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Versions: 00 01 02 03

Network Working Group                                            R. Bush
Internet-Draft                                              Arrcus & IIJ
Intended status: Standards Track                              R. Austein
Expires: May 10, 2019                                           K. Patel
                                                                  Arrcus
                                                        November 6, 2018


                        Link State Over Ethernet
                        draft-ymbk-lsvr-lsoe-03

Abstract

   Used in Massive Data Centers (MDCs), BGP-SPF and similar protocols
   need link neighbor discovery, link encapsulation data, and Layer 2
   liveness.  The Link State Over Ethernet protocol provides link
   discovery, exchanges supported encapsulations (IPv4, IPv6, ...),
   discovers encapsulation addresses (Layer 3 / MPLS identifiers) over
   raw Ethernet, and provides layer 2 liveness checking.  The interface
   data are pushed directly to a BGP-LS API, obviating the need for
   centralized controller architectures.  This protocol is intended to
   be more widely applicable to other upper layer routing protocols
   which need link discovery and characterisation.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to
   be interpreted as described in [RFC2119] only when they appear in all
   upper case.  They may also appear in lower or mixed case as English
   words, without normative meaning.  See [RFC8174].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 10, 2019.



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Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Background  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Top Level Overview  . . . . . . . . . . . . . . . . . . . . .   5
   5.  Ethernet to Ethernet Protocols  . . . . . . . . . . . . . . .   6
     5.1.  Inter-Link Ether Protocol Overview  . . . . . . . . . . .   6
   6.  Transport Layer . . . . . . . . . . . . . . . . . . . . . . .   8
   7.  The Checksum  . . . . . . . . . . . . . . . . . . . . . . . .   8
   8.  TLV PDUs  . . . . . . . . . . . . . . . . . . . . . . . . . .  10
   9.  HELLO . . . . . . . . . . . . . . . . . . . . . . . . . . . .  10
   10. OPEN  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  11
   11. ACK . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  13
     11.1.  Retransmission . . . . . . . . . . . . . . . . . . . . .  13
   12. The Encapsulations  . . . . . . . . . . . . . . . . . . . . .  13
     12.1.  The Encapsulation PDU Skeleton . . . . . . . . . . . . .  14
     12.2.  Prim/Loop Flags  . . . . . . . . . . . . . . . . . . . .  15
     12.3.  IPv4 Encapsulation . . . . . . . . . . . . . . . . . . .  15
     12.4.  IPv6 Encapsulation . . . . . . . . . . . . . . . . . . .  16
     12.5.  MPLS Label List  . . . . . . . . . . . . . . . . . . . .  16
     12.6.  MPLS IPv4 Encapsulation  . . . . . . . . . . . . . . . .  16
     12.7.  MPLS IPv6 Encapsulation  . . . . . . . . . . . . . . . .  17
   13. KEEPALIVE - Layer 2 Liveness  . . . . . . . . . . . . . . . .  18
   14. Layers 2.5 and 3 Liveness . . . . . . . . . . . . . . . . . .  19
   15. The North/South Protocol  . . . . . . . . . . . . . . . . . .  19
     15.1.  Use BGP-LS as Much as Possible . . . . . . . . . . . . .  19
     15.2.  Extensions to BGP-LS . . . . . . . . . . . . . . . . . .  20
   16. Discussion  . . . . . . . . . . . . . . . . . . . . . . . . .  20
     16.1.  HELLO Discussion . . . . . . . . . . . . . . . . . . . .  20
     16.2.  HELLO versus KEEPALIVE . . . . . . . . . . . . . . . . .  20
   17. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . .  21
   18. Security Considerations . . . . . . . . . . . . . . . . . . .  21



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   19. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  21
   20. IEEE Considerations . . . . . . . . . . . . . . . . . . . . .  22
   21. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  22
   22. References  . . . . . . . . . . . . . . . . . . . . . . . . .  22
     22.1.  Normative References . . . . . . . . . . . . . . . . . .  22
     22.2.  Informative References . . . . . . . . . . . . . . . . .  23
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  24

1.  Introduction

   The Massive Data Center (MDC) environment presents unusual problems
   of scale, e.g.  O(10,000) devices, while its homogeneity presents
   opportunities for simple approaches.  Approaches such as Jupiter
   Rising [JUPITER] use a central controller to deal with scaling, while
   BGP-SPF [I-D.ietf-lsvr-bgp-spf] provides massive scale-out without
   centralization using a tried and tested scalable distributed control
   plane, offering a scalable routing solution in Clos and similar
   environments.  But BGP-SPF and similar higher level device-spanning
   protocols need link state and addressing data from the network to
   build the routing topology.  LLDP has scaling issues, e.g. in
   extending a message beyond 1,500 bytes.

