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rfc:ien:ien121
                                                             J. Postel

IEN 121 ISI

                                                       25 October 1979
      Internet Meeting Notes - 10, 11, 12 & 13 September 1979

I. INTRODUCTION TO UCL - Jones

 Ron welcomed us to UCL and discussed the arrangements for facilities,
 refreshments, and lunch.

II. OVERVIEW AND OBJECTIVES - Cerf

 Vint reviewed the need for a working internet system and cited the
 performance of the system as a key issue.  The development of
 procedures to measure and test the performance of the internet are
 now important.  Vint has pointed out that several conceptual design
 issues need to be resolved, for example, protocol support for voice
 conferencing in the internet.

III. STATUS REPORTS

 A.  DARPA - Cerf
    Vint reported that the Director of the ARPA Information Processing
    Techniques Office, Col. Dave Russell retired on 31 August.  The
    new Director is Dr. Robert Kahn.
    The standardization of IP and TCP for use as the DOD networks
    protocol is progressing.  Dr. Robert Lyons at DCEC is the
    Executive Agent.  The only changes that are necessary are to
    incorporate mechanisms to pass the security and precedence
    information between the application program and TCP, and between
    TCP and IP.  There already is an IP option to carry that
    information in the internet.
    There is a need for a way to test TCP implementations and
    applications that use TCP without taking a service machine down.
    For TOPS20s this will be satisfied by using BBNF.  BBNF is
    currently only on the BBN RCCNET but will be connected to the
    ARPANET for October through December 1979.
    Vint acknowledged that there have been hardware delivery delays
    that have had a substantial impact on the internet program.  The
    delivery schedules from manufactures are very long.

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    The program managers in the ARPA office are coordinating to have
    all new applications use internet protocols.
 B.  BBN - Haverty, Plummer, Strazisar, McNeill, Flood Page
    Jack reported that the BBN-Unix TCP is in regular use.  Currently
    work is in progress to provide a user interface to the IP layer.
    The IP support is available as a subroutine package.  The
    interface will be similar to the TOPS20 interface documented in
    IEN 108.  BBN is also working on a VAX UNIX with the goal of
    having the current 11/70 UNIX and VAX UNIX be compatible at the
    applications level.
    Bill reported on the plan to attach BBNF to the ARPANET for ease
    in testing TCP and TCP using applications.  In doing this testing
    it is preferred to have one person at a time to simplify the
    identification of problems.  Note that one will have to use new
    1822 (96-bit leaders) to access BBNF since it will be on IMP 67.
    The latest IP and TCP and Telnet are installed at ISID and ISIE
    TOPS20 Systems.  In the last month or two several bugs have been
    identified and fixed.  The next major step is to complete the
    TENEX version of TCP-4 and to eliminate any remaining instances of
    TCP-2.5.  It is assumed that both the Packet Radio Project and UCL
    have completed their conversion to version 4, and that as soon as
    the SATNET project completes its conversion version 2.5 can be
    eliminated. The LDRSRV program was converted to use IP in a few
    hours.  An FTP on TCP, based on ARPA FTP, is in debugging.
    Ginny reported that several gateways are running, most are MOS
    based.  It is planned to phase out the remaining ELF based
    gateways.
       MOS Gateways
          at UCL between UCLNET and SATNET
          at NDRE between ARPANET and SATNET
          at BBN between ARPANET and SATNET
          at SRI between PRNET and ARPANET
       ELF Gateways
          at Ft. Bragg between PRNET and ARPANET
    It is planned to install a gateway at COMSAT between SATNET and
    the COMSAT local net.  There is a new monitoring system.  A
    configuration with a port expander and a gateway in the same
    machine is planned, it will be a tight fit.
    Dale reported on the SATNET conversion to use IP.  There are still

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    a number of programs to be converted, but it could be completed in
    about a month.  Most of the remaining programs are used for
    maintenance or error recover.  A weekend test was conducted using
    IP only.  The major event impacting SATNET will be the removal of
    the NORWAY-LONDON ARPANET line at the end of September.  This
    means all the LONDON ARPANET traffic will be routed via SATNET.
    David noted that the scheduled GMCC demonstration will be a
    presentation, since there is nothing to demonstrate.
 C.  COMSAT - Mills
    Dave reported that the ETAM and GOONHILLY PSPs are in the field
    and the TANUM PSP will be shipped soon.  There have been some
    minor problems, for example, the software checksum and the
    hardware checksum do not agree.  It is expected that the PSPs will
    be on the air next month.
    Much of the COMSAT activity during the last few months has been
    directed to the NTC Demo in November and development of the Demo
    Terminal software. Currently, we have made arrangements for a
    suitable room and are now planning installation of lines,
    terminals and other gear. The demo will include speech, fax and
    the usual interactive and bulk transfers between ARPANET hosts and
    the Demo Terminal.
    The Demo Terminal software has been checked out at UCL using an
    LSI-11, floppy disk, LPCM and Port Expander connected to UCLNET
    (net 13). TCP/Telnet was tested with ISIE via UCLNET, SATNET and
    ARPANET. FTP was checked out in loopback mode via the UCL Gateway.
    The LPCM was operated in expensive dictaphone mode only, since
    support is not yet complete for SATNET streams. This software will
    play with the Demo Terminal software at COMSAT and at the NTC
    Demo.
    At COMSAT a Dacom 450 FAX machine has been delivered. This will be
    connected to the Demo Terminal and taken to the NTC site. Software
    to support this machine is now in frenzied development. When
    complete an update will be distributed to UCL. For local testing
    we are trying to arrange a direct connection to ARPANET (avoiding
    the SATNET for the time being) for debugging.
 D.  DCA - Cain
    Ed reported that DCEC has a small (2-page) "C" program running in
    an 11/34 with two 1822 interfaces which implements a gateway.

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 E.  DOD - McFarland
    Ray noted that mid October is the target date for the draft DOD
    Standards IP/TCP document.  These documents will be rewritten to
    military document conventions.
 F.  ISI STATUS - Postel
    Jon noted that ISI is not implementing any IP, TCP or Gateways.
    ISI did attempt to write a program that used TCP on TOPS20.  This
    program did not work (TOPs'20 crashed).  Debugging is in progress
    with Bill Plummer and the ISI systems staff.  ISI is working on an
    Internet Message Program.  This is in an early testing phase and
    will be using TCP for inter module communication.
 G.  LL - Forgie
    Jim noted that the main Lincoln effort has been on the ST protocol
    to be discussed later and described in IEN 119.
    Experiments with ARPANET-SATNET speech have been conducted with
    one source/destination in the ARPANET and another in the SATNET.
    There have been unexpectedly large delays in the SATNET streams,
    and in matching the ARPANET to the SATNET in the special purpose
    Gateway.
 H.  MIT - Clark, Chiappa
    Dave discussed the status of the LSCNET.  There is a 5 node system
    up and running.  The development of a version 2 interface is in
    progress.  There has been difficulty getting an LSCNET/ARPANET
    gateway working due to low level hardware problems.  A Trivial
    File Transfer has been implemented directly on IP.  In Multics the
    IP layer will act as a gateway.  MIT  will be involved in the
    XEROX Grant program.  Dave will be involved in integrating the
    Xerox equipment into the LCS environment.  A PDP-11 based gateway
    between LCSNET and the ETHERNET is contemplated.
    Noel commented that he saw a need for an effort to be made to
    convince groups to use IP rather than invent their own protocols.
 I.  NDRE - Stensby
    NDRE has been assisting in the preparations for the speech demo.
    The protocol status is nearly the same as last reported.  This is
    due to VDH connection problems.  Much work has been done on
    debugging the connection.  Possible bugs have been very difficult
    to track down because we lack control of vital parts of the
    system.  A couple of bugs have been found and corrected in the

