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rfc:rfc2340

Network Working Group B. Jamoussi Request for Comments: 2340 D. Jamieson Category: Informational D. Williston

                                                               S. Gabe
                                        Nortel (Northern Telecom) Ltd.
                                                              May 1998
         Nortel's Virtual Network Switching (VNS) Overview

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 (1998).  All Rights Reserved.

Abstract

 This document provides an overview of Virtual Network Switching
 (VNS).
 VNS is a multi-protocol switching architecture that provides COS-
 sensitive packet switching, reduces the complexity of operating
 protocols like PPP and frame relay, provides logical networks and
 traffic segregation for Virtual Private Networks (VPNs), security and
 traffic engineering, enables efficient WAN broadcasting and
 multicasting, and reduces address space requirements. VNS reduces the
 number of routing hops over the WAN by switching packets based on
 labels.
 VNS has been proven in production networks for several years.

Table of Contents

 1       Introduction ............................................   2
 2       What is VNS? ............................................   3
 3       VNS Header  .............................................   5
 4       VNS Label Distribution ..................................   7
 5     Logical Networks (LNs) ....................................   7
 6       VNS Routing .............................................   8
 7       VNS Forwarding ..........................................   9
    7.1   Unicast ................................................   9
    7.2   Multicast ..............................................   9
 8       Traffic Engineering .....................................  10

Jamoussi, et. al. Informational [Page 1] RFC 2340 Nortel's Virtual Network Switching (VNS) May 1998

    8.1   Equal Cost Multipaths ..................................  10
    8.2   Trunk Load Spreading ...................................  10
 9       Class of Service ........................................  11
 10      VNS Migration Strategies ................................  11
 11      Summary .................................................  11
 12      Security Considerations .................................  12
 13      Acknowledgments .........................................  12
 14      Authors' Addresses ......................................  13
 15      Full Copyright Statement ................................  14

1. Introduction

 There are several key problem areas with today's wide area backbone
 networks that carry LAN traffic: scalability, service
 differentiation, redundancy, administration, and traffic containment.
 First, scalability is becoming a major concern because of the rapid
 growth in bandwidth demand and geographical reach. As the size of the
 WAN network grows traditional point-to-point and NBMA topologies or
 network models lose their performance.
 Second, the need to provide several Classes of Service (CoS) has
 never been greater. The days of a single "best effort" service are
 over and service providers demand ways to differentiate the quality
 of the service offered to their clients based on several policies.
 Third, the WAN is often carrying mission-critical traffic and loss of
 service is not acceptable. So far, path redundancy has been addressed
 inefficiently by requiring additional links or VCs.
 Fourth, network operators demand easy and simplified network
 administration. Large NBMA topologies require extensive PVC
 provisioning until SVC  deployment becomes more ubiquitous. For
 Point-to-point models, IP address space may be used inefficiently and
 non-trivial network schemas are required to contain reserved address
 space.
 Finally, proper segregation of traffic is becoming a must. This
 requirement is being addressed today by adding leased lines or VCs
 used to separate traffic flows based on regions or interest or
 protocol.
 Nortel's Virtual Network Switching (VNS) is a technology that
 provides efficient solutions to these challenges.

Jamoussi, et. al. Informational [Page 2] RFC 2340 Nortel's Virtual Network Switching (VNS) May 1998

 Section 2 provides an overview of VNS. The VNS header is specified in
 Section 3. Section 4 describes the VNS label distribution mechanism.
 Section 5 defines how a VNS network can be partitioned into Logical
 Networks (LN). Section 6 outlines VNS routing. Section 7 defines both
 unicast and multicast forwarding. Section 8 describes the mechanisms
 used to engineer the traffic. Section 9 defines the COS based
 switching of VNS. Section 10 provides network migration scenarios
 using VNS. A summary of VNS is provided in Section 11.

2. What is VNS?

 Virtual Network Switching (VNS) is a CoS-sensitive multi-protocol
 label switching architecture that reduces or eliminates the number of
 layer 3 hops over the WAN by switching traffic based on labels.
 VNS makes a network of point to point links  appear to be a single
 LAN (broadcast, multiple access) media.  The network used by a
 particular instance of VNS is called a Logical Network (LN) which is
 described in more detail in Section 5.
 In reference to the ISO Network Layering Model, the Data Link Layer
 is expanded to include VNS network layer. To the ISO Network Layer,
 (e.g., IP), VNS is treated as a Data Link Layer.
  1. ———————–

| Application |

  1. ———————–

| Presentation |

  1. ———————–

| Session |

  1. ———————–

| Transport |

  1. ———————– ————————-

| Network (e.g., IP) | / Network VNS |

  1. —————————- |

| Data Link |————————–

  1. —————————- |

| Physical | \ data link (e.g., ATM) |

  1. ———————– ————————-
             Figure 1. ISO Network Layering Model for VNS
 In a VNS Network, three separate nodal functions are defined.  An
 ingress node, an egress node, and a tandem node. The ingress and
 egress nodes define the boundary between an IP network and the VNS
 network. Therefore, these nodes run both IP routing and VNS routing.
 However, tandem nodes need only run VNS routing.