   Link State Over Ethernet (LSOE) provides brutally simple mechanisms
   for devices to

   o  Discover each other's Layer 2 (MAC) Addresses,

   o  Run Layer 2 keep-alive messages for liveness continuity,

   o  Discover each other's unique IDs (ASN, RouterID, ...),

   o  Discover mutually supported encapsulations, e.g.  IP/MPLS,

   o  Discover Layer 3 and/or MPLS addressing of interfaces of the link
      encapsulations,

   o  Enable layer 3 link liveness such as BFD, and finally

   o  Present these data, using a very restricted profile of a BGP-LS
      [RFC7752] API, to BGP-SPF which computes the topology and builds
      routing and forwarding tables.

   This protocol may be more widely applicable to a range of routing and
   similar protocols which need link discovery and characterisation.







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2.  Terminology

   Even though it concentrates on the Ethernet layer, this document
   relies heavily on routing terminology.  The following are some
   possibly confusing terms:

   Association:  An established, vis OPEN PDUs, session between two LSOE
              capable devices,
   ASN:       Autonomous System Number [RFC4271], a BGP identifier for
              an originator of Layer 3 routes, particularly BGP
              announcements.
   BGP-LS:    A mechanism by which link-state and TE information can be
              collected from networks and shared with external
              components using the BGP routing protocol.  See [RFC7752].
   BGP-SPF    A hybrid protocol using BGP transport but a Dijkstra SPF
              decision process.  See [I-D.ietf-lsvr-bgp-spf].
   Clos:      A hierarchic subset of a crossbar switch topology commonly
              used in data centers.
   Datagram:  The LSOE content of a single Ethernet frame.  A full LSOE
              PDU may be packaged in multiple Datagrams.
   Encapsulation:  Address Family Indicator and Subsequent Address
              Family Indicator (AFI/SAFI).  I.e. classes of addresses
              such as IPv4, IPv6, MPLS, ...
   Frame:     An Ethernet Layer 2 packet.
   MAC Address:  Media Access Control Address, essentially an Ethernet
              address, six octets.
   MDC:       Massive Data Center, commonly thousands of TORs.
   PDU:       Protocol Data Unit, an LSOE application layer message.  A
              PDU may need to be broken into multiple Datagrams to make
              it through MTU or other restrictions.
   RouterID:  An 32-bit identifier unique in the current routing domain,
              see [RFC4271] updated by [RFC6286].
   SPF:       Shortest Path First, an algorithm for finding the shortest
              paths between nodes in a graph; AKA Dijkstra's algorithm.
   TOR:       Top Of Rack switch, aggregates the servers in a rack and
              connects to aggregation layers of the Clos tree, AKA the
              Clos spine.
   ZTP:       Zero Touch Provisioning gives devices initial addresses,
              credentials, etc. on boot/restart.

3.  Background

   LSOE assumes a datacenter scale and topology, but can accommodate
   richer topologies which contain potential cycles.

   While LSOE is designed for the MDC, there are no inherent reasons it
   could not run on a WAN; though, as it is simply a discovery protocol,
   it is not clear that this would be useful.  The authentication and



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   authorisation needed to run safely on the WAN are not provided in
   detail in this version of the protocol, although future versions/
   extensions could expend on them.

   LSOE assumes a new IEEE assigned EtherType (TBD).

4.  Top Level Overview

   o  Devices discover each other on Ethernet links

   o  MAC addresses and Link State are exchanged over Ethernet

   o  Layer 2 Liveness Checks are begun

   o  Encapsulation data are exchanged and IP-Level Liveness Checks done

   o  A BGP-like protocol is assumed to use these data to discover and
      build a topology database

   +-------------------+   +-------------------+   +-------------------+
   |      Device       |   |      Device       |   |      Device       |
   |                   |   |                   |   |                   |
   |+-----------------+|   |+-----------------+|   |+-----------------+|
   ||                 ||   ||                 ||   ||                 ||
   ||     BGP-SPF     <+---+>     BGP-SPF     <+---+>     BGP-SPF     ||
   ||                 ||   ||                 ||   ||                 ||
   |+--------^--------+|   |+--------^--------+|   |+--------^--------+|
   |         |         |   |         |         |   |         |         |
   |         |         |   |         |         |   |         |         |
   |+--------+--------+|   |+--------+--------+|   |+--------+--------+|
   ||   L2 Liveness   ||   ||   L2 Liveness   ||   ||   L2 Liveness   ||
   ||  Encapsulations ||   ||  Encapsulations ||   ||  Encapsulations ||
   ||    Addresses    ||   ||    Addresses    ||   ||    Addresses    ||
   |+--------^--------+|   |+--------^--------+|   |+--------^--------+|
   |         |         |   |         |         |   |         |         |
   |         |         |   |         |         |   |         |         |
   |+--------v--------+|   |+--------v--------+|   |+--------v--------+|
   ||                 ||   ||                 ||   ||                 ||
   ||   Ether PDUs    <+---+>   Ether PDUs    <+---+>   Ether PDUs    ||
   ||                 ||   ||                 ||   ||                 ||
   |+-----------------+|   |+-----------------+|   |+-----------------+|
   +-------------------+   +-------------------+   +-------------------+

   There are two protocols, the Ethernet discovery and the interface to
   the upper level BGP-like protocol:






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   o  Layer 2 Ethernet protocols are used to exchange Layer 2 data, i.e.
      MAC addresses, and layer 2.5 and 3 identifiers (not payloads),
      i.e. ASNs, Encapsulations, and interface addresses.

   o  A Link Layer to BGP API presents these data up the stack to a BGP
      protocol or an other device-spanning upper layer protocol,
      presenting them using the BGP-LS BGP-like data format.