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    NORD-10 VDH software without any substantial effect.  The real
    problem seems to be that at certain times when the TIP has sent a
    packet out of sequence, it keeps retransmitting this packet
    instead of retransmitting the packet that is really missing.
 J.  RSRE - Davies
    Brian reported that RSRE has programmed a gateway (based on
    IEN 30) and attempted to bring it up as a catenet gateway between
    UCLNET and RSRENET.  RSRE will be bringing up a host with IP and
    TCP in about a month.
 K.  SRI - Kunzelman, Mathis
    Ron reported that SRI is now operating two PRNETs in the San
    Francisco bay area, and one PRNET at Ft. Bragg, North Carolina.
    The net at Ft. Bragg is now eight terminals on two TIUs, and will
    grow to forty terminals.
    Jim reported that the LDRSRV at SRI-KA which now uses TCP-2.5 will
    be changed to use version 4 soon, tested at BBNF, and installed at
    ISID and ISIE.  Jim is also working on a Port Expander and Mini
    Gateway combined.
 L.  UCL - Kirstein, Jones, Treadwell, Cole, Bennett, Higginson
    Peter gave a brief overview of the UCL effort, then let various
    members of the UCL group give reports on their activities.
    Ron discussed the problems of including network software in a
    small Unix system.  There was also some discussion of port
    expanders and X.25/IP interfaces.
    Steve reported on the situation with the FAX experiment.  The main
    problems seem to be with the timing constraints of the device, and
    matching these to the flow control constraints of TCP.  This
    system currently uses TCP-2.5 but will convert to version 4 soon.
    Bob reported on the development of a "C" to MOS linkage.
    Chris discussed the prototype NIFTP service that allows FTPs from
    EPSS to Tenex and vice versa.  A Unix version of NIFTP has been
    implemented.
    Peter discussed the many flavors of X.25 one finds when building
    X.25/XXX interfaces.

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 M.  IRIA & CELAR - Zimmerman
    Hubert said that IRIA and CELAR would like to explore the
    possibility of cooperative research on the interconnection of
    networks.  IRIA is working on local networks and interconnection
    with TRANSPAC and CYCLADES.
 N.  UNIVERSITY OF ROCHESTER - Lantz
    Keith gave a brief overview of the environment at the University
    of Rochester and indicated the interest in becoming part of the
    internet system.

IV. ACTION ITEMS

 A.  DOCUMENTATION STATUS - Postel
    Jon reviewed the IENs issued since the last meeting.
       IEN     Author          Title
       ---     ------          -----
       108     Plummer         Internet User Queues
          Describes the TOPS20 user interface to the IP.
       109     Strazisar       How to Build a Gateway
          Describes the messages Gateways exchange with each other and
          with hosts, i.e., the Gateway-Gateway protocol.  The main
          focus is on the computation of connectivity and routing
          information.  Replaces IEN 30.
       110     Cerf            Internet Addressing and Naming in a
                               Tactical Environment
          Presents several addressing problems, particularly the
          "flying packet radio" problem.
       111     Postel          Internet Protocol
       112     Postel          Transmission Control Protocol
          The latest editions of the IP and TCP specifications.  Not
          intended to be a change to the protocols but a better
          documentation of them.  Replaces IENs 80 and 81.

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                                                               IEN 121

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       114     Postel          Protocol Options
          Summarizes the option available with IP and TCP.  Replaces
          IEN 92.
       115     Postel          Address Mappings
          Shows how the addresses of various networks are carried in
          the Internet Address format.  Replaces IEN 91.
       116     Postel          Internet Name Server
          Specifies the Internet Name Server, including same new
          features suggested by John Pickens.  Replaces IEN 89.
       117     Postel          Assigned Numbers
          Lists the assigned number for various protocol fields, e.g.
          Networks, Sockets or Ports.  Replaces IEN 93.
       118     Postel          Internet Protocol Handbook
                               Table of Contents
          A one page list of the IENs that specify the current
          internet protocols.  Replaces IEN 94.
       119     Forgie          ST - A Proposed Internet
                               Stream Protocol
          The description of a Internet level protocol for voice
          conferencing.  Includes features for establishing
          multi-addressee connections.
    The discussion that followed suggested several things that should
    be documented.  For example, the higher level protocols (Telnet,
    FTP) should be in the internet protocol handbook, the procedure
    for determining parameters (e.g. retransmission timeout) should be
    documented, what to do in exception conditions should be
    described, testing procedures should be discussed (especially an
    acceptance test).
    Concern was expressed that the new editions of the IP and TCP
    specification were not suitably reviewed by the implementors.  It
    was suggested that a version with changes marked would be useful
    (see Appendix B).

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 B.  EXPECTED DOCUMENTS
    1.  IP Generic Services - Do the two documents 1) the IP Spec by
        Jon (IEN 111), and 2) the Gateway Spec by Ginny (IEN 109),
        supply the information needed?
    2.  SATNET IP Services - Dale McNeill is working with Dave Mills
        (currently the only user).  When the current experiments are
        completed a document will be produced.
    3.  Transition Plan - Vint will discuss the issues in a small
        group meeting and appoint a task force to prepare the plan.
    4.  Host IP Services - Bill Plummer will prepare a document based
        on his talk on How to Build a Host IP.
 C.  XNET - It seems that XNET is not yet fixed to work with IP due to
     a technical disagreement between Jim Mathis and Ray Tomlinson.
     The solution to this is to be reported on at the next meeting.
 D.  Hack IP at SRI-KA and LDRSRV - This is working according to Jim
     Mathis.

V. INTERNET TRAFFIC EXPERIENCE - Davies

 RSRE has conducted some experiments sending messages looped back to
 themselves, with the loopback being located at various places, and
 using several input speeds and block sizes.
 At RSRE there is a multi-terminal TIU with some modifications to
 perform measurements.  The TIU measures the time between the TCP
 segment first being sent and the acknowledgment arriving, a kind of
 round-trip time.
 The path is TIU via 2.4Kb line to PIXIE to PORT Expander to TIP into
 ARPANET. The input was either typing, a 1 octet segment traffic
 generator, or a 128 octet segment traffic generator. Histograms of
 performance under various inputs and loopback points were presented.
 The results indicate lower than expected performance and the
 speculation was that the limiting factor was the program interrupt
 1822 interface (either in PIXIE or the Port Expander).
 It was noted that when two traffic generators were run sending
 segments to each other, ACKs were piggybacked 100% of the time both
 at the TCP level and at the X.25 level (recall the RSRE to PIXIE line
 operates the X.25 level 2 link protocol).

