foster wider
 acceptance of Internet technologies.

4.1 Recommendations on Fostering Interaction with Non-Internet Standards

  Organizations
 A clear consensus of the workshop is that dialog needs to be
 improved.  The Internet community should attempt to foster
 communication with other standards bodies, including WAPF, MWIF,
 3GPP, 3G.IP, etc.  The goal is to "understand each others problems",
 provide for requirements input, and greater visibility into the
 standardization process.

4.1.1

 It was recommended to take a pragmatic approach rather than
 formalizing liaison agreements.  The formalized liaison model is
 counter to the established Internet standards process, is difficult
 to manage, and has met with very limited success in previous trials.
 Instead, any relevant IETF working group should be strongly
 encouraged to consider and recommend potential liaison requirements
 within their charter.

4.1.2

 It was recommended to avoid formation of jointly sponsored working
 groups and standards.  Once again this has shown limited success in
 the past.  The preferred mode of operation is to maintain separate
 standards organizations but to encourage attendance and participation
 of external experts within IETF proceedings and to avoid overlap.

Mitzel Informational [Page 25] RFC 3002 IAB Wireless Workshop December 2000

 An exception to this style of partitioning meeting sponsorship is
 less formal activities, such as BOFs.  It was recommended that
 sponsoring joint BOF could be beneficial.  These could enable
 assembly of experts from multiple domains early in the process of
 exploring new topics for future standards activities.

4.1.3

 A principle goal of fostering communication with other standards
 organizations is mutual education.  To help in achieving this goal
 recommendations were made related to documenting more of the history
 behind Internet standards and also in coordinating document reviews.
 It was recommended that IETF standards groups be encouraged to create
 or more formally document the reasons behind algorithm selection and
 design choices.  Currently much of the protocol design history is
 difficult to extract, in the form of working group mail archives or
 presentations.  Creation of these documents could form the basis to
 educate newcomers into the "history" and wisdom behind the protocols.
 It was recommended that mutual document reviews should be encouraged.
 This helps to disseminate information on current standards activities
 and provides an opportunity for external expert feedback.  A critical
 hurdle that could severely limit the effectiveness of this type of
 activity is the intellectual property and distribution restrictions
 some groups place on their standards and working documents.

4.2 Recommendations for Dealing with "Walled Garden" Model

 There are several perceived benefits to the "walled garden" (captive
 customer) model, similar to current deployment of "intranets".  These
 range from simplified user security to "captive customer" economic
 models.  There was disagreement on the extent this deployment model
 might be perpetuated in the future.  However it is important to
 recognize this model exists and to make a conscious decision on how
 to accommodate it and how it will affect protocol design.

4.2.1

 It was strongly recommended that independent of the ubiquity of the
 "walled garden" deployment scenario that protocols and architectural
 decisions should not target this model.  To continue the success of
 Internet protocols at operating across a highly diverse and
 heterogeneous environment the IETF must continue to foster the
 adoption of an "open model".  IETF protocol design must address
 seamless, secure, and scalable access.

Mitzel Informational [Page 26] RFC 3002 IAB Wireless Workshop December 2000

4.2.2

 Recognition that the "walled garden" model has some perceived
 benefits led to recommendations to better integrate it into the
 Internet architecture.  These focused on service location and escape
 from the "walled garden".
 It was recommended to investigate standard protocols for service and
 proxy discovery within the "walled garden" domain.  There are already
 a number of candidate mechanisms, including static preconfiguration,
 DNS [22,27,44,45], BOOTP [18], DHCP [21], SLP [28], and others.
 Specific recommendations on use of these protocols in this
 environment can help foster common discovery methods across a range
 of access devices and ease configuration complexity.
 It was recommended to investigate standard methods to transport
 through the garden wall (e.g., escape to the Internet).  It seemed
 clear that a better model is required than trying to map all access
 over a HTTP [23] transport connection gateway.  One suggestion was to
 propose use of IP!

4.3 Recommendations on IPv4 and IPv6 Scaling

 Wireless operators are projecting supporting on the order of 10's to
 100's million users on their Internet-based services.  Supporting
 this magnitude of users could have severe scaling implications on use
 of the dwindling IPv4 address space.