Jamoussi, et. al. Informational [Page 3] RFC 2340 Nortel's Virtual Network Switching (VNS) May 1998

 A LAN packet is encapsulated in a VNS header as it enters the LN. The
 label in the header is used to switch the packet across the LN. The
 encapsulation header contains the identifier of the last node (or
 egress node) that processes the packet as it traverses the LN. It is
 the first  node (or ingress node) that decides to which egress node
 the packet is sent. All nodes between the ingress and egress nodes
 (known as tandem nodes) decide independently the best packet
 forwarding route to the egress node identified in the packet.
 The network layer protocols view VNS as a shared broadcast media,
 where the speed to reach any node on the media is the same for all
 nodes. VNS ensures that traffic destined to other nodes is forwarded
 optimally. This transparent view of the VNS means that all the
 details of the network (for example, topology and link states) can be
 hidden from the Upper Layer Protocols (e.g. Layer 3 routing
 protocols) and their applications. VNS also ensures that changes to
 topology and link state are hidden.
 The network layer protocol on the ingress node views the network
 layer protocol on the egress node as its logical and directly
 connected neighbor. This is significant because the network layer
 protocols always decide which directly connected neighbor should
 receive a forwarded packet. The details of the actual topology
 supporting the connectionless network are managed entirely by the
 Virtual Network Switching and are hidden from the network layer
 protocols. To the network layer, VNS simply appears to be another
 Data Link Layer (or media), even though VNS is a network layer itself
 running on top of the actual Data Link Layer (for example, ATM
 trunks).
 For the ingress node to choose the egress node that provides the best
 path to the packet's final destination, it must have knowledge of the
 following:
  1. the nodes that can be reached in the network
  2. the topology of the network that is using the VNS services for

transport across the network (but not necessarily the topology

      of the full network)
 This knowledge is obtained through the network layer routing
 mechanisms such as, IP's Open Shortest Path First (OSPF) and Address
 Resolution Protocol (ARP).
 Once the network layer protocol on the ingress node has decided which
 neighbor to transmit the packet to, it is the responsibility of VNS
 forwarding, a part of VNS, to deliver the packet to that node. Once
 the packet arrives at the egress node, the packet is delivered to the
 network layer protocol, which then forwards it to its ultimate

Jamoussi, et. al. Informational [Page 4] RFC 2340 Nortel's Virtual Network Switching (VNS) May 1998

 destination.
 Tandem nodes have no interaction with the network layer protocols.
 They only require knowledge of the  VNS network topology. They make
 their packet forwarding decision on the egress node  identifier and
 LN identifier carried in the VNS header of the packet.

3. VNS Header

 VNS defines a unicast header shown in Figure 2 and a multicast header
 shown in Figure 3.
     3                   2                   1                   0
   1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |      TTL      |      LNN            |x|LS-Key |x|DP | CmnHdr  |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | Protocol Type |         Destination Node Identifier           |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |  COS  |x x x x|         Source Node Identifier                |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                 Network Layer Header (e.g. IP)                |
  /                                                               /
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                          Data                                 |
  /                                                               /
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     Figure 2. Unicast VNS Header
 The unicast header includes the following fields:
  1. Common Header (CmnHdr): The common header identifies the packet to

be a VNS encapsulated packet.

  1. Discard Priority: Indicates the level of congestion at which the

packet should be discarded. The value of this field is assigned on

 the originating node based on policy information (see Section 9).
  1. Load Spreading Key: indicates the stream to which the packet

belongs for the purposes of equal cost multipath and trunk load

 spreading (see Section 8).
  1. LNN: The Logical Network Number defines the logical network the

packet belongs to. This field in is used in conjunction with the

 destination node identifier as the VNS switching label (see Section
 5).

Jamoussi, et. al. Informational [Page 5] RFC 2340 Nortel's Virtual Network Switching (VNS) May 1998

  1. TTL: The Time To Live field is used to detect and discard packets

caught in temporary routing loops.