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VI. HOW TO BUILD A GATEWAY - Strazisar

 Ginny discussed the way gateways determine how to do routing.  The
 actual messages used are documented in IEN 109.
 A gateway gathers information on network connectivity by polling its
 network interfaces and known neighbor gateways.  The polling is done
 by sending a message, currently every 30 seconds.  There is an
 algorithm to decide if a net or gateway is up or down based on the
 results of the polling.  The routing algorithm is based on a distance
 measure, a directly connected network is zero distance, an
 unreachable network is infinite distance.  The gateways exchange with
 neighbors their distance tables (substituting infinity in entries
 where the distance to the destination is greater than the distance
 from the neighbor).  Routing information is sent only when something
 changes.  A new gateway can join the system as long as old gateways
 can add a row to their tables dynamically.
 Note that "smart gateways" do all this routing and connectivity work,
 "dumb gateways" do not.  Smart gateways try to route things to other
 smart gateways, but if that can't be done they may fall back to using
 compiled in fixed routes to dumb gateways.
 Danny Cohen suggested that there may be problems with this algorithm
 as the number of networks gets large.

VII. HOW TO BUILD A HOST IP - Plummer

 Bill presented the general flow of processing in a Host IP.  In
 general datagrams arrive from the connected network interfaces.  Any
 fragmented datagrams are reassembled.  Complete datagrams are entered
 into a queue.  Datagrams addressed to other hosts may be forwarded if
 this host is acting as a gaweway, otherwise they are discarded.
 Datagrams addressed to this host are delivered to waiting protocol
 modules or user processes.  User processes or protocol modules may
 create datagrams to be sent, these are queued and based on the
 destination address sent via one of the connected network interfaces.
 During the processing of arriving datagrams several checks must be
 made:
    1.  check the IP version number
    2.  verify the checksum
    3.  see that the length field and the amount received are
        consistent (amount received may be slightly greater due to
        padding)
    4.  check time to live
    5.  assemble fragments

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 When sending a datagram the IP fills in several fields and makes a
 routing decision:
    1.  Insert source address
    2.  Insert any IP options called for
    3.  Insert time to live
    4.  Insert checksum
    5.  Make a routing decision, select an output interface, generate
        local net header and interpret type of service.
    6.  Queue for transmission
 The routing decision can be based on a table of network - gateway
 correspondences.  For each network a gateway on a directly connected
 network is listed.  If the host is notified to use a different
 gateway for that destination network the table can be updated.  If a
 gateway breaks and the host can tell (e.g., receives a "destination
 dead" response)  then switch to an alternate gateway.  It is
 suggested that a heuristic for switching destination gateway is to do
 it when the higher level protocol (e.g., TCP) retransmits a segment.
 (However it is not clear the IP can tell a new transmission from a
 retransmission).
 In the area of congestion control Bill suggests that it is the rate
 that must be controlled which may be considered to determine an
 internet datagram interval.  If a gateway tells a host to slow down,
 increase the internet datagram interval to, say, 130% of its former
 value.  To avoid being stuck at a too large value for the internet
 datagram interval, reduce it to 95% of its former value every 30
 seconds or so.
 There is an issue of fairness in any congestion control.  How can the
 IP properly allocate the available transmission capacity among the
 higher level protocol modules and users?
 The discussion suggested the need for a "Trace Datagram" that causes
 each gateway and the destination host to send back a note, a kind of
 "multi-echo."
 IP modules should provide a handle on the user side to explicitly
 cause a new routing to be calculated.
 The congestion control parameters may be very critical and sensitive.
 Dave Clark has done some simulation experiments and will prepare an
 IEN on this topic.  There may be some interaction between
 source-destination host pairs in this area.

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VIII. STREAMS AND CONFERENCING - Forgie

 Jim presented the proposed ST protocol which is documented in IEN 
 119.  The goals of ST are:  (1) to provide a good base for
 point-to-point and conference packet speech, (2) to support research
 on effective traffic control techniques, (3) to support a
 demonstration of cost-effective speech, and (4) to operate as an
 extension of internet protocol.
 Jim indicated four requirements and corresponding approaches for
 meeting them:  (1) guaranteed data rate - know requirement in advance
 and assign loads to links statistically, (2) controlled delay
 (predictable dispersion) - prevent congestion by controlling access
 on a call basis, (3) small quantity of speech per packet - use
 abbreviated header and aggregate small packets for efficiency, and
 (4) efficiency equal to or better than circuit switching without TASI
 (packet efficiency * link utilization > 45%) - abbreviated headers
 for packet efficiency and high link utilization with effective
 traffic control.
 One of the key decisions is to consider ST connections to be full
 duplex.  The claim is made that this allows faster connection setup
 for conferences.  There was some discussion on this point and the
 issue will be examined further.
 Another issue is the sharing of transmission capacity between speech
 (ST) and data (IP) in the internet.
 Also discussed was the identification of the route by a list of
 gateways rather than by a list of networks.  The resources to be
 reserved are controlled by networks not gateways.
 One very interesting feature of ST is its mechanism for flexible
 multi-addressing and routing of messages such that each addressee
 receives at most one copy of a message.
 Jim presented the message formats and worked through an example of
 connection setup.  There was some concern expressed about the effects
 of delayed duplicate control messages, and how ST operates under
 failure conditions.  Also concern that several conference setups in
 competion may result is a deadlock similar to reassembly lock up.

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IX. SOURCE ROUTING & PROTOCOL MULTIPLEXING - Cohen

 Danny reviewed the proposed source routing procedure described in
 IEN 95.  This mechanism provides a list of addresses for the datagram
 to pass through.  Normal routing is used to move the datagram between
 these points.  The route information for sending a datagram from A
 through B and C to D is expressed by A as TO: B, SR: C,D.  At B this
 is changed to TO: C, SR: D, and at C it is changed to TO: D.  The key
 is that the next address must be interpretable at the point it is
 used.  This means that local (rather than internet) addresses may be
 used.
 The discussion focused around the issue of non internet addresses in
 the source route and how (if at all) to mark them.  It seems
 desirable to let a source route contain any of the following in any
 order:
    1.  Internet Address.
    2.  Local Address (prefixed with an escape code and a length).
    3.  Network Address (Network part only).
    4.  Here - an address value that means this host, this net (or any
        host, or every host).
 Alternately one could have each address in the source route have a
 prefixed "op-code" that indicates what kind of address it is.
 Danny did not discuss the multiplexing of protocols (due to time
 pressures) but urged everyone to review IEN 90.  It appeared that the
 multiplexing protocol was accepted (at least in principle).