4.3.1

 There was clear consensus that any IPv4-based model relying on
 traditional stateless NAT technology [60] is to be strongly
 discouraged.  NAT has several inherent faults, including breaking the
 Internet peer-to-peer communication model, breaking end-to-end
 security, and stifling deployment of new services [16,29,31].  In
 addition, the state and performance implications of supporting 10's
 to 100's million users is cost and technologically prohibitive.

4.3.2

 Realm specific IP (RSIP) [10,11] has potential to restore the end-
 to-end communication model in the IPv4 Internet, broken by
 traditional NAT.  However there was considerable reluctance to
 formally recommend this as the long term solution.  Detriments to its
 adoption include that the protocol is still being researched and
 defined, and potential interactions with applications, QoS features,
 and security remain.  In addition, added signaling, state, and
 tunneling has cost and may be technologically prohibitive scaling.

Mitzel Informational [Page 27] RFC 3002 IAB Wireless Workshop December 2000

4.3.3

 The clear consensus of the workshop was to recommend adoption of an
 IPv6-based solution to support these services requiring large
 scaling.  Adoption of IPv6 will aid in restoring the Internet end-
 to-end communication model and eliminates some roaming issues.
 Adoption of IPv6 in this marketspace could also help spur development
 of IPv6 products and applications, and hasten transition of the
 Internet.  It was recognized that some application gateways are
 required during transition of the IPv4 Internet, however it was felt
 that the scaling and roaming benefits outweighed these issues.

4.3.4

 It was recommended that an effort be made to eliminate any
 requirement for NAT in an IPv6 Internet.  The IAB believes that the
 IPv6 address space is large enough to preclude any requirement for
 private address allocation [55] or address translation due to address
 space shortage [15].  Therefore, accomplishing this should primarily
 require installing and enforcing proper address allocation policy on
 registry and service providers.  It was recommended to establish
 policies requiring service providers to allocate a sufficient
 quantity of global addresses for a sites use.  The feeling was that
 NAT should be easily eliminated provided efficient strategies are
 defined to address renumbering [17,62] and mobility [37] issues.

4.4 Recommendations on IPv4 and IPv6 Mobility

 An inherent characteristic of wireless systems is their potential for
 accommodating device roaming and mobility.  Scalable and efficient
 support of this mobility within Internet protocols can aid in pushing
 native IP services out to the mobile devices.

4.4.1

 Several limitations were identified relating to current specification
 of mobile IPv4 [48].  Primary among these limitations is that
 mechanisms to support redundant home agents and failover are not
 currently defined.  Redundant home agents are required to avoid
 single point of failure, which would require (proprietary)
 extensions.  Additional deficiencies related to lack of route
 optimization, and tunneling and path MTU issues were also identified.
 Due to these limitations there was reluctance to recommend this as a
 solution.

Mitzel Informational [Page 28] RFC 3002 IAB Wireless Workshop December 2000

4.4.2

 It was recommended to encourage adoption of IPv6 mobility extensions
 [37] to support roaming capabilities in the wireless environment.  IP
 mobility over IPv6 incorporates improvements to address several
 limitations of the IPv4-based mobility.  The ability to use
 autoconfiguration for "care of" address improves robustness and
 efficiency.  Additionally, path MTU is more easily adapted when a
 router forwards to a new "care of" address.
 Building wireless roaming atop IPv6-based mobility may introduce
 IPv4/IPv6 transition issues unique to the mobile environment.  It was
 recommended to add investigation of these issues to the charter of
 the existing IETF Next Generation Transition (ngtrans) working group,
 provided any mobile IP interoperation issues be identified.

4.4.3

 Scalable and widespread authentication, authorization, and accounting
 (AAA) services are critical to the deployment of commercial services
 based on (wireless) mobile IP.  Some work is progressing on
 definition of these standards for IP mobility [26,49].  However, due
 to the pivotal role of these protocols on the ability to deploy
 commercial services, it was recommended to make finalization of these
 AAA standards and investigation of AAA scalability as high
 priorities.

4.5 Recommendations on TCP and Transport Protocols

 The wireless environment and applications place additional
 requirements on transport protocol.  Unique link error and
 performance characteristics, and application sensitivity to
 connection setup and transaction semantics has led to "optimized"
 transports specific to each environment.  These new transports often
 lack robustness found in Internet  transport and place barriers to
 seamless gatewaying to the Internet.  It was felt that better
 education on transport design and cooperation on Internet transport
 evolution could lead to significant improvements.