   The upper layer BGP family routing protocols cross all the devices,
   though they are not part of these LSOE protocols.

   To simplify this document, Layer 2 Ethernet framing is not shown.

5.  Ethernet to Ethernet Protocols

   Two devices discover each other and their respective MAC addresses by
   sending multicast HELLO PDUs (Section 9).  To allow discovery of new
   devices coming up on a multi-link topology, devices send periodic
   HELLOs forever, see Section 16.1.

   Once a new device is recognized, both devices attempt to negotiate
   and establish peering by sending unicast OPEN PDUs (Section 10).  In
   an established peering, Encapsulations (Section 12) may be announced
   and modified.  When two devices on a link have compatible
   Encapsulations and addresses, i.e. the same AFI/SAFI and the same
   subnet, the link is announced via the BGP-LS API.

5.1.  Inter-Link Ether Protocol Overview

   The HELLO, Section 9, is a priming message.  It is an Ethernet
   multicast frame with a small LSOE PDU with the simple goal of
   discovering the Ethernet MAC address(es) of devices reachable via an
   interface.

   The HELLO and OPEN, Section 10, PDUs, which are used to discover and
   exchange MAC address and IDs, are mandatory; other PDUs are optional;
   though at least one encapsulation MUST be agreed at some point.

   The following is a ladder-style sketch of the Ethernet protocol
   exchanges:

   |             HELLO           | MAC Address discovery
   |---------------------------->|
   |             HELLO           | Mandatory
   |<----------------------------|
   |                             |
   |                             |
   |             OPEN            | MACs, IDs, and Capabilities



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   |---------------------------->|
   |             OPEN            | Mandatory
   |<----------------------------|
   |                             |
   |                             |
   |   Interface IPv4 Addresses  | Interface IPv4 Addresses
   |---------------------------->| Optional
   |            ACK              |
   |<----------------------------|
   |                             |
   |   Interface IPv4 Addresses  |
   |<----------------------------|
   |            ACK              |
   |---------------------------->|
   |                             |
   |                             |
   |   Interface IPv6 Addresses  | Interface IPv6 Addresses
   |---------------------------->| Optional
   |            ACK              |
   |<----------------------------|
   |                             |
   |   Interface IPv6 Addresses  |
   |<----------------------------|
   |            ACK              |
   |---------------------------->|
   |                             |
   |                             |
   |   Interface MPLSv4 Labels   | Interface MPLSv4 Labels
   |---------------------------->| Optional
   |            ACK              |
   |<----------------------------|
   |                             |
   |   Interface MPLSv4 Labels   | Interface MPLSv4 Labels
   |<----------------------------| Optional
   |            ACK              |
   |---------------------------->|
   |                             |
   |                             |
   |   Interface MPLSv6 Labels   | Interface MPLSv6 Labels
   |---------------------------->| Optional
   |            ACK              |
   |<----------------------------|
   |                             |
   |   Interface MPLSv6 Labels   | Interface MPLSv6 Labels
   |<----------------------------| Optional
   |            ACK              |
   |---------------------------->|
   |                             |



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   |                             |
   |        LSOE KEEPALIVE       | Layer 2 Liveness
   |---------------------------->| Optional
   |        LSOE KEEPALIVE       |
   |<----------------------------|

6.  Transport Layer

   LSOE PDU are carried by a simple transport layer which allows long
   PDUs to occupy multiple Ethernet frames.  The LSOE data in each frame
   is referred to as a Datagram.

   The LSOE Transport Layer encapsulates each Datagram using a common
   transport header.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Version   |L|Datagram Number|        Datagram Length        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                            Checksum                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The fields of the LSOE Transport Header are as follows:

   Version:  Version number of the protocol, currently 0.  Values other
      than 0 are treated as failure.

   Datagram Number:  0..255, a monotonically increasing value, modulo
      256, see [RFC1982].

   L: A bit that set to 1 if this Datagram is the last Datagram of the
      PDU.  For a PDU which fits in only one Datagram, it is set to one.

   PDU Length:  Total number of octets in the Datagram including all
      payloads and fields.

   Checksum:  A 32 bit hash over the Datagram to detect bit flips, see
      Section 7.

7.  The Checksum

   There is a reason conservative folk use a checksum in UDP.  And as
   many operators stretch to jumbo frames (over 1,500 octets) longer
   checksums are the conservative approach.