X. GATEWAY MONITORING & CONTROL CENTER - Flood Page

 David described the GMCC organization and the types of information
 that will be reported.
 The operation is much like the ARPANET NCC except that gateways are
 the objects of interest rather than IMPs.
 Gateways will communicate with a set of monitoring and control
 processes (running on a TOPS20 somewhere).  These monitoring and
 control processes will update a central data base.  The data in this
 data base may be accessed by Terminal Processes (i.e., User Interface
 Programs).
 A terminal process may take control of a gateway, but a gateway may
 only be controlled by one terminal process at a time.
 Three types of controls may be exercised:  start or stop reports,
 inquiries, enable or disable traps.  The reports give throughput

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 statistics and interface up/down status.  The inquiries give the
 gateway description (name, connectivity), echo response, or routing
 data.  The traps give changes in the interface up/down status, or
 neighbor gateway up/down status.
 The information stored for each gateway in the central data base
 includes:  the latest regular report, the interface address, the
 neighbor gateways, the reporting and trap status, the gateways own
 up/down status, and the process currently controlling the gateway (if
 any).
 In the future the GMCC will provide summary reports on traffic and
 up/down status.
 Other future topics are Performance Measures, Higher Level Fault
 Diagnosis, Accounting Information, and inclusion of information from
 NCCs.
 To use the GMCC facilities one would login to the GMCC host and run a
 terminal process.  There was some discussion of the access control on
 people taking control of gateways.  Also some concern about the
 artifact introduced into the measurement by accessing the GMCC via
 the gateway being measured, and also the effect on other gateways (or
 their statistics) of relaying the measurement messages to the GMCC
 host.
 David will prepare reports on:  (1) GMCC Message Formats, (2) How to
 use a Terminal Process.

XI. DISCUSSION OF SPEECH DEMO - Forgie

 Jim described the configuration for the speech demo.  There are four
 sites involved:  Lincoln Laboratory and ISI on the ARPANET and NDRE
 and UCL on the SATNET.  There is a special purpose gateway at BBN.
 This gateway is a PDP 11/34 ELF system.  The basic data rate for one
 site is 5 packets/sec, at this rate the gateway must handle 15
 packets/sec.
 In the ARPANET section of the conference the mode of operation is
 centralized control and distributed data.  In the SATNET section the
 mode is distributed control and distributed data.  The SATNET section
 uses a SATNET shared stream.

XII. DISCUSSION OF FAX SYSTEM - Treadwell

 Steve described the configuration and operation of the FAX-Network
 system.  The FAX machine is a DACOM 6000.  It is connected to an
 LSI-11 (MOS operating system).  The LSI-11 contains an interface to

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 the DACOM, a TCP, and a controlling program.  The controlling program
 interacts with a user at a display terminal.
 There is also a server FAX program on BBNC that accepts input and
 stores it in the file system, or on request sends stored FAX data
 from the file system.
 The operation is for the user to type on the controlling programs
 terminal a request to send FAX data to a file.  A TCP connection is
 established between the LSI-11 and FAX server at BBNC.
 Pages are input through the DACOM and data is sent to BBNC and stored
 in the file.  To move FAX data from the file to paper, the user
 enters a retrieve request on the controlling programs terminal.
 This system currently uses TCP-2.5.  The next step will be to convert
 to using version 4.  Also to change the address so the transmission
 will be through an internet gateway.
 There have been several problems in getting this working.  Primarily
 the timing requirements of the DACOM and the flow control of TCP.  A
 typical page results in 300,000 bits (with wide variance).  The DACOM
 sends 585 bit blocks and if not accepted with in 6 seconds aborts the
 page.  The total transmission path must support at least 100 bits/sec
 on the long term average.
 ISI is getting a RAPICOM 450 FAX machine and will use it in a similar
 way.  (A RAPICOM 450 and a DACOM 6000 are identical machines).  At
 ISI the FAX machine will be treated as a device (a peculiar terminal
 on TOPS20) rather than as a host.

XIII. ADDRESSING ISSUES - Cerf

 Vint described several situations where a host may have several
 possible addresses and may wish to change between them dynamically
 without losing ongoing communications.
 A host may be dual (or multiply) homed, i.e., have two (or more)
 interfaces to the same net.  A host may be connected to more than one
 net.  Or a host may change nets.
 This last case is illustrated by a flying packet radio, passing over
 a series of ground PRNETs each connected to the internet via a
 gateway.  The flying packet radio is for a time in the range of
 PRNET-1, then passes out of that range into the range of PRNET-2,
 etc.
 Another problem is partitioning.  That is a network breaks into two
 (or more) parts which continue to function independently.  Can a host

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 in one part communicate with a host in another part via gateways and
 other networks?
 Does source routing solve the partitioning problem?  Or is a scheme
 needed to dynamically assign unique addresses to each partition so
 that the ordinary gateway dynamic routing will solve the problem?
 Another proposal is to drop the requirement that connection be
 identified by the total address.  By using only the pair of ports to
 identify a connection one could accept as a continuation of a
 conversation messages from a different host if it had the same pair
 of ports (and the expected sequence number).

XIV. PARTITIONING - Plummer

 Bill discussed the problems of multiply connected hosts.  If a host
 is connected to two networks, which are also interconnected via
 gateways, the host has alternate routes to use in sending messages.
 The internet gateways can exchange connectivity information.  A
 multiply connected host cannot take full advantage of this without
 being a gateway itself and calling the host a network.  Another
 problem is for a destination to answer a message from a multi-
 connected host.  The multi-connected host would like to allow any of
 its interfaces to be used to receive the reply.  To do this it could
 use a pseudo network number and act as if those interfaces were
 gateway connections.
 This use of network numbers for pseudo nets may use up the network
 numbers too quickly.  Bill proposes what he calls host-group routing
 which uses a 32 bit address as if it were a network number.  A host
 chooses one of its internet addresses as its "name".  Gateways treat
 that name as a network name for connectivity and routing purposes.  A
 mask can be used to allow groups of hosts to be routed based on one
 entry.  Bill gave an example of how this might work and showed a
 routing table for a pseudo net at BBNC.
 This topic is to be discussed again at the next meeting.

XV. RIG - Lantz

 Keith reported on the network environment at the University of
 Rochester.  The key is a multi-machine multi-net system started in
 1974.  All communication between processes in this system is via
 messages.  The system is based on Feldman's experience and other
 papers on message communication.
 The equipment involved includes:  4 Altos, 2 Eclipses, an Ethernet, 9
 terminals, 1 PDP-10, 1 VAX, and an ARPANET.  The applications
 include:  editing, compiling, file management.  An important

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 development is the virtual terminal model, which allows several
 processes to interact with a terminal using multiple possibly
 overlapping windows.
 The process level communication involves a name to address conversion
 by lookup in a name server, and an address to route conversion
 supported by a local kernel and network communication modules.  Three
 communication styles are supported:  atomic transactions, connections
 or streams, and asynchronous messages.
 One problem area is protocols.  There are too many:  U of R Ethernet,
 PARC Ethernet, ARPANET, DECNET, internet.  Can all these live in
 harmony?

XVI. SUMMARY OF SMALL GROUP MEETINGS

 1.  PERFORMANCE MEASUREMENT SMALL GROUP MEETING - Kunzelman
    This group discussed the need for performance measurements of the
    internet protocols at all levels.  The group reviewed the current
    work, discussed performance metrics, measurement tools, and
    documentation of measurement methods and results.
    The group recommends that specifications of performance measures
    for IP and TCP be written, that a set of tests for IP, TCP, and
    higher level protocols be defined, and that a bibliography on
    performance measurement be prepared.
    Please see Appendix C for further detail on this group meeting.
 2.  UNIX SMALL GROUP MEETING - Cain
    Three topics were addressed in the UNIX small group meeting:
    1. Use of network UNIX on small PDP-11's
       (specifically, the 11/34 and the 11/40).
    2. MOS work on UNIX systems.
    3. Use of UNIX on VAX machines.
    For PDP-11's which do not support the separation of instruction
    and data space, incorporating the widely distributed NCP programs
    into the UNIX kernel usually produces an object which is barely
    small enough to boot, even after greatly reducing various system
    parameters. Processes like TCP and Telnet have to share the scarce
    remaining space, and are bound to perform poorly because of
    swapping. Noel Chiappa is about to obtain, from NOSC, a version of
    UNIX which has no disk buffers in the kernel data space, and will
    attempt to install the NCP kernel software. Performance of this

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    version of UNIX is uncertain, but a mailing list (see Appendix A)
    has been established for those interested in the outcome.
    UCL, MIT, and BBN are all interested in doing MOS work in a UNIX
    environment. The problem is that there is a variety of file types
    (a.out, .obj, .rel, .lda) which must somehow be combined into an
    object which is loadable into an LSI-11, and is understandable by
    DDT or a similar debugger. UCL has "C" interfaces to MOS system
    calls and some utilities which Noel Chiappa will attempt to put in
    a "nice" UNIX environment, and make them available for others. A
    mailing list (see Appendix A) was established for those who wish
    to follow his progress.
    Keith Lantz discussed a meeting with ARPA, Rochester, CMU, and
    others associated with ARPA-funded research involving VAX
    machines. At the meeting, the decision was made to use UNIX on the
    VAX machines, specifically the version of UNIX modified at
    Berkeley to take advantage of the VAX paging hardware. The source
    of support for the VAX UNIX is not yet named. Rochester and CMU
    are both interested in implementing TCP and IP on their VAX
    machines. A mailing list (see Appendix A) was established for
    those interested.
 3.  TCP VERSION 4 AND TIU SMALL GROUP MEETING - Haverty
    The small group meeting on the status of the new TCP
    implementation and TIU also covered some general issues of TCP
    support for MOS-based systems in general.
    Jim Mathis reported that recent work on the MOS TCP version 4
    implementation involved separating the code into individual
    modules, to isolate the network- and operating-system-dependent
    sections of the code. The major part of the TCP code is now in the
    TV4PRO module.   Operating system support code exists in TV4MOS or
    TV4ELF, depending on the operating system involved.   The
    "released" versions of this implementation are available on the
    SRI-KL machine in the MOS-DEVEL directory, but they will be moved
    soon to PKT-LSI-11.
    Ongoing work with the TCP involves addition of an internet layer
    which will be accessible to user processes using entry points to
    be defined.  This will occur in a later release of the software,
    which is not expected to involve any changes to the TCP interface
    to user processes. The internet layer will also implement some of
    the gateway-gateway protocol functions.
    In addition, the software can be extended to support multiple
    hardware interfaces, to permit multi-homing of hosts on multiple
    networks. This work however is not yet in progress.

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    The discussions which followed identified a need for two new
    mechanisms within the user community.  The first is simply an
    announcement mechanism, to inform users of the SRI software of new
    releases, the changes which have been made, functions added, and
    location of the code itself.   A second mechanism involves
    integration of changes developed at user sites into the
    SRI-maintained sources.  For example, software to support other
    network types must be done at the site running the network, but
    should then be integrated into the standard sources.
    Because of the need for sites other than SRI to implement
    network-interface software, the internal interface between the TCP
    and internet layer and the local-net module must be clearly
    defined and stabilized.  MIT is likely to be the first site to
    implement a new local-net module.
    Further discussion explored details of the functionality of the
    existing TCP implementation, and requirements which various user
    projects expect to have in the future.   Some of the facilities
    not yet implemented include:
       o ability to have multiple connections in one MOS process
       o reassembly of internet fragments
       o full processing of EOL
       o processing of "rubber EOL"
       o user access to URGENT functions
       o full functionality at the Telnet user interface
    The last area explored identified the need for additional work on
    the Telnet implementation, to, for example, provide the ability to
    send remote RESETs.
    A short discussion of "coming attractions" followed, including the
    following expected changes:
       o internet layer in Bliss, probably by the end of 1979
       o use of the internet name server by Telnet
       o XNET server within MOS, to debug MOS processes remotely
    The TCP software is currently written in MACRO-11.  It is a
    candidate for conversion to Bliss, but this will not be done until
    the Port-expander software is converted.
    One possible performance limitation was identified during the
    discussion.  Currently, data is ACKed when it is accepted by a
    user process.  Since this can be significantly later than the
    actual receipt of the data from the network, throughput might be
    improved by modifying the TCP to ACK data on receipt from the
    network.

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    A short discussion of TIU issues identified the need for
    determining how many terminals can be supported by a TIU at once,
    in two cases.  In a heavy-use situation, the limitation on number
    of active, high-throughput terminals should be determined.  This
    number is probably limited by the raw speed of the LSI-11, and may
    be increased by conversion to faster hardware such as the
    PDP-11/23 when it is available.  A second case involves the
    limitation on support of low-usage terminals.  This limit involves
    primarily how many serial interfaces can be connected to the
    LSI-11 and configured in the packaging.
    The meeting also demonstrated a need for better interchange of
    information among the participants and general community of users
    of MOS, TIUs, and related hardware and software.  A mailing list
    is being set up, called MOS-TCP, for this kind of activity (see
    Appendix A).
 4.  LONDON-NORSAR LINE AND SATNET SMALL GROUP MEETING - McNeill
    Dale said that loading of the Goonhilly SIMP and the london TIP
    over the satellite channel is operational.  Monitoring and control
    paths exist for all SIMPs; sufficient backup paths exist through
    use of the satellite channel and gateways connected to other
    SIMPs.
    Vint announced that beginning January 1, l980, the NORSAR-SDAC
    circuit will become a military circuit for operational data only.
    Seismic data traffic from the NORSAR TIP will continue to be sent
    on this line.
    Funding for the London-NORSAR circuit ceases October 1, 1979.
    Peter anticipates that the ARPANET direct connection circuit via
    SATNET (line 77 between London and SDAC) will be needed to provide
    ARPANET connectivity to the London TIP until some time after
    October l980.  This circuit will continue to provide ARPANET
    service to the Rutherford Lab, EPSS, and the London TIP.  The
    long-term goal is to have internet service to London only using
    the UCL gateway attached to SATNET. Prerequisite is a change of
    the London TIP to a host (TCP TIP).  The mechanism of internet
    loading and support of London machines must be developed.
    In conflict with the maintenance of operational service to London
    is the introduction and checkout of PSP Terminals, the checkout
    and release of new SIMP software, and the checkout and performance
    of the NTC demonstration.  Hardware and software development will
    be restricted to after 1400 EDT, while operational service will be
    maintained from 0200 to 1400 EDT, daily.