4.5.1

 It was recommended that the IETF Transport Area (tsv) working group
 document why Internet transport protocols are the way they are.  The
 focus should be on generic transport issues and mechanisms, rather
 than TCP specifics.  This should capture usage and tradeoffs in
 design of specific transport mechanisms (e.g., connection

Mitzel Informational [Page 29] RFC 3002 IAB Wireless Workshop December 2000

 establishment, congestion control, loss recovery strategies, etc.),
 and document some of the history behind transport research in the
 Internet.
 This "entry point" document into transport design is in direct
 support of the recommendations in section 4.1 to foster communication
 and mutual education.  In addition it was deemed critical that the
 Internet community make it very clear that congestion control is not
 optional.  Internet researchers have learned that optimizing for a
 single link or homogeneous environment does not scale.  Early work by
 Jacobson [34,35], standardization of TCP congestion control [5], and
 continuing work within the IETF Endpoint Congestion Management (ecm)
 working group could provide excellent basis for education of wireless
 transport designers.

4.5.2

 It was recommended that the IETF actively solicit input from external
 standards bodies on identifying explicit requirements and in
 assessing inefficiencies in existing transports in support of
 cellular and wireless environments.  This has proven highly effective
 in identifying research topics and in guiding protocol evolution to
 address new operational environments, for instance in cooperation
 with groups doing satellite-based internetworking [4,6].

4.5.3

 It was recommended that the IAB make wireless standards bodies aware
 of the existence, and get them active in, the IETF Transport Area
 (tsv) working group.  This transport "catch all" could provide an
 excellent forum for workers outside the Internet community to propose
 ideas and requirements, and engage in dialog with IESG members prior
 to contributing any formal proposal into the IETF or incurring
 overhead of working group formation.

4.5.4

 Mobile radio environments may often be subject to frequent temporary
 outages.  For example, roaming through an area that is out of range
 of any base station, or disruptions due to base station handoffs.
 This violation of the congestive loss assumption of TCP can have
 severe detrimental effect on transport performance.  It was
 recommended to investigate mechanisms for improving transport
 performance when these non-congestive loss can be detected.  Areas
 for potential research identified include incorporation of "hints" to
 the sender providing Non-Congestive Loss Indication (NCLI) or
 stimulating transmission after link recovery via Source Encourage

Mitzel Informational [Page 30] RFC 3002 IAB Wireless Workshop December 2000

 (SE) message [39].  This likely falls to the auspice of the IETF
 Performance Implications of Link Characteristics (pilc) working
 group.

4.5.5

 Many wireless applications require transaction semantics and are
 highly sensitive to connection establishment delays (e.g., WAP).
 However, it is still desirable to efficiently support streaming of
 large bulk transfers too.  It was recommended to investigate
 tradeoffs in supporting these transaction and streaming connections.
 Potential areas for investigation include tradeoffs between minimal
 transaction transport and potential security and denial of service
 (DoS) attacks, mechanisms to piggyback data during connection
 establishment to eliminate round trip delays, or ways for endpoints
 to cooperate in eliminating setup handshake for simple transactions
 while providing switch-over to reliable streaming for bulk transfers.

4.5.6

 It was recommended to look at (TCP) transport improvements specific
 to the wireless and mobile environment.  An example is to investigate
 reattachable transport endpoints.  This could allow for graceful
 recovery of a transport connection after a roaming or mobility event
 results in changes to one or both endpoint identifiers.  Another area
 for potential investigation is to develop targeted uses of D-SACK
 [25].  D-SACK provides additional robustness to reordered packets,
 which may prove beneficial in wireless environment where packets are
 occasionally corrupted.  Higher performance may be attainable by
 eliminating requirements on link-level retransmission maintaining
 in-order delivery within a flow.

4.6 Recommendations on Routing

 Unique routing requirements may be introduced in support of wireless
 systems, especially when viewing the mobile component as an
 autonomous system (AS).