  1. Destination Node Identifier: This field contains an ID which

uniquely identifies the destination node. This ID is unique to the

 physical network not just the LN. In conjunction with the LNN, this
 forms a global VNS switching label.
  1. Protocol Type: indicates the type of Network layer protocol being

carried in the packet. Examples include IP, IPX, and Bridging. If the

 packet is a multicast packet then this is indicated in this field.
  1. Source Node Identifier: This field contains an ID which uniquely

identifies the source node (ingress node).

  1. CoS: The Class of Service field is used to provide routing class of

service. The COS field also affects the Emission Priority of the

 packet in the scheduler (see Section 9).
  1. Reserved Fields: All the fields marked with "x" are Reserved.
     3                   2                   1                   0
   1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |      TTL      |      LNN            |x|LS-Key |x|DP | CmnHdr  |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | PT = Multicast|         Destination Node Identifier           |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |  COS  |x x x x|         Source Node Identifier                |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | Protocol Type |x x x x x x x x|    Multicast Group            |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                 Network Layer Header (e.g. IP)                |
  /                                                               /
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  /                          Data                                 /
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                    Figure 3. Multicast VNS Header
 The multicast header shown in Figure 3, includes all the fields of
 the unicast header. In addition, the multicast header includes the
 following fields:
  1. Multicast Group: this field is used to identify a sub-group within

the logical network that receives the multicast packets.

Jamoussi, et. al. Informational [Page 6] RFC 2340 Nortel's Virtual Network Switching (VNS) May 1998

  1. Protocol Type: indicates the type of Network layer protocol being

carried in the packet. Examples include IP, IPX, and Bridging.

4. VNS Label Distribution

 Label distribution in VNS is based on a distributed serverless
 topology driven approach. Standard ARP or address gleaning is used to
 distribute and map network layer addresses to VNS addresses.
 A VNS Label is an 6 byte encoding of the LNN and the node ID.  VNS
 Labels are treated as MAC addresses by the network layer.  This means
 that labels are distributed by the same means network layers use to
 distribute MAC addresses.  Thus, VNS leverages existing L2/L3 mapping
 techniques and doesn't require a separate Label Distribution
 Protocol.

5. Logical Networks (LNs)

 A logical network consists of a subset of the nodes in a network
 together with a subset of the trunking facilities that link those
 nodes. Logical networks partition the network into subnetworks that
 serve a subset of the overall topology.
 Each of the logical networks supported on any given node has a
 separate routing and forwarding table (built by VNS). Therefore,
 routing decisions are based on the resources available to the logical
 network, not the entire network.
 Each instance of VNS will discover all the trunks which are connected
 to neighbors which support a matching LNN.  This provides a huge
 administrative saving, since VNS provisioning is on a per-node basis,
 not on a per-link basis.  VNS provisioning requires only a unique
 node ID and an LNN.  Discovery of which trunks support which LNNs is
 done at run time, relieving administrative effort, and allowing the
 LN to dynamically adapt to topology changes.
 Multiple Logical Networks provide the following benefits to the
 network system:
  1. Logical networks allow service providers to service multiple

private networks or (Virtual Private Internets) easily over one

    network.
  1. Logical networks can be used to limit the impact of one network

layer protocol on the others. This is particularly true for

    protocols that broadcast or multicast a large percentage of either
    their control or data packets.  This increases the effective
    bandwidth of the trunks and allows the overall network to scale

Jamoussi, et. al. Informational [Page 7] RFC 2340 Nortel's Virtual Network Switching (VNS) May 1998

    better.
  1. Logical networks allow for the configuration of the network to

meet individual community of interest and geographical

    subnetworking needs.
  1. Routing control traffic has significance only in the local

subnetwork that is isolated to that subnetwork.

  1. Logical networks allow different instances of the same protocol

to share trunk facilities.

6. VNS Routing

 VNS routing is a link state routing system which uses many concepts
 similar to OSPF and PNNI. One of the most significant departures from
 the others is its ability to calculate shortest path trees for
 routing unicast traffic and spanning trees for routing multicast
 traffic within a Logical Network.
 There is only one type of interface that VNS routing supports and
 this is known as a VNS link. A link is a set of trunks that join two
 VNS neighbor nodes. Each node in a VNS network maintains information
 about the state of locally attached links. This information is
 flooded throughout the network whenever there is a significant change
 to the link's state or attributes (i.e. up/down, speed change,
 available bandwidth change).
 Each node stores and forwards the link state information received
 from all other nodes. This allows each node to have the same view of
 all of the nodes in the network together with all of their link state
 information. This data is used to compute both the shortest path to
 reach each node in the Logical Network and a spanning tree for the
 Logical Network.
 Logical networks are not bound to a particular trunk or link. They
 are configured on a node. By default, a link will support a specific
 logical network if the two nodes which it connects both are
 configured to support the logical network number. This provides a
 significant savings in operations over having to configure logical
 networks on links or trunks.
 When a link first comes into service, a protocol is run which allows
 the two neighboring nodes to exchange information about the logical
 networks they support. This allows the two nodes to determine if the
 links are to be considered as a locally attached link for a logical
 network.