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 5.  NTC DEMO PLANNING SMALL GROUP MEETING - Mills
    The principal results from that meeting were a revised plan for
    network connectivity and a change in the way speech would be
    handled. Specifically, it was decided that Jim Forgie's software
    would be used in the BBN and UCL gateways with the LPCM operated
    from Washington via appropriate data lines to the BBN Gateway. Jim
    has already made provision for this in the LPCM design, but it has
    not been operated in this mode before.
    Datagram traffic for the Demo is planned to be sent via
    Clarksburg, with a backup to Etam via a backdoor connection via
    the Clarksburg SIMP internal gateway and the RCC or other suitable
    hack. UCL will participate in the Demo from London with live
    speech and fax. Participation by NDRE will depend on a PSP
    Terminal being installed there.
    Jim mentioned a couple of minor problems with the LPCM hardware.
    Correcting these will probably involve sending ROMs to the various
    sites. There is a question of Gateway reliability which leaves all
    of us nervous
 6.  IP/TCP FLOW CONTROL SMALL GROUP MEETING - Clark
    This meeting was a fairly informal discussion among the
    implementors of TCP and gateways. Several topics were discussed.
    1) How to manage RFNMs on internet link.
    2) A simple simulation of a host responding to quench messages.
    3) How to perform quenching experiments, given the current level
       of internet operation.
    4) Should the TCP-IP or application-TCP interface be
       specified/standardized with respect to flow control?
    While the discussion was fruitful, no substantial conclusions were
    drawn.
 7.  X.25 GATEWAY SMALL GROUP MEETING - Binder
    The purpose of this meeting was to review various factors
    impacting the development of an ARPANET/X.25 gateway using an
    LSI-11 to provide a 50 Kbps full duplex service. The meeting
    basically covered only the issue of hardware interfacing to the
    X.25 network. Three different interfaces were discussed: a
    byte-interrupt device, a non-DMA packet-interrupt device, and a
    full DMA device.
    The byte-interrupt interface and related level 2 and 3 X.25
    software has been developed by UCL and is now available for use.
    Although precise throughput measurements have not yet been made,

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    experience with the LSI-11/MOS system by meeting attendees
    indicated that a byte-interrupt configuration would not achieve 50
    Kbps full duplex operation. In particular, measurements by SRI
    have indicated a maximum of about 50 Kbps through a looped-back
    1822 byte-interrupt interface on a MOS system running only a
    message generator (no gateway or second network interface).
    The packet-interrupt interface is being developed by RSRE, and
    along with level 2 software is expected to be checked out in 6-8
    weeks. This interface contains 4K bytes of buffering, shared among
    input and output. Operation consists of copying packets between
    the interface memory and main memory, with a single interrupt
    associated with each packet.
    UCL plans to develop a full DMA interface, but this is not
    expected to be available until anywhere from 8 to 12 months from
    now.
    A framing issue presently exists in that both IPSS and Telenet
    X.25 networks now use bi-sync framing. However, both are expected
    to make HDLC bit-oriented framing available this fall.
 8.  PORT EXPANDER SMALL GROUP MEETING NOTES - Davies
    1.  Hardware Delivery Outlook.
       SRI has fifteen systems on its order book and enough components
       to build only two complete ones at this time.  Some of the
       hardware bottlenecks are:
          a) Boxes from DEC - deliveries up to January '80.
          b) Low power Schottky chips for 1822 DMA boards.
          c) Cable connectors for 1822 units - Amphenol.
          d) Control Panels.
       Delivery of port expander units would continue at a slow rate
       at least until the end of the year with Vint Cerf nominating
       the recipient of each system as it rolls off the production
       line.
       A postscript on the hardware discussion concerned the
       robustness card which may have to be reprogrammed for automatic
       loading from nets which are not on the ARPANET. The robustness
       card uses UV erasable PROMS. Mathis said that there would be
       documentation supplied with the robustness card indicating how
       this should be done. The cards themselves were just coming back
       from the printed circuit facility and although one or two types
       of chip for this board were in short supply, it was hoped that
       board delivery would begin at the end of September.

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    2.  Software Developments.
       Most of the discussion centered around the new facilities which
       would be offered with the SRI supported BLISS-11 version of the
       PORT Expander code. Some of these features are:
          a) Provision of NOP handling.
          b) Provision of IMP padding.
          c) Flow control facility.
          d) Facility to simulate RFNMs internally.
       There were still some open ended problems like what  should a
       port expander do when the NCP host crashes. One possible
       approach is to offer two different solutions to this problem
       and select one at configuration time.
       Possible release dates for the BLISS-11 version of the port
       expander were mid October if Mathis can get an IMP port for
       debugging or up to a month after depending on the priority of
       the work.
       Finally Strazisar joined the meeting for a discussion on
       integrating the mini-gateway code and port expander code into
       the same machine. Clark suggested that this integration problem
       would become almost trivial if someone wrote a null 1822 driver
       under MOS which allowed buffers to be passed across the driver
       without copying. Strazisar volunteered to take a debugged copy
       of Mathis' port expander code and integrate it into the
       mini-gateway with an optimistic delivery date of the End of
       November.
 9.  TCP IMPLEMENTATION SMALL GROUP MEETING - Cerf
    The discussion focused on the changes to IP required by DCA to
    satisfy the DOD security and precedence needs.  The existing IP
    option for S/P/T does most of what's needed, but in addition the
    TOS field will be redefined slightly to be:
        0 1 2 3 4 5 6 7
       +-+-+-+-+-+-+-+-+
       |     |S|   |S|S|
       | PRC |/|Rel|/|P|
       |     |D|   |R|D|
       +-+-+-+-+-+-+-+-+
    That is:
       Bits 0-2:  Precedence
       Bit 3:     Stream or Datagram
       Bits 4-5:  Reliability
       Bit 6:     Speed or Reliability

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       Bit 7:     Speed
    This information has to be passed up and down the layers of
    protocol.  Enforcement of the security and precedence is up to
    each host.  There needs to be a specification of how to interpret
    and implement these functions.  Preemption rules must be specified
    too, for the higher level protocols.
    There was some discussion of the unauthorized use of security and
    precedence features.  The basic rule is to act on it speedily now
    and to log the header of the message so one can ask later if the
    originator was authorized.
 10. TCP APPLICATIONS SMALL GROUP MEETING - Postel
    This group discussed problems in programming application programs
    that use TCP.  Postel had a problem figuring out how to use the
    user/TCP interface (JSYSs) to create a successful TCP using
    program.  The problem may be with the documentation.  Haverty has
    the problem that programs don't work but don't crash either.
    Clark said his TCP can't tell the user anything more specific than
    "it didn't work."
    What is needed is better documentation, fault isolation tools, and
    user level debugging aids.  Also a memo on what is available,
    e.g., a traffic generator at BBN-UNIX.
 11. ST PROTOCOL SMALL GROUP MEETING - Hoversten
    This group first made up a detailed agenda of issues to discuss.
    In general the topics included:
       Connectivity
       Routing
       Stability
       Protocol Layering
       Resource Allocation
       Information Exchange
    Further discussion of the role of ST in resource allocation is
    needed.  It is agreed that ST provides a structure to support
    multi-addressing and a resource allocation policy.
    The relationship of ST to IP is that ST is experimental, will be
    implemented at a small number of sites, and will have IP imbedded
    in it.