4.6.1

 It was recommended that the IETF Routing Area commence investigation
 of extensions to the BGP protocol [54] to support additional policy
 features available within the ISO IDRP protocol [33].  The range of
 policy control desired includes adopting different identity or
 policies based on current point of attachment, and providing
 flexibility in path selection based on local policy and/or current

Mitzel Informational [Page 31] RFC 3002 IAB Wireless Workshop December 2000

 peer policy.  These features could be used for instance in support of
 requirements established in the Aeronautical Telecommunication
 Network (ATN).

4.6.2

 It was recommended that the IETF Routing Area commence investigation
 of extensions to the BGP protocol [54] to support additional QoS/TOS
 path selection features available within the ISO IDRP protocol [33].
 The range of policies include differentiating service level or path
 selection based on traffic classes.  An example, based on
 Aeronautical Telecommunication Network (ATN) requirements, might be
 differentiating path selection and service between airline control
 and passenger entertainment traffic.

4.7 Recommendations on Mobile Host QoS Support

 Wireless link bandwidth is often scarce (e.g., cellular) and/or
 shared (e.g., IEEE 802.11 WLAN).  Meeting application QoS needs
 requires accommodating these link characteristic, in addition to the
 roaming nature of mobile host.  Specialized support may be required
 from the network layer to meet both link and end-to-end performance
 constraints.

4.7.1

 It was recommended that the IETF Transport Area undertake
 investigation into providing QoS in the last leg of mobile systems.
 That is, between the mobile device and the network access point.
 This type of QoS support might be appropriate where the wireless link
 is the most constrained resource.  A potential solution to
 investigate is to employ an explicit reservation mechanism between
 the mobile host and the access point (e.g., RSVP [13]), while relying
 on resource provisioning or more scalable DiffServ [9] technologies
 within the core.

4.7.2

 It was recommended that the IETF Transport Area undertake
 investigation into end-to-end QoS when the path includes a mixture of
 wireless and wired technologies.  This investigation could focus on
 mechanism to communicate QoS characteristics in cellular network to
 the core network to establish end-to-end QoS guarantees.  An
 alternative investigation is to look into discovery problem of
 assessing current end-to-end performance characteristics, enabling
 for dynamic adaptation by mobile host.

Mitzel Informational [Page 32] RFC 3002 IAB Wireless Workshop December 2000

4.8 Recommendations on Application Mobility

 In a mobile environment with roaming, and mobile host disconnect and
 reconnect at different attachment point it may be desirable to
 recover an incomplete application session.  It was recommended that
 the IRTF investigate application mobility at this level.  The goal is
 to achieve a smooth recovery after a disconnect period; something
 more graceful than a "redial".  Currently there does not appear to be
 sufficient information available within the network stack, this may
 require instantiation of some form of "session" layer.

4.9 Recommendations on TCP/IP Performance Characterization in WAP-like

  Environment
 WAPF has gone to considerable effort to develop unique transport
 protocol and optimizations due to perception that TCP/IP protocol
 stack is too expensive.  Much of this was predicated on WAP
 requirements to support very low datarate bearer services.  It was
 recommended that members of the IRTF evaluate TCP/IP stack
 performance in WAP-like environment to quantify its behavior and
 applicability.  The focus should include investigation of code and
 memory space requirements, as well as link usage to complete a single
 transaction for current WAP protocols and for both IPv4 and IPv6.
 This work should result in better characterization of TCP/IP
 performance in highly constrained devices and network,
 recommendations to the IETF on protocol enhancements to optimize
 performance in this environment, and recommendations to WAPF on
 suitability of deploying native IP protocols.

4.10 Recommendations on Protocol Encoding

 IETF protocol developments have traditionally taken the approach of
 preferring simple encode/decode and word alignment at the cost of
 some extra bit transmissions.  This overhead may prove too burdensome
 in some bandwidth constrained environments, such as cellular wireless
 and WAP.  Work within the IETF Robust Header Compression (rohc)
 working group may go a long way to reducing some of these detriments
 to Internet protocols deployment.  However, there may be potential
 for additional savings from investigation of alternative encoding of
 common Internet protocols.  It was recommended that members of the
 IRTF evaluate general techniques that can be used to reduce protocol
 "verbiage".  Examples might include payload compression techniques or
 tokenized protocol encoding.