Jamoussi, et. al. Informational [Page 8] RFC 2340 Nortel's Virtual Network Switching (VNS) May 1998

7. VNS Forwarding

 VNS supports two types of forwarding: unicasting and multicasting. In
 the first type, the data packet arrives on the ingress node and
 unicasting forwards the data packet to a single destination (egress
 node). In the second type, the data packet arrives on the ingress
 node and multicasting forwards the data packet to all other nodes in
 the logical network.

7.1 Unicast

 When a packet first enters the  LAN internetwork, the network layer
 routing protocol determines the next hop of the best route for the
 packet to reach its final destination. If the best route is through a
 VNS Logical Network, the network layer routing protocol relies on VNS
 forwarding to get the packet to the egress  node. A VNS packet header
 containing the node ID (the unique ID assigned  to each  node) of the
 egress node is added to the front of the packet and VNS forwarding is
 invoked to deliver the packet. The network layer routing protocol
 learns the egress node ID through an Address Resolution Protocol
 (ARP) for IP and Source Address learning for bridging.
 As the packet traverses the LN, routing decisions are made to
 determine the next hop in the route to reach the destination node ID
 specified in the VNS header. A forwarding table is built on each node
 that assists in making the routing decision.
 Each VNS instance on each  node builds and maintains a forwarding
 table for its LN. Each forwarding table has an entry for every  node
 that is a member of the logical network.

7.2 Multicast

 In addition to the unicast forwarding function, VNS also supports a
 multicast forwarding service for traffic within an LN at the VNS
 layer. Multicast packets are delivered to all nodes supporting the
 logical network to which the multicast packet belongs. The packets
 are sent along the branches of a spanning tree that is built by each
 node supporting the logical network and is based on a common root
 node (so that each node's view of the tree is the same as other
 nodes). In other words, multicast packets are sent intelligently,
 consuming a minimum of network bandwidth. If the network topology is
 stable, each node receives each multicast packet only once.
 Multicast packets received at any node are not acknowledged. They are
 simply forwarded to the specified network layer interface and sent to
 any other neighbor nodes on the spanning tree.

Jamoussi, et. al. Informational [Page 9] RFC 2340 Nortel's Virtual Network Switching (VNS) May 1998

8. Traffic Engineering

 VNS forwarding supports two types of traffic engineering mechanisms:
 equal cost multipaths and trunk load spreading.
 Equal cost multipaths allows different streams (unique network layer
 source and destination address pairings) to be load spread between
 multiple relatively equal cost paths, through the Logical Network to
 the egress node.
 Trunk load spreading between two neighbors can take place when
 multiple VNS  trunks are defined between neighbors. Again, the load
 spreading is based on network layer streams.

8.1 Equal Cost Multipaths

 From any point in a logical network, there may be multiple paths to
 reach a specific egress node. If VNS routing determines that more
 than one of these paths are of equal cost, VNS packets will be load
 spread between two of them.
 Equal cost multipath forwarding is supported not only on ingress
 nodes but on tandem nodes as well. Each packet on an ingress node is
 tagged with an equal cost multipath key. This key is acted upon at
 the ingress node and stored in the VNS header to be used on tandem
 nodes.
 The equal cost multipath key is calculated by running an algorithm
 over the source and destination network layer addresses. This means
 that, in a stable network, any given stream will always take the same
 path through a Logical Network avoiding the problems that misordering
 would otherwise cause.

8.2 Trunk Load Spreading Between Neighbors

 VNS allows multiple trunks to be configured between neighboring VNS
 nodes. VNS routing considers the aggregate bandwidth of those trunks
 to determine the metric between the nodes. Also, VNS load spreads its
 traffic amongst those trunks.
 As is the case with equal cost multipaths, the trunk load spreading
 key is calculated on the ingress node from an algorithm run over the
 source and destination network layer addresses. The key is then
 stored in the VNS header to be used on all tandem nodes through the
 Logical Network.