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 12. 1822 BOARD PROBLEM SMALL GROUP MEETING - Mathis
    The problem with 1822 boards is being worked on at SRI.  Software
    for the TIU which circumvents the problem will be made available.
    A hardware fix is being studied.

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XVII. AGENDA FOR NEXT TIME

 The next meeting is February 4-6 at SRI International in Menlo Park.
 Ron Kunzelman is the contact.
 Agenda Items:
    1.  Kirstein, Davies, Frankel - Internet Performance Experience
    2.  Flood Page - Longterm Gateway Statistics
    3.  Cerf - Schedule & Milestones Review
    4.  Forgie - ST Protocol
    5.  Cohen - ST Performance
    6.  McQuillan - Internet Routing
    7.  Cain, McFarland, Cerf - IP/TCP Acceptance Testing
    8.  Plummer, Tomlinson - Higher Level Protocols FTP & Integration
                             with TCP
    9.  Postel - Internet Message Handling Interim FTP Based Multi
                             Media Supporting
    10. Deutsch - BBN - FAX & Text Message System
    11. Cerf - Multi Homing & Partitioning
    12. Plummer - Host Group Routing
    13. Demos:
       A.  GMCC Monitoring - Flood Page
       B.  Fault Isolation in TIU - Mathis
       C.  Internet Message Transport - Postel
 Action Items:
    1.  Milestones - each contractor is to provide a list of
        milestones to Cerf.  The intention is to quantize tasks and
        identify increments in capability.  The goal is to make
        progress easily detectable.  The combined milestones will be
        distributed to the internet group, and will be reviewed at the
        next meeting.

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    2.  Monthly Reports - each contractor is to provide a monthly
        report to Postel.  The report should note accomplishments,
        progress on milestones, unusual events, problems.  A summary
        of all reports will be distributed to the internet group.
    3.  XNET - to be converted to version 4 by Jim Mathis and Ray
        Tomlinson.
    4.  Host IP Document - Bill Plummer is to write an IEN on how to
        build a host IP.
    5.  GMCC - David Flood Page will write an IEN on GMCC message
        formats and an IEN on how to use a terminal process .
    6.  Congestion Control - Dave Clark will write an IEN on
        simulation experiments in IP congestion control.
 Future Meetings Schedule
    1980
       FEB - SRI
       MAY - MIT
       SEP - RSRE
    1981
       JAN - ISI
       MAY - ARPA
       SEP -UCL

XVIII. DOCUMENTS DISTRIBUTED

 IEN        Author       Title
 ---        ------       -----
 109        Strazisar    How to Build a Gateway
 110        Cerf         Internet Addressing and Naming in a Tactical
                         Environment
 119        Forgie       ST - A Proposed Internet Stream Protocol

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XIX. ATTENDEES

 Vint Cerf                ARPA               Cerf@ISIA
 Robert E. Kahn           ARPA               KAHN@ISIA
 Dick Binder              BBN                BINDER@BBNE
 Jack Haverty             BBN                JHAVERTY@BBND
 Dale McNeill             BBN                DMCNEILL@BBNE
 David Flood Page         BBN                DFLOODPAGE@BBNE
 William Plummer          BBN                Plummer@BBNA
 Virginia Strazisar       BBN                STRAZISAR@BBNA
 Hoi Y. Chong             COMSAT             Mills@ISIE
 David Mills              COMSAT             Mills@ISIE
 Chip Bumgardner          CTEC               CHIPS@BBNC
 Jack Hammett             DARPA-IPT          Hammett@ISIA
 Ed Cain                  DCA                Cain@EDN-UNIX
 Ray McFarland            DoD                McFARLAND@ISIA
 Michel L. Audren         French Ministry    Observer
 Dominique A. Truchetet   of Defense         Observer
 Hubert Zimmerman         IRIA               HZim@BBNC
 Danny Cohen              ISI                Cohen@ISIB
 Jon Postel               ISI                Postel@ISIB
 Estil Hoversten          Linkabit           Hoversten@ISIA
 Noel Chiappa             MIT                JNC@MIT-AI
 Dave Clark               MIT                Clark@MIT-MULTICS
 Jim Forgie               Lincoln Lab        FORGIE@BBN
 Frank Deckelman          NAVELEX            DECKELMAN@ISIA
 Aage Stensby             NDRE               AAGE@SRI-KA
 Andrew Bates             RSRE               RSRE-T4@ISIA
 Brian Davies             RSRE               RSRE-T4@ISIA
 Allan J. Fox             RSRE               RSRE-T4@ISIA
 John Laws                RSRE               RSRE-T4@ISIA
 Ron Kunzelman            SRI                KUNZELMAN@SRI-KL
 Jim Mathis               SRI                Mathis@SRI-KL
 Robert Cole              UCL                UKSAT@ISIE
 Sunil K. Das             UCL                PKT-UCL@SRI-KL
 Peter L. Higginson       UCL                UKSAT@ISIE
 Andrew Hinchley          UCL                UKSAT@ISIE
 Ron Jones                UCL                UKSAT@ISIE
 Peter Kirstein           UCL                Kirstein@ISIA
 Alan J. Mayne            UCL                UKSAT@ISIE
 Steve Treadwell          UCL                UKSAT@ISIE
 David Lloyd              UCL/UKMOD          LLOYD@ISIA
 Keith A. Lantz           U of R             LANTZ@SRI-KL

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APPENDIX A

 The following special interest group mailing lists have been set up
 by Noel Chiappa at MIT-ML.  To use them, send to <group>-PEOPLE at
 MIT-ML [or just <group> (DON'T include the "<"'s)].
 If you want to be on one or more of these mailing lists please send a
 note to Noel, JNC@MIT-AI (not to the whole group).
 If you get a message from Person and to a mailing list, DO NOT send
 your reply to the mailing list AND Person; the MIT-ML mailer isn't
 smart enough to notice and will send duplicate copies to Person.
    MOS-UNIX             MOS support on UNIX
    SMALL-UNIX           UNIX on small machines
    VAX-UNIX             UNIX on VAX
    MOS-TCP              MOS, TIU and the MACRO-11 TCP
    MOS-PE               Port expander / Minigateway
    NET-UNIX             Network support on any UNIX

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APPENDIX B

 IP and TCP Specification Differences
 The following is a brief description of the difference between IEN-80
 and IEN-111 (IP), and between IEN-81 and IEN-112 (TCP).
 In both cases the new documents are intended to simply be better
 documents, and no significant changes to the protocols are intended.
 There are many minor changes of wording, punctuation, or spacing, so
 that a source compare would catch many many paragraphs in which there
 is no significant change.  It is intended that the text added (or in
 some cases deleted) lead to an easier to understand description of
 the protocols.
 IP Differences
    1. A much more specific description of a fragmentation and
    reassembly procedure is included.
    2. Some Options are changed or added:
       a. Three options are added for use by the BCR protocol.
       b. A Stream-ID option is added.
       c. The Source Route option is changed to conform with IEN-95.
       d. The Return Route option is added to conform with IEN-95.
       e. The Error Report option is expanded to have several specific
       error codes., and a standardized IP header for error reporting.
 TCP Differences
    1. Two additional States are introduced in the connection closing
    sequence.
    2. The EOL sequence number fixup procedure is changed to be based
    on remembering the sequence number of the beginning of the most
    recent buffer rather that the initial sequence number of the
    connection.
    3. In many cases the RST is not required to acknowledge that
    segment that caused the reset to be generated, and in many cases
    it is not necessary to check the ACK value to verify a RST.