   For the purpose of computing a checksum, the checksum field itself is
   assumed to be zero.



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   Sum up 32-bit unsigned ints in a 64-bit long, then take the high-
   order section, shift it right, rotate, add it in, repeat until zero.


   #include <stddef.h>
   #include <stdint.h>

   /* The F table from Skipjack, and it would work for the S-Box. */
   static const uint8_t sbox[256] = {
   0xa3,0xd7,0x09,0x83,0xf8,0x48,0xf6,0xf4,0xb3,0x21,0x15,0x78,
   0x99,0xb1,0xaf,0xf9,0xe7,0x2d,0x4d,0x8a,0xce,0x4c,0xca,0x2e,
   0x52,0x95,0xd9,0x1e,0x4e,0x38,0x44,0x28,0x0a,0xdf,0x02,0xa0,
   0x17,0xf1,0x60,0x68,0x12,0xb7,0x7a,0xc3,0xe9,0xfa,0x3d,0x53,
   0x96,0x84,0x6b,0xba,0xf2,0x63,0x9a,0x19,0x7c,0xae,0xe5,0xf5,
   0xf7,0x16,0x6a,0xa2,0x39,0xb6,0x7b,0x0f,0xc1,0x93,0x81,0x1b,
   0xee,0xb4,0x1a,0xea,0xd0,0x91,0x2f,0xb8,0x55,0xb9,0xda,0x85,
   0x3f,0x41,0xbf,0xe0,0x5a,0x58,0x80,0x5f,0x66,0x0b,0xd8,0x90,
   0x35,0xd5,0xc0,0xa7,0x33,0x06,0x65,0x69,0x45,0x00,0x94,0x56,
   0x6d,0x98,0x9b,0x76,0x97,0xfc,0xb2,0xc2,0xb0,0xfe,0xdb,0x20,
   0xe1,0xeb,0xd6,0xe4,0xdd,0x47,0x4a,0x1d,0x42,0xed,0x9e,0x6e,
   0x49,0x3c,0xcd,0x43,0x27,0xd2,0x07,0xd4,0xde,0xc7,0x67,0x18,
   0x89,0xcb,0x30,0x1f,0x8d,0xc6,0x8f,0xaa,0xc8,0x74,0xdc,0xc9,
   0x5d,0x5c,0x31,0xa4,0x70,0x88,0x61,0x2c,0x9f,0x0d,0x2b,0x87,
   0x50,0x82,0x54,0x64,0x26,0x7d,0x03,0x40,0x34,0x4b,0x1c,0x73,
   0xd1,0xc4,0xfd,0x3b,0xcc,0xfb,0x7f,0xab,0xe6,0x3e,0x5b,0xa5,
   0xad,0x04,0x23,0x9c,0x14,0x51,0x22,0xf0,0x29,0x79,0x71,0x7e,
   0xff,0x8c,0x0e,0xe2,0x0c,0xef,0xbc,0x72,0x75,0x6f,0x37,0xa1,
   0xec,0xd3,0x8e,0x62,0x8b,0x86,0x10,0xe8,0x08,0x77,0x11,0xbe,
   0x92,0x4f,0x24,0xc5,0x32,0x36,0x9d,0xcf,0xf3,0xa6,0xbb,0xac,
   0x5e,0x6c,0xa9,0x13,0x57,0x25,0xb5,0xe3,0xbd,0xa8,0x3a,0x01,
   0x05,0x59,0x2a,0x46
   };

   /* non-normative example C code, constant time even */

   uint32_t sbox_checksum_32(const uint8_t *b, const size_t n)
   {
     uint32_t sum[4] = {0, 0, 0, 0};
     uint64_t result = 0;
     for (size_t i = 0; i < n; i++)
       sum[i & 3] += sbox[*b++];
     for (int i = 0; i < sizeof(sum)/sizeof(*sum); i++)
       result = (result << 8) + sum[i];
     result = (result >> 32) + (result & 0xFFFFFFFF);
     result = (result >> 32) + (result & 0xFFFFFFFF);
     return (uint32_t) result;
   }




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8.  TLV PDUs

   The basic LSOE application layer PDU is a typical TLV (Type Length
   Value) PDU.  It may be broken into multiple Datagrams, see Section 6

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Type     |           PDU Length          |               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               +
   |                           Value ...                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The fields of the basic LSOE header are as follows:

   Type:  An integer differentiating PDU payload types

         0 - HELLO
         1 - OPEN
         2 - KEEPALIVE
         3 - ACK
         4 - IPv4 Announcement
         5 - IPv6 Announcement
         6 - MPLS IPv4 Announcement
         7 - MPLS IPv6 Announcement
         8-255 Reserved

   PDU Length:  Total number of octets in the PDU including all payloads
      and fields

   Value:  Any application layer content of the LSOE PDU beyond the
      type.