Mitzel Informational [Page 33] RFC 3002 IAB Wireless Workshop December 2000

4.11 Recommendations on Inter-Domain AAA Services

 Commercial roaming and mobility services are likely to require
 exchange of authentication, authorization, and billing services
 spanning multiple domains (service providers).  This introduces
 requirements related to establishing a web or hierarchy of trust
 across multiple autonomous domains.  Standard protocols to specify
 and exchange usage policies and billing information must also be
 established.  Some work is progressing on scoping out the issues and
 a framework [7,64].  However, there are significant issues to be
 solved to enable a scalable, Internet-wide solution.  Due to the
 pivotal role of these protocols on the ability to deploy commercial
 services, it was recommended to make finalization of scalable inter-
 domain AAA as high priority within the IETF.

4.12 Recommendations on Bluetooth

 Bluetooth protocols and devices were originally optimized for a
 narrow application space.  However, there is interest in exploring
 the breadth to which protocol and device access can be extended.  One
 particular area of interest is exploring integration into, or
 gatewaying access to, the Internet.  It was recommended that the IETF
 pursue formation of a joint BOF to assemble experts from the IETF and
 Bluetooth communities to begin exploration of this problem.  This is
 in direct support of the recommendations in section 4.1 to foster
 communication and mutual education.

4.13 Recommendations on Proxy Architecture

 Proxy agents are often deployed to intercept and evaluate protocol
 requests (e.g., web cache, HTTP redirector, filtering firewall) or to
 gateway access between communication domains (e.g., traversing
 bastion host between private network and Internet or gatewaying
 between a cellular service and the Internet).  There are a number of
 potential architectures when contemplating development and deployment
 of one of these proxy agent.  It was recommended that members of the
 IRTF investigate taxonomy of proxy architectures and evaluate their
 characteristics and applicability.  Each type of proxy should be
 characterized, for example, by its effect on Internet end-to-end
 model, and security, scaling, and performance implications.  The
 results of this study can help educate developers and network
 operators on the range of proxy available and recommend solutions
 that are least disruptive to Internet protocols.

Mitzel Informational [Page 34] RFC 3002 IAB Wireless Workshop December 2000

4.14 Recommendations on Justifying IPv6-based Solutions for Mobile /

   Wireless Internet
 IPv6 was strongly recommended to address scaling (see section 4.3)
 and mobility (see section 4.4) issues in the future Internet
 dominated by large numbers of wireless and mobile devices.  It was
 recommended that the IAB draft a formalized justification for these
 recommendations for adoption of IPv6-based solution.  It was believed
 that the "The Case for IPv6" [40] document should form an excellent
 basis for this justification.  In addition, documents highlighting
 architectural and operational pitfalls of continued reliance on IPv4
 and NAT also provide excellent justification [29,31,59].  It was
 deemed urgent to submit these informational documents as inputs to
 other standards bodies (MWIF, 3GPP, 3G.IP), as many decisions are
 being made on Internet protocol adoption and this data could be
 highly influential.

5 Security Considerations

 This workshop did not focus on security.  However, mobility and
 wireless environment introduces additional complexities for security
 and potential attacks to user authentication and privacy.  The
 presentations by Asokan and by Calhoun referenced in section 2
 focused on security mechanisms in currently deployed cellular
 networks and evolution toward 3G cellular and IP networks.
 Discussion on the "walled garden" service model (see section 3.1)
 briefly mentions effects on simplifying security requirements.
 Section 3.3 raises a number of security issues related to wireless
 devices and mobility.  These include alternatives for establishing
 user identity and capabilities, securing network infrastructure from
 attacks, and security associations required for mobile IP and AAA
 operation.  Section 3.7 mentions interoperation issues between
 compression and encryption or tunneling, and finally section 3.9
 highlight potential for proxy agent to be used to offload expensive
 crypto operations.

6 Acknowledgments

 The author would like to thank all of the workshop participants for
 their feedback, encouragement, and patience during the writeup of
 this document.  I would especially like to thank Brian Carpenter for
 prompt responses to questions on the document organization and
 content.  Similarly, Charlie Perkins provided extensive feedback that
 dramatically improved and corrected statements throughout the report.
 Finally, Mikael Degermark, Sally Floyd, Heikki Hammainen, Geoff
 Huston, and Gabriel Montenegro contributed comments and responses to
 questions.