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 APPENDIX C
    Minutes of Internet Subgroup Meeting for Performance Measurement
    Present:  Ron Kunzelman (SRI) (Chairman), Noel Chiappa (MIT),
    Brian Davies (RSRE), Stephen Edge (UCL), David Flood Page (BBN),
    Andrew Hinchley (UCL), Ron Jones (UCL), Bob Kahn (ARPA), Peter
    Kirstein (UCL), Alan Mayne (UCL) (Minute-taker), Ray McFarland
    (DOD)
    Kunzelman pointed out that there is need for performance
    measurement at different levels of protocol, including
    measurements on Telnet and FTP at the user level, TCP at the
    transport level, and datagrams at the internet level.  The meeting
    then considered various specific aspects of measurement.
    Measurement Work Now Being Done or Being Planned
    BBN (Flood Page) will do some performance measurements at the
    datagram level on traffic passing through gateways; no tests are
    envisaged.  The BBN gateway will monitor IP traffic going through
    the gateway.  BBN is looking at CPU utilization, and can also
    extract interface information by address pairs.  BBN (Wingfield)
    is doing some performance tests on TCP.  Throughput and delays
    have been investigated.
    SRI is measuring Telnet throughput (bits/sec) from TOPS20 and
    TENEX hosts.
    UCL is trying to time FAX transmissions, and NIFTP transmissions
    at the user level.  UCL would like to measure individual
    performances end-to-end, to see if there is any destructive
    interference.  For ARPANET-SATNET-ARPANET transmissions, there is
    a need to know the best ARPANET performance, the best gateway
    performance, and the best Satnet performance, and then compare the
    combination of these with the best actual ARPANET-SATNET-ARPANET
    performance, to see whether they are comparable or differ by an
    order of magnitude.
    RSRE (Davies) has previously measured with old PIXIE, and would
    now like to repeat some of these measurements with new PIXIE.
    Measures have been made of round-trip TCP ack times.  The
    measurement techniques consist mainly of turning the traffic
    generator on for about five minutes at a time, then obtaining a
    delay histogram.

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    Performance Metrics
    The following metrics have been used to measure ARPANET
    performance:
       1.  ARPANET has problems of low bandwidth, hence uses
           throughput metrics such as packets/sec and user-bits/sec.
       2.  SATNET has long delays, hence measures mean transmission
           time.
       3.  PRNET is liable to high loss, hence measures the percentage
           of missing packets.
       4.  Packet efficiency is the ratio of information packets
           received to total packets received (the difference being
           due to control and retransmission overhead).
    Kirstein stressed the need for better individual metrics, and then
    for developing algorithms for combining them.  For example, both
    bits/sec and packets/sec are important.
    He also raised the question of how the performance varies when
    going through different combinations of networks.
    Measurement Tools
    Tools currently being used in Arpanet include:
       1.  At the user level, FTP + "stopwatch" for bandwidth and
       Telnet + "stopwatch" for measurements of remote echo time and
       bandwidth.
       2.  Timestamps in pickup packets.
       3.  Echo server in gateways.
       4.  Traffic generators and sinks.
       There is also a possibility of using synchronized clocks to
       measure one-way times and asymmetric delays as well as round
       trip times.  Hinchley is looking at interval times between
       successive packet streams, as a method of measuring delays.
    Measurement Needs
    Kunzelman pointed out that there is currently no measurement at
    the transport level in the ARPANET.  Statistics are needed for the
    distribution of user traffic, which can be measured on entry to

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Internet Meeting Notes

    the internet system.  There is also a need to have statistics for
    the distribution of packet sizes.
    More measurement is needed of round-trip TCP ack times:  so far,
    this has been done only by RSRE.  Also in TCP, measurements are
    needed of retransmissions and checksum errors.  TCP-specific
    measures should be separated from general network and gateway
    measures, although such separation might be difficult to achieve
    in practice.
    Mayne would be grateful to anyone who would send him empirical
    data that would be useful to help validate his proposed simulation
    and theoretical studies, especially on problems of joint
    ARPANET-SATNET operation.  It was pointed out that McQuillan has a
    large amount of empirical data.
    Some Problem Areas
    Kahn pointed out the need to isolate problem areas, such as
    optimization and tuning, for which measurements are needed.  Some
    of these problems relate to research and development about
    networks, including obtaining insights about their behavior,
    others are concerned with the operational control of networks, and
    there is also the problem of persuading some network users that
    they actually have problems!
    Kirstein said that a big problem is to put uniform methods of
    measurement into the internet environment; this is very difficult
    and requires much thought.
    Kahn asked if we could do absolute performance measurements, or
    whether they are all relative.
    Kahn said that measurements could contribute to the understanding
    of various problem areas, for example:  performance tuning and
    other parameter optimization, retransmission strategies,
    alternative routing strategies, minimum delays for
    interactive-type traffic, cost considerations, robustness and
    recoverability.
    Mayne mentioned two important incentives for carrying out
    comprehensive measurements:
       1.  Validation of simulation runs and theoretical models.
       2.  Obtaining insights into what is happening, especially in
       network operating problems of crucial practical importance.

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Internet Meeting Notes

    Documentation
    Mayne said that is would be valuable to prepare a comprehensive
    list of all documents relevant to network measurement, including
    papers on methods and tools, measurement software and write-ups of
    that software, and collections and summaries of actual performance
    data.  He suggested that each organization participating in the
    internet, should contribute relevant entries, and he himself will
    prepare an annotated bibliography of relevant UCL literature.  He
    is also willing to act as a mailbox for collecting information
    from the other organizations.
    It was pointed out that important documents in this area have been
    written by Kleinrock, McQuillan, and Wingfield, and also at UCL.
    Recommendations for Further Action
       1.  Study network performance in relation to types of network
       subsystem, including network as a whole, gateways, hosts,
       operating systems.
       2.  Write specifications of performance measures for TCP (it
       was suggested  that this might be done by Wingfield), user
       level protocols, and IP.
       3.  Define a set of tests for IP, Datagram, TCP, higher level
       protocols, etc.
       4.  More work needs to be done on IP, for example, using GGP
       and echo packets and measuring round trip times, also
       investigating loss rates including numbers of duplicate packets
       and packets out of order.
       5.  Prepare and adequate bibliography of documents on
       performance measurements, and keep it up to date.

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