Jamoussi, et. al. Informational [Page 10] RFC 2340 Nortel's Virtual Network Switching (VNS) May 1998

9. Class of Service

 At the ingress to a VNS Network, packets are classified according to
 the Class of Service (Cos) policy settings. The CoS differentiation
 is achieved through different  Emission and Discard priorities. The
 semantics of the classification is carried in the VNS label (DP and
 COS Fields described in Section 3) to be used at the ingress node as
 well as all tandem points in the VNS network to affect queuing and
 scheduling decisions.

10. VNS Migration Strategies

 VNS supports several upper layer protocols such as IP, IPX, and
 Bridging. Therefore, it is a multiprotocol label switching
 architecture. In addition, VNS  is not tied to a particular L2
 technology. It runs on cell (e.g., ATM) trunks, frame trunks, or a
 mixture of both.
 VNS can be gradually introduced in a network. It can be implemented
 between switching elements interconnected by point to point links.
 Each of the switching nodes can run layer 3 routing simultaneously
 with packet switching. VNS also allows for the interconnection of VNS
 clouds through an ATM VC.
 Since VNS can run on a mixture of Frame and Cell trunks, it allows
 for the graceful migration of the frame links to ATM without
 requiring a complete immediate overhaul.

11. Summary

 VNS addresses scalability problems in several ways:
    1. By a generally distributed design which doesn't
       require a Label Distribution Protocol, or servers of any kind.
    2. By providing an efficient, distributed multicast mechanism.
    3. By allowing administrators to control the size of a
       Logical Network, limiting traffic to a subset of the physical
       topology.
    4. By reducing layer 3 address space/subnet requirements in the
       WAN which reduces the routing table size.
 VNS provides redundancy transparent to the network layer protocol by
 managing the network of trunks independently of the network layer.
 VNS will automatically discover any topology changes and re-route
 traffic accordingly.

Jamoussi, et. al. Informational [Page 11] RFC 2340 Nortel's Virtual Network Switching (VNS) May 1998

 VNS eases network administration by dynamically keeping track of
 which trunks are available for each LNN.  Network administrators
 don't have to configure VNS or network layer addresses on a per link
 basis.  Network layer addresses only have to be assigned on a per
 Logical Network basis.  For nodes which will only be tandem VNS
 nodes, network layer addresses aren't required at all.
 Since VNS traffic is constrained within an LNN, administrators have
 control of where VNS traffic is allowed to flow.
 Finally, VNS supports switching of several Upper Layer Protocols and
 supports  several media (cell and Frame) or a mixture thereof.
 Switching in the core of the WAN removes the need for routers and
 improves the performance due to a reduction in the  number of fields
 that need to processed.

12. Security Considerations

 Logical networks provide a means of restricting traffic flow for
 security purposes. VNS also relies on the inherent security of the L2
 media such as an ATM Virtual Circuit.

13. Acknowledgments

 The authors would like to acknowledge the valuable comments of Terry
 Boland, Pierre Cousineau, Robert Eros, Robert Tomkins, and John
 Whatman.

Jamoussi, et. al. Informational [Page 12] RFC 2340 Nortel's Virtual Network Switching (VNS) May 1998

14. Authors' Addresses

 Bilel Jamoussi
 Nortel (Northern Telecom), Ltd.
 PO Box 3511 Station C
 Ottawa ON K1Y 4H7
 Canada
 EMail: jamoussi@Nortel.ca
 Dwight Jamieson
 Nortel (Northern Telecom), Ltd.
 PO Box 3511 Station C
 Ottawa ON K1Y 4H7
 Canada
 EMail: djamies@Nortel.ca
 Dan Williston
 Nortel (Northern Telecom), Ltd.
 PO Box 3511 Station C
 Ottawa ON K1Y 4H7
 Canada
 EMail: danwil@Nortel.ca
 Stephen Gabe
 Nortel (Northern Telecom), Ltd.
 PO Box 3511 Station C
 Ottawa ON K1Y 4H7
 Canada
 EMail: spgabe@Nortel.ca

Jamoussi, et. al. Informational [Page 13] RFC 2340 Nortel's Virtual Network Switching (VNS) May 1998

15. Full Copyright Statement

 Copyright (C) The Internet Society (1998).  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
 and distributed, in whole or in part, without restriction of any
 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
 copyrights defined in the Internet Standards process must be
 followed, or as required to translate it into languages other than
 English.
 The limited permissions granted above are perpetual and will not be
 revoked by the Internet Society or its successors or assigns.
 This document and the information contained herein is provided on an
 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Jamoussi, et. al. Informational [Page 14]

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