rfc2835.txt

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Network Working Group                                        J.-M. Pittet
Request for Comments: 2835                          Silicon Graphics Inc.
Category: Standards Track                                        May 2000


                    IP and ARP over HIPPI-6400 (GSN)

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

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

Abstract

   The ANSI T11.1 task force has standardized HIPPI-6400 also known as
   Gigabyte System Network (GSN), a physical-level, point-to-point,
   full-duplex, link interface for reliable, flow-controlled,
   transmission of user data at 6400 Mbit/s, per direction. A parallel
   copper cable interface for distances of up to 40 m is specified in
   HIPPI-6400-PH [1].  Connections to a longer-distance optical
   interface are standardized in HIPPI-6400-OPT [3].

   HIPPI-6400-PH [1] defines the encapsulation of IEEE 802.2 LLC PDUs
   [10] and by implication, IP on GSN. Another T11.1 standard describes
   the operation of HIPPI-6400 physical switches HIPPI-6400-SC [2].
   T11.1 chose to leave HIPPI-6400 networking issues largely outside the
   scope of their standards; this document specifies the use of HIPPI-
   6400 switches as IP local area networks. This document further
   specifies a method for resolving IP addresses to HIPPI-6400 hardware
   addresses (HARP) and for emulating IP broadcast in a logical IP
   subnet (LIS) as a direct extension of HARP. Furthermore it is the
   goal of this memo to define a IP and HARP that will allow
   interoperability for HIPPI-800 and HIPPI-6400 equipment both
   broadcast and non-broadcast capable networks.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Definitions . . . . . . . . . . . . . . . . . . . . . . .   3
       2.1 Global concepts used  . . . . . . . . . . . . . . . .   3
       2.2 Glossary  . . . . . . . . . . . . . . . . . . . . . .   4



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RFC 2835            IP and ARP over HIPPI-6400 (GSN)            May 2000


   3.  IP Subnetwork Configuration . . . . . . . . . . . . . . .   5
       3.1 Background  . . . . . . . . . . . . . . . . . . . . .   5
       3.2 HIPPI LIS Requirements  . . . . . . . . . . . . . . .   6
   4.  Internet Protocol . . . . . . . . . . . . . . . . . . . .   7
       4.1  Packet Format  . . . . . . . . . . . . . . . . . . .   7
            4.1.1 IEEE 802.2 LLC . . . . . . . . . . . . . . . .   7
            4.1.2 SNAP . . . . . . . . . . . . . . . . . . . . .   7
            4.1.3 Packet diagrams  . . . . . . . . . . . . . . .   8
       4.2  HIPPI-6400 Hardware address: Universal LAN MAC addr.   9
       4.3  Maximum Transmission Unit - MTU  . . . . . . . . . .  10
   5.  HIPPI Address Resolution Protocol - HARP  . . . . . . . .  11
       5.1  HARP Algorithm . . . . . . . . . . . . . . . . . . .  12
            5.1.1 Selecting the authoritative HARP service . . .  12
            5.1.2 HARP registration phase  . . . . . . . . . . .  13
            5.1.3 HARP operational phase . . . . . . . . . . . .  14
       5.2  HARP Client Operational Requirements . . . . . . . .  15
       5.3  Receiving Unknown HARP Messages  . . . . . . . . . .  16
       5.4  HARP Server Operational Requirements . . . . . . . .  16
       5.5  HARP and Permanent ARP Table Entries . . . . . . . .  18
       5.6  HARP Table Aging . . . . . . . . . . . . . . . . . .  18
   6.  HARP Message Encoding . . . . . . . . . . . . . . . . . .  19
       6.1 Generic IEEE 802 ARP Message Format . . . . . . . . .  19
       6.2 HIPARP Message Formats  . . . . . . . . . . . . . . .  21
           6.2.1 Example Message encodings:  . . . . . . . . . .  23
           6.2.2 HARP_NAK message format . . . . . . . . . . . .  24
   7.  Broadcast and Multicast   . . . . . . . . . . . . . . . .  24
       7.1 Protocol for an IP Broadcast Emulation Server - PIBES  25
       7.2 IP Broadcast Address  . . . . . . . . . . . . . . . .  25
       7.3 IP Multicast Address  . . . . . . . . . . . . . . . .  25
       7.4 A Note on Broadcast Emulation Performance . . . . . .  26
   8.  HARP for Scheduled Transfer . . . . . . . . . . . . . . .  26
   9.  Security Consierations  . . . . . . . . . . . . . . . . .  26
   10. Open Issues . . . . . . . . . . . . . . . . . . . . . . .  27
   11.  HARP Examples  . . . . . . . . . . . . . . . . . . . . .  27
        11.1 Registr. Phase of Client Y on Non-broadcast Hardware 27
        11.2 Registr. Phase of Client Y on Broadcast-capable . .  28
        11.3 Operational Phase (phase II)  . . . . . . . . . . .  29
             11.3.1 Successful HARP_Resolve example  . . . . . .  29
             11.3.2 Non-successful HARP_Resolve example  . . . .  30
   12.  References . . . . . . . . . . . . . . . . . . . . . . .  31
   13.  Acknowledgments  . . . . . . . . . . . . . . . . . . . .  32
   14.  Author's Address . . . . . . . . . . . . . . . . . . . .  32
   15.  Full Copyright Statement . . . . . . . . . . . . . . . .  33