Mitzel Informational [Page 35] RFC 3002 IAB Wireless Workshop December 2000

7 Bibliography

 [1]  ACIRI.  TCP-Friendly Rate Control.  http://www.aciri.org/tfrc.
 [2]  A. Aggarwal, S. Savage, and T. Anderson.  Understanding the
      Performance of TCP Pacing.  Proceedings of IEEE Infocom 2000,
      March 2000.
 [3]  Allman, M., Floyd, S. and C. Partridge, "Increasing TCP's
      Initial Window", RFC 2414, September 1998.
 [4]  Allman, M., Glover, D. and L. Sanchez, "Enhancing TCP Over
      Satellite Channels using Standard Mechanisms",  RFC 2488,
      January 1999.
 [5]  Allman, M., Paxson, V. and W. Stevens, "TCP Congestion Control",
      RFC 2581, April 1999.
 [6]  Allman, M., Dawkins, S., Glover, D., Griner, J., Tran, D.,
      Henderson, T., Heidemann, J., Touch, J., Kruse, H., Ostermann,
      S., Scott, K. and J. Semke, "Ongoing TCP Research Related to
      Satellites", RFC 2760, February 2000.
 [7]  Arkko, J., "Requirements for Internet-Scale Accounting
      Management", Work in Progress.
 [8]  Bates, T., Chandra, R., Katz, D. and Y. Rekhter, "Multiprotocol
      Extensions for BGP-4", RFC 2283, February 1998.
 [9]  Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z. and W.
      Weiss, "An Architecture for Differentiated Services" RFC 2475,
      December 1998.
 [10] Borella, M., et al., "Realm Specific IP: Framework", Work in
      Progress.
 [11] Borella, M., et al., "Realm Specific IP: Protocol
      Specification", Work in Progress.
 [12] Braden, R., "T/TCP -- TCP Extensions for Transactions Functional
      Specification", RFC 1644, July 1994.
 [13] Braden, R., Zhang, L., Berson, S., Herzog, S. and S. Jamin,
      "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional
      Specification", RFC 2205, September 1997.
 [14] Brim, S., Carpenter, B. and F. Le Faucheur, "Per Hop Behavior
      Identification Codes", RFC 2836, May 2000.

Mitzel Informational [Page 36] RFC 3002 IAB Wireless Workshop December 2000

 [15] Carpenter, B., Crowcroft, J. and Y. Rekhter, "IPv4 Address
      Behaviour Today", RFC 2101, February 1997.
 [16] Carpenter, B., "Internet Transparency", RFC 2775, February 2000.
 [17] Crawford, M., "Router Renumbering for IPv6", RFC 2894, August
      2000.
 [18] Croft, B. and J. Gilmore, "Bootstrap Protocol (BOOTP)", RFC 951,
      September 1985.
 [19] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6)
      Specification", RFC 2460, December 1998.
 [20] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", RFC
      2246, January 1999.
 [21] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
      March 1997.
 [22] Everhart, C., Mamakos, L., Ullman, R. and P. Mockapetris, "New
      DNS RR Definitions", RFC 1183, October 1990.
 [23] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L.,
      Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol --
      HTTP/1.1", RFC 2616, June 1999.
 [24] Floyd, S. and T. Henderson, "The NewReno Modification to TCP's
      Fast Recovery Algorithm", RFC 2582, April 1999.
 [25] Floyd, S., Mahdavi, J., Mathis, M. and M. Podolsky, "An
      Extension to the Selective Acknowledgment (SACK) Option for
      TCP", RFC 2883, July 2000.
 [26] Glass, S., Hiller, T., Jacobs, S. and C. Perkins, "Mobile IP
      Authentication, Authorization, and Accounting Requirements", RFC
      2977, October 2000.
 [27] Gulbrandsen, A. and P. Vixie, "A DNS RR for specifying the
      location of services (DNS SRV)", RFC 2052, October 1996.
 [28] Guttman, E., Perkins, C., Veizades, J. and M. Day, "Service
      Location Protocol, Version 2", RFC 2608, June 1999.
 [29] Hain, T., "Architectural Implications of NAT", RFC 2993,
      November 2000.

Mitzel Informational [Page 37] RFC 3002 IAB Wireless Workshop December 2000

 [30] Handley, M., Schulzrinne, H., Schooler, E., and J. Rosenberg,
      "SIP: Session Initiation Protocol", RFC 2543, March 1999.
 [31] Holdrege, M. and P. Srisuresh, "Protocol Complications with the
      IP Network Address Translator (NAT)", Work in Progress.
 [32] International Telecommunication Union.  Visual Telephone Systems
      and Equipment for Local Area Networks which provide a Non-
      guaranteed Quality of Service.  Recommendation H.323, May 1996.
 [33] ISO/IEC.  Protocol for Exchange of Inter-Domain Routeing
      Information among Intermediate Systems to support Forwarding of
      ISO 8473 PDUs.  ISO/IEC IS10747, 1993.
 [34] V. Jacobson.  Congestion Avoidance and Control.  Computer
      Communication Review, vol. 18, no. 4 August 1988.
      ftp://ftp.ee.lbl.gov/papers/congavoid.ps.Z.
 [35] V. Jacobson.  Modified TCP Congestion Avoidance Algorithm.
      end2end-interest mailing list, April 30, 1990.
      ftp://ftp.isi.edu/end2end/end2end-interest-1990.mail.
 [36] Jacobson, V., Braden, R. and D. Borman, "TCP Extensions for High
      Performance", RFC 1323, May 1992.
 [37] Johnson, D. and C. Perkins, "Mobility Support in IPv6", Work in
      Progress.
 [38] Jonsson, L., et al., "RObust Checksum-based header COmpression
      (ROCCO)", Work in Progress.
 [39] Karn, P., et al., "Advice for Internet Subnetwork Designers",
      Work in Progress.
 [40] King, S., et al., "The Case for IPv6", Work in Progress.
 [41] J. Kulik, R. Coulter, D. Rockwell, and C. Partridge.  Paced TCP
      for High Delay-Bandwidth Networks.  Proceedings of IEEE Globecom
      '99, December 1999.
 [42] Le, K., et al., "Adaptive Header ComprEssion (ACE) for Real-Time
      Multimedia", Work in Progress.
 [43] Mathis, M., Mahdavi, J., Floyd, S. and A. Romanow, "TCP
      Selective Acknowledgment Options", RFC 2018, October 1996.

Mitzel Informational [Page 38] RFC 3002 IAB Wireless Workshop December 2000

 [44] Mockapetris, P., "Domain Names -- Concepts and Facilities", STD
      13, RFC 1034, November 1987.
 [45] Mockapetris, P., "Domain Names -- Implementation and
      Specification", STD 13, RFC 1035, November 1987.
 [46] Nichols, K., Blake, S., Baker, F. and D. Black, "Definition of
      the Differentiated Services Field (DS Field) in the IPv4 and
      IPv6 Headers", RFC 2474, December 1998.
 [47] Partridge, C., Mendez, T. and W. Milliken, "Host Anycasting
      Service", RFC 1546, November 1993.
 [48] Perkins, C., "IP Mobility Support", RFC 2002, October 1996.
 [49] Perkins, C. and P. Calhoun, "AAA Registration Keys for Mobile
      IP", Work in Progress.
 [50] Perkins, C. and D. Johnson, "Route Optimization in Mobile IP",
      Work in Progress.
 [51] Postel, J., "User Datagram Protocol", STD 6, RFC 768, August
      1980.
 [52] Postel, J., "Internet Protocol", STD 5, RFC 791, September 1981.
 [53] Ramakrishnan, K. and S. Floyd, "A Proposal to add Explicit
      Congestion Notification (ECN) to IP", RFC 2481, January 1999.
 [54] Rekhter, Y. and T. Li, "A Border Gateway Protocol 4 (BGP-4)",
      RFC 1771, March 1995.
 [55] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G. and E.
      Lear, "Address Allocation for Private Internets", BCP 5, RFC
      1918, February 1996.
 [56] Rigney, C., Rubens, A., Simpson, W. and S. Willens, "Remote
      Authentication Dial In User Service (RADIUS)", RFC 2138, April
      1997.
 [57] Schulzrinne, H., Casner, S., Fredrick, R. and V. Jacobson, "RTP:
      A Transport Protocol for Real-Time Applications", RFC 1889,
      January 1996.
 [58] J. Semke, J. Mahdavi, and M. Mathis.  Automatic TCP Buffer
      Tuning.  Proceedings of ACM SIGCOMM '98, September 1998.

Mitzel Informational [Page 39] RFC 3002 IAB Wireless Workshop December 2000

 [59] Srisuresh, P. and M. Holdrege, "IP Network Address Translator
      (NAT) Terminology and Considerations", RFC 2663, August 1999.
 [60] Srisuresh, P. and K. Egevang, "Traditional IP Network Address
      Translator (Traditional NAT)", Work in Progress.
 [61] Stewart, R., Xie, Q., Morneault, K., Sharp, C., Schwarzbauer,
      H., Taylor, T., Rytina, I., Kalla, M., Zhang, L. and V. Paxson,
      "Stream Control Transmission Protocol", RFC 2960, October 2000.
 [62] Thomson, S. and T. Narten, "IPv6 Stateless Address
      Autoconfiguration", RFC 2462, December 1998.
 [63] Touch, J., "TCP Control Block Interdependence", RFC 2140, April
      1997.
 [64] Vollbrecht, J., et al., "AAA Authorization Framework", Work in
      Progress.

Mitzel Informational [Page 40] RFC 3002 IAB Wireless Workshop December 2000

A Participants

   Juha Ala-Laurila                JUHA.ALA-LAURILA@nokia.com
   Mark Allman                     mallman@grc.nasa.gov
   Alastair Angwin                 angwin@uk.ibm.com
   N. Asokan                       n.asokan@nokia.com
   Victor Bahl                     bahl@microsoft.com
   Fred Baker                      fred@cisco.com
   Pravin Bhagwat                  pravinb@us.ibm.com
   Scott Bradner                   sob@harvard.edu
   Randy Bush                      randy@psg.com
   Pat Calhoun                     Pcalhoun@eng.sun.com
   Brian Carpenter                 brian@icair.org
   Mikael Degermark                micke@cs.arizona.edu
   Sally Floyd                     floyd@aciri.org
   Heikki Hammainen                HEIKKI.HAMMAINEN@NOKIA.COM
   Mark Handley                    mjh@aciri.org
   Bob Hinden                      hinden@iprg.nokia.com
   Christian Huitema               huitema@microsoft.com
   Chih-Lin I                      ci@att.com
   Van Jacobson                    van@packetdesign.com
   Phil Karn                       Karn@qualcomm.com
   John Klensin                    Klensin@JCK.com
   Jerry Lahti                     jerry.lahti@nokia.com
   Allison Mankin                  mankin@isi.edu
   Danny J. Mitzel                 mitzel@iprg.nokia.com
   Gabriel Montenegro              gab@sun.com
   Keith Moore                     moore@cs.utk.edu
   Eric Nordmark                   nordmark@sun.com
   Charles E. Perkins              charliep@iprg.nokia.com
   Jonne Soininen                  jonna.Soininen@nokia.com
   Chris A. Wargo                  cwargo@cnsw.com
   Lars Westberg                   Lars.Westberg@era.ericsson.se
   Lixia Zhang                     lixia@cs.ucla.edu

B Author's Address

 Danny J. Mitzel
 Nokia
 313 Fairchild Drive
 Mountain View, CA 94043
 USA
 Phone: +1 650 625 2037
 EMail: mitzel@iprg.nokia.com

Mitzel Informational [Page 41] RFC 3002 IAB Wireless Workshop December 2000

Full Copyright Statement

 Copyright (C) The Internet Society (2000).  All Rights Reserved.
 This document and translations of it may be copied and furnished to
 others, and derivative works that comment on or otherwise explain it
 or assist in its implementation may be prepared, copied, published
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 kind, provided that the above copyright notice and this paragraph are
 included on all such copies and derivative works.  However, this
 document itself may not be modified in any way, such as by removing
 the copyright notice or references to the Internet Society or other
 Internet organizations, except as needed for the purpose of
 developing Internet standards in which case the procedures for
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 followed, or as required to translate it into languages other than
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 The limited permissions granted above are perpetual and will not be
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 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
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 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

 Funding for the RFC Editor function is currently provided by the
 Internet Society.

Mitzel Informational [Page 42]

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