9.  HELLO

   The HELLO PDU is unique in that it is a multicast Ethernet frame.  It
   solicits response(s) from other device(s) on the link.  See
   Section 16.1 for why multicast is used.

   All other LSOE PDUs are unicast Ethernet frames, as the peer's MAC
   Address is known after the HELLO exchange.

   When an interface is turned up on a device, it SHOULD issue a HELLO
   periodically.  The interval is set by configuration.







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   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Type = 0   |         PDU Length = 9        |               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               +
   |                         MyMAC Address                         |
   +               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               |
   +-+-+-+-+-+-+-+-+

   If more than one device responds, one adjacency is formed for each
   unique (MAC address) response.  LSOE treats the adjacencies as
   separate links.

   When a HELLO is received from a MAC address where there is no
   established LSOE adjacency, the receiver SHOULD respond with an OPEN
   PDU.  The two devices establish an LSOE adjacency by exchanging OPEN
   PDUs.

   The PDU Length is the octet count of the entire PDU, including the
   Type, the Datagram Length field itself, and the MyMAC Address
   payload.

   A particular MAC address SHOULD arrive on frames from only one
   interface.

10.  OPEN

   Each device has learned the other's MAC address from the HELLO
   exchange, see Section 9.  Therefore the OPEN and subsequent PDUs are
   unicast, as opposed to the HELLO's multicast, Ethernet frames.




















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    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Type = 1   |           PDU Length          |               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               +
   |                                                               |
   +                                                               +
   |                            Local ID                           |
   +               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               |                                               |
   +-+-+-+-+-+-+-+-+                                               +
   |                      Remote ID (or Zero)                      |
   +                                               +-+-+-+-+-+-+-+-+
   |                                               |   AttrCount   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               Attribute List ...              |  Auth Length  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      ...      |            Authentication Data ...            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   An ID can be an ASN with high order bits zero, a classic RouterID
   with high order bits zero, a catenation of the two, a 80-bit ISO
   System-ID, or any other identifier unique to a single device in the
   current routing space.  IDs are big-endian.

   When the local device sends an OPEN without knowing the remote
   device's ID, the Remote ID MUST be zero.  The Local ID MUST NOT be
   zero.

   AttrCount is the number of attributes in the Attribute List.
   Attributes are single octets whose semantics are user-defined.

   A node may have zero or more user-defined attributes, e.g. spine,
   leaf, backbone, route reflector, arabica, ...

   Attribute syntax and semantics are local to an operator or
   datacenter; hence there is no global registry.  Nodes exchange their
   attributes only in the OPEN PDU.

   Auth Length is a 16-bit field denoting the length in octets of the
   Authentication Data, not including the Auth Length itself.  If there
   are no Authentication Data, the Auth Length MUST BE zero.

   The Authentication Data are specific to the operational environment.
   A failure to authenticate is a failure to start the LSOE association,
   and HELLOs MUST BE restarted.





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   Once two devices know each other's MAC addresses, and have ACKed
   eachother's OPEN PDUs, Layer 2 KEEPALIVEs (see Section 13) SHOULD be
   started to ensure Layer 2 liveness and keep the association semantics
   alive.  The timing and acceptable drop of the KEEPALIVE PDUs SHOULD
   be configured.

   If a properly authenticated OPEN arrives from a device with which the
   receiving device believes it already has an LSOE association (OPENs
   have already been exchanged), the receiver MUST assume that the
   sending device has been reset.  All discovered data MUST BE withdrawn
   via the BGP-LS API and the recipient MUST respond with a new OPEN.

11.  ACK

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Type = 3   |           Length = 4          |    PDU Type   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The ACK acknowledges receipt of an OPEN or an Encapsulation PDU.

   The PDU Type is the Type of the PDU being acknowledged, OPEN or one
   of the Encapsulations.

11.1.  Retransmission

   If a PDU sender expects an ACK, e.g. for an OPEN or an Encapsulation,
   and does not receive the ACK for a configurable time (default one
   second), the sender resends the PDU.  This cycle MAY be repeated a
   configurable number of times (default three) before it is considered
   a failure.  The session is considered closed in case of an ACK
   failure.

12.  The Encapsulations

   Once the devices know each other's MAC addresses, know each other's
   upper layer identities, have means to ensure link state, etc., the
   LSOE 'association' is considered established, and the devices SHOULD
   announce their interface encapsulation, addresses, (and labels).

   The Encapsulation types the peers exchange may be IPv4 Announcement
   (Section 12.3), IPv6 Announcement (Section 12.4), MPLS IPv4
   Announcement (Section 12.6), MPLS IPv6 Announcement (Section 12.7),
   and/or possibly others not defined here.

   The sender of an Encapsulation PDU MUST NOT assume that the peer is
   capable of the same Encapsulation Type.  An ACK (Section 11) merely



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   acknowledges receipt.  Only if both peers have sent the same
   Encapsulation Type is it safe to assume that they are compatible for
   that type.

   Further, to consider a link of a type to formally be established so
   that it may be pushed up to upper layer protocols, the addressing for
   the type must be compatible, i.e. on the same IPvX subnet.

12.1.  The Encapsulation PDU Skeleton

   The header for all encapsulation PDUs is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Type     |           PDU Length          |     Count     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      ...      |             Encapsulation List...             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The 16-bit Count is the number of Encapsulations in the Encapsulation
   list.

   If the length of an Encapsulation PDU exceeds the Datagram size limit
   on media, the PDU is broken into multiple Datagrams.  See Section 8.

   The Receiver MUST acknowledge the Encapsulation PDU with a Type=3,
   ACK PDU (Section 11) with the Encapsulation Type being that of the
   encapsulation being announced, see Section 11.

   If the Sender does not receive an ACK in one second, they SHOULD
   retransmit.  After a user configurable number of failures, the LSOE
   association should be considered dead and the OPEN process SHOULD be
   restarted.

   An Encapsulation PDU describes zero or more addresses of the
   encapsulation type.

   An Encapsulation PDU of Type T replaces all previous encapsulations
   of Type T.

   To remove all encapsulations of Type T, the sender uses a Count of
   zero.

   If an interface has multiple addresses for an encapsulation type, one
   address SHOULD be marked as primary, see Section 12.2.





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   If a loopback address needs to be exposed, e.g. for iBGP peering,
   then it should be marked as such, see Section 12.2.

   If a sender has multiple links on the same interface, separate data,
   ACKs, etc. must be kept for each peer.

   Over time, multiple Encapsulation PDUs may be sent for an interface
   as configuration changes.

12.2.  Prim/Loop Flags

    0               1               2               3    ...       7
   +---------------+---------------+---------------+---------------+
   |  Primary      |   Loopback    |  Reserved ... |               |
   +---------------+---------------+---------------+---------------+

   Each Encapsulation interface address MAY be marked as a primary
   address, and/or a loopback, in which case the respective bit is set
   to one.

   Only one address MAY be marked as primary for an encapsulation type.

12.3.  IPv4 Encapsulation

   The IPv4 Encapsulation describes a device's ability to exchange IPv4
   packets on one or more subnets.  It does so by stating the
   interface's address and the prefix length.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Type = 4   |           PDU Length          |     Count     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      ...      | PrimLoop Flags|          IPv4 Address         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               |   PrefixLen   | PrimLoop Flags|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          IPv4 Address                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   PrefixLen   |                    more ...                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The 16-bit Count is the number of IPv4 Encapsulations.








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12.4.  IPv6 Encapsulation

   The IPv6 Encapsulation describes a device's ability to exchange IPv6
   packets on one or more subnets.  It does so by stating the
   interface's address and the prefix length.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Type = 5   |           PDU Length          |     Count     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      ...      | PrimLoop Flags|                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   |                                                               |
   +                                                               +
   |                                                               |
   +                                                               +
   |                          IPv6 Address                         |
   +                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               |   PrefixLen   |    more ...   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The 16-bit Count is the number of IPv6 Encapsulations.

12.5.  MPLS Label List

   As an MPLS enabled interface may have a label stack, see [RFC3032], a
   variable length list of labels is needed.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Label Count  |                 Label                 | Exp |S|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Label                 | Exp |S|    more ...   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   A Label Count of zero is an implicit withdraw of all labels for that
   prefix on that interface.

12.6.  MPLS IPv4 Encapsulation

   The MPLS IPv4 Encapsulation describes a device's ability to exchange
   labeled IPv4 packets on one or more subnets.  It does so by stating
   the interface's address and the prefix length.






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    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Type = 6   |           PDU Length          |     Count     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      ...      | PrimLoop Flags|      MPLS Label List ...      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              ...              |          IPv4 Address         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              ...              |   PrefixLen   | PrimLoop Flags|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      MPLS Label List ...                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          IPv4 Address                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Prefix Len  |                    more ...                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The 16-bit Count is the number of MPLSv6 Encapsulations.

12.7.  MPLS IPv6 Encapsulation

   The MPLS IPv6 Encapsulation describes a device's ability to exchange
   labeled IPv6 packets on one or more subnets.  It does so by stating
   the interface's address and the prefix length.


























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    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Type = 7   |           PDU Length          |     Count     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      ...      | PrimLoop Flags|      MPLS Label List ...      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              ...              |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   |                                                               |
   +                                                               +
   |                                                               |
   +                                                               +
   |                          IPv6 Address                         |
   +                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               |   Prefix Len  | PrimLoop Flags|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      MPLS Label List ...                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                                                               +
   |                                                               |
   +                          IPv6 Address                         +
   |                                                               |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Prefix Len  |                    more ...                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The 16-bit Count is the number of MPLSv6 Encapsulations.

13.  KEEPALIVE - Layer 2 Liveness

   LSOE devices MUST beacon occasional Layer 2 KEEPALIVE PDUs to ensure
   association continuity.

   They SHOULD be beaconed at a configured frequency.  One per second is
   the default.  Layer 3 liveness, such as BFD, will likely be more
   aggressive.

   If a KEEPALIVE is not received from a peer with which a receiver has
   an open session for a configurable time (default one minute), the
   session SHOULD BE presumed closed.  The devices MAY keep
   configuration state until a new session is established and new
   Encapsulation PDUs are received.






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    0                   1                   2
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Type = 2   |           Length = 3          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

14.  Layers 2.5 and 3 Liveness

   Ethernet liveness is continuously tested by KEEPALIVE PDUs, see
   Section 13.  As layer 2.5 or layer 3 connectivity could still break,
   liveness above layer 2 SHOULD be frequently tested using BFD
   ([RFC5880]) or a similar technique.

   This protocol assumes that one or more Encapsulation addresses will
   be used to ping, BFD, or whatever the operator configures.

15.  The North/South Protocol

   Thus far, a one-hop point-to-point link discovery protocol has been
   defined.

   The nodes know the unique node identifiers (ASNs, RouterIDs, ...) and
   Encapsulations on each link interface.

   Full topology discovery is not appropriate at the Ethernet layer, so
   Dijkstra a la IS-IS etc. is assumed to be done by higher level
   protocols.

   Therefore the node identifiers, link Encapsulations, and state
   changes are pushed North via a small subset of the BGP-LS API.  The
   upper layer routing protocol(s), e.g.  BGP-SPF, learn and maintain
   the topology, run Dijkstra, and build the routing database(s).

   For example, if a neighbor's IPv4 Encapsulation address changes, the
   devices seeing the change push that change Northbound.

15.1.  Use BGP-LS as Much as Possible

   BGP-LS [RFC7752] defines BGP-like Datagrams describing link state
   (links, nodes, link prefixes, and many other things), and a new BGP
   path attribute providing Northbound transport, all of which can be
   ingested by upper layer protocols such as BGP-SPF; see Section 4 of
   [I-D.ietf-lsvr-bgp-spf].

   For IPv4 links, TLVs 259 and 260 are used.  For IPv6 links, TLVs 261
   and 262.  If there are multiple addresses on a link, multiple TLV
   pairs are pushed North, having the same ID pairs.




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15.2.  Extensions to BGP-LS

   The Northbound protocol needs a few minor extensions to BGP-LS.
   Luckily, others have needed the same extensions.

   Similarly to BGP-SPF, the BGP protocol is used in the Protocol-ID
   field specified in table 1 of
   [I-D.ietf-idr-bgpls-segment-routing-epe].  The local and remote node
   descriptors for all NLRI are the ID's described in Section 10.  This
   is equivalent to an adjacency SID or a node SID if the address is a
   loopback address.

   Label Sub-TLVs from [I-D.ietf-idr-bgp-ls-segment-routing-ext]
   Section 2.1.1, are used to associate one or more MPLS Labels with a
   link.

16.  Discussion

   This section explores some trade-offs taken and some considerations.

16.1.  HELLO Discussion

   There is the question of whether to allow an intermediate switch to
   be transparent to discovery.  We consider that an interface on a
   device is a Layer 2 or a Layer 3 interface.  In theory it could be a
   Layer 3 interface with no encapsulation or Layer 3 addressing
   currently configured.

   A device with multiple Layer 2 interfaces, traditionally called a
   switch, may be used to forward frames and therefore packets from
   multiple devices to one interface, I, on an LSOE speaking device.
   Interface I could discover a peer J across the switch.  Later, a
   prospective peer K could come up across the switch.  If I was not
   still sending and listening for HELLOs, the potential peering with K
   could not be discovered.  Therefore, interfaces MUST continue to send
   HELLOs as long as they are turned up.

16.2.  HELLO versus KEEPALIVE

   Both HELLO and KEEPALIVE are periodic.  KEEPALIVE might be eliminated
   in favor of keeping only HELLOs.  But currently KEEPALIVE is unicast,
   has a checksum, is acknowledged, and thus more firmly verifies
   association existence.

   This warrants discussion.






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17.  Open Issues

   VLANs/SVIs/Subinterfaces

18.  Security Considerations

   The protocol as is MUST NOT be used outside a datacenter or similarly
   closed environment due to lack of formal definition of the
   authentication and authorisation mechanism.  These will be worked on
   in a later effort, likely using credentials configured using ZTP or
   similar configuration automation.

   Many MDC operators have a strange belief that physical walls and
   firewalls provide sufficient security.  This is not credible.  All
   MDC protocols need to be examined for exposure and attack surface.

   It is generally unwise to assume that on the wire Ethernet is secure.
   Strange/unauthorized devices may plug into a port.  Mis-wiring is
   very common in datacenter installations.  A poisoned laptop might be
   plugged into a device's port.

   Malicious nodes/devices could mis-announce addressing, form malicious
   associations, etc.

   For these reasons, the OPEN PDU's authentication data exchange SHOULD
   be used.  [ A mandatory to implement authentication is in
   development. ]

19.  IANA Considerations

   This document requests the IANA create a registry for LSOE PDU Type,
   which may range from 0 to 255.  The name of the registry should be
   LSOE-PDU-Type.  The policy for adding to the registry is RFC Required
   per [RFC5226], either standards track or experimental.  The initial
   entries should be the following:

           PDU
           Code    PDU Name
           ----    -------------------
           0        HELLO
           1        OPEN
           2        KEEPALIVE
           3        ACK
           4        IPv4 Announce / Withdraw
           5        IPv6 Announce / Withdraw
           6        MPLS IPv4 Announce / Withdraw
           7        MPLS IPv6 Announce / Withdraw
           8-255    Reserved



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   This document requests the IANA create a registry for LSOE PL Flag
   Bits, which may range from 0 to 7.  The name of the registry should
   be LSOE-PL-Flag-Bits.  The policy for adding to the registry is RFC
   Required per [RFC5226], either standards track or experimental.  The
   initial entries should be the following:

           Bit     Bit Name
           ----    -------------------
           0       Primary
           1       Loopback
           2-7     Reserved

20.  IEEE Considerations

   This document requires a new EtherType.

21.  Acknowledgments

   The authors thank Cristel Pelsser for multiple reviews, Jeff Haas for
   review and comments, Joe Clarke for a useful review, John Scudder
   deeply serious review and comments, Larry Kreeger for a lot of layer
   2 clue, Martijn Schmidt for his contribution, Russ Housley for
   checksum discussion and sBox, and Steve Bellovin for checksum advice.

22.  References

22.1.  Normative References

   [I-D.ietf-idr-bgp-ls-segment-routing-ext]
              Previdi, S., Talaulikar, K., Filsfils, C., Gredler, H.,
              and M. Chen, "BGP Link-State extensions for Segment
              Routing", draft-ietf-idr-bgp-ls-segment-routing-ext-11
              (work in progress), October 2018.

   [I-D.ietf-idr-bgpls-segment-routing-epe]
              Previdi, S., Talaulikar, K., Filsfils, C., Patel, K., Ray,
              S., and J. Dong, "BGP-LS extensions for Segment Routing
              BGP Egress Peer Engineering", draft-ietf-idr-bgpls-
              segment-routing-epe-17 (work in progress), October 2018.

   [I-D.ietf-lsvr-bgp-spf]
              Patel, K., Lindem, A., Zandi, S., and W. Henderickx,
              "Shortest Path Routing Extensions for BGP Protocol",
              draft-ietf-lsvr-bgp-spf-03 (work in progress), September
              2018.






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   [RFC1982]  Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982,
              DOI 10.17487/RFC1982, August 1996,
              <http://www.rfc-editor.org/info/rfc1982>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC3032]  Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
              Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
              Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001,
              <http://www.rfc-editor.org/info/rfc3032>.

   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271,
              DOI 10.17487/RFC4271, January 2006,
              <http://www.rfc-editor.org/info/rfc4271>.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", RFC 5226,
              DOI 10.17487/RFC5226, May 2008,
              <http://www.rfc-editor.org/info/rfc5226>.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <http://www.rfc-editor.org/info/rfc5880>.

   [RFC6286]  Chen, E. and J. Yuan, "Autonomous-System-Wide Unique BGP
              Identifier for BGP-4", RFC 6286, DOI 10.17487/RFC6286,
              June 2011, <http://www.rfc-editor.org/info/rfc6286>.

   [RFC7752]  Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
              S. Ray, "North-Bound Distribution of Link-State and
              Traffic Engineering (TE) Information Using BGP", RFC 7752,
              DOI 10.17487/RFC7752, March 2016,
              <http://www.rfc-editor.org/info/rfc7752>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <http://www.rfc-editor.org/info/rfc8174>.

22.2.  Informative References








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   [JUPITER]  Singh, A., Germano, P., Kanagala, A., Liu, H., Provost,
              J., Simmons, J., Tanda, E., Wanderer, J., HAP.lzle, U.,
              Stuart, S., Vahdat, A., Ong, J., Agarwal, A., Anderson,
              G., Armistead, A., Bannon, R., Boving, S., Desai, G., and
              B. Felderman, "Jupiter rising", Communications of the
              ACM Vol. 59, pp. 88-97, DOI 10.1145/2975159, August 2016.

Authors' Addresses

   Randy Bush
   Arrcus & IIJ
   5147 Crystal Springs
   Bainbridge Island, WA  98110
   United States of America

   Email: randy@psg.com


   Rob Austein
   Arrcus, Inc

   Email: sra@hactrn.net


   Keyur Patel
   Arrcus
   2077 Gateway Place, Suite #400
   San Jose, CA  95119
   United States of America

   Email: keyur@arrcus.com




















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