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RFC 2835            IP and ARP over HIPPI-6400 (GSN)            May 2000


1. Introduction

   HIPPI-6400 is a duplex data channel that can transmit and receive
   data simultaneously at nearly 6400 megabits per second. HIPPI-6400
   data transfers are segmented into micropackets, each composed of 32
   data bytes and 8 control bytes. HIPPI-6400 uses four multiplexed
   virtual channels. These virtual channels are allocated to control
   traffic, low latency traffic, and bulk traffic (see [1] for more
   details).

   Using small packets and four virtual channels, large file transfers
   cannot lock out a host or switch port for interactive traffic.
   HIPPI-6400 guarantees in order delivery of data. It also supports
   link-level and end-to-end checksumming and credit-based flow control.

   HIPPI-6400-PH defines a 20-bit interface for copper cables operating
   at 500 MBaud. This provides a user payload bandwidth of 6400 Mb/s
   (800,000,000 Bytes/sec) in each direction. [8]

   HIPPI-6400-SC [2] defines two types of switches: bridging and non-
   bridging. The bridging switches are required to support hardware
   broadcast.  Non-bridging switches are not required to support
   broadcast.  This memo allows for a coherent implementation of IP and
   HARP with both types of switches.

   Gigabyte System Network(TM) (GSN) is a marketing name for HIPPI-6400.
   It is a trademark of the High Performance Networking Forum (HNF;
   http://www.hnf.org) for use by its member companies that supply
   products complying to ANSI HIPPI-6400 standards.

2  Definitions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC-2119 [19].

2.1 Global concepts used

   In the following discussion, the terms "requester" and "target" are
   used to identify the port initiating the address resolution request
   and the port whose address it wishes to discover, respectively. This
   document will use HIPPI-800 and HIPPI-6400 when referring to concepts
   that apply to one or the other technology. The term HIPPI will be
   used when referring to both technologies.

   Values are decimal unless otherwise noted. Formatting follows IEEE
   802.1A canonical bit order and HIPPI-6400-PH bit and byte ordering.




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RFC 2835            IP and ARP over HIPPI-6400 (GSN)            May 2000


2.2 Glossary

   Broadcast

   A distribution mode which transmits a message to all ports. The
   sending port is part of "all" and will therefore also receive a copy
   of the sent message.

   Classical/Conventional

   Both terms are used with respect to networks, including Ethernet,
   FDDI, and other 802 LAN types, as distinct from HIPPI-SC LANs.

   Destination

   The HIPPI port that receives data from a HIPPI Source.

   HARP

   HARP (HIPPI Address Resolution Protocol describes the whole set of
   HIPPI-6400 address resolution encodings and algorithms defined in
   this memo. HARP is a combination and adaptation of the Internet
   Address Resolution Protocol (ARP) RFC-826 [14] and Inverse ARP
   (InARP) [5] (see section 5). HARP also describes the HIPPI (800 and
   6400) specific version of ARP (i.e. the protocol and the HIPPI
   specific encoding).

   HARP table

   Each host has a HARP table which contains the IP to hardware address
   mapping of IP members.

   HRAL

   The HARP Request Address List.  A list of ULAs to which HARP messages
   are sent when resolving names to addresses (see section 3.2).

   Hardware (HW) address

   The hardware address of a port; it consists of an ULA (see section
   4.2). Note: the term port as used in this document refers to a HIPPI
   port and is roughly equivalent to the term "interface" as commonly
   used in other IP documents.

   Host

   An entity, usually a computer system, that may have one or more HIPPI
   ports and which may serve as a client or a HARP server.



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RFC 2835            IP and ARP over HIPPI-6400 (GSN)            May 2000


   Port

   An entity consisting of one HIPPI Source/Destination dual simplex
   pair that is connected by parallel or serial HIPPI to a HIPPI-SC
   switch and that transmits and receives IP datagrams.  A port may be
   an Internet host, bridge, router, or gateway.

   PIBES

   The Protocol for Internet Broadcast Emulation Server (see section 7).

   Source

   The HIPPI port that generates data to send to a HIPPI Destination.

   Universal LAN MAC Address (ULA)

   A 48-bit globally unique address, administered by the IEEE, assigned
   to each port on an Ethernet, FDDI, 802 network, or HIPPI-SC LAN.

3.  IP Subnetwork Configuration

3.1 Background

   ARP (address resolution protocol) as defined in [14] was meant to
   work on the 'local' cable. This definition gives the ARP protocol a
   local logical IP subnet (LIS) scope. In the LIS scenario, each
   separate administrative entity configures its hosts and routers
   within the LIS. Each LIS operates and communicates independently of
   other LIS's on the same HIPPI-6400 network.

   HARP has LIS scope only and serves all ports in the LIS.
   Communication to ports located outside of the local LIS is usually
   provided via an IP router. This router is a HIPPI-6400 port attached
   to the HIPPI-6400 network that is configured as a member of one or
   more LIS's. This configuration MAY result in a number of disjoint
   LIS's operating over the same HIPPI-6400 network. Using this model,
   ports of different IP subnets SHOULD communicate via an intermediate
   IP router even though it may be possible to open a direct HIPPI-6400
   connection between the two IP members over the HIPPI-6400 network.
   This is an consequence of using IP and choosing to have multiple
   LIS's on the same HIPPI-6400 fabric.

   By default, the HARP method detailed in section 5 and the classical
   LIS routing model MUST be available to any IP member client in the
   LIS.





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RFC 2835            IP and ARP over HIPPI-6400 (GSN)            May 2000


3.2 HIPPI LIS Requirements

   The requirement for IP members (hosts, routers) operating in a
   HIPPI-6400 LIS configuration is:

   o  All members of the LIS SHALL have the same IP network/subnet
      address and address mask [4].

   The following list identifies the set of HIPPI-6400-specific
   parameters that MUST be implemented in each IP station connected to
   the HIPPI-6400 network:

   o  HIPPI-6400 Hardware Address:

      The HIPPI-6400 hardware address (a ULA) of an individual IP
      endpoint (i.e. a network adapter within a host) MUST be unique in
      the LIS.

   o  HARP Request Address List (HRAL):

   The HRAL is an ordered list of two or more addresses identifying the
   address resolution service(s).  All HARP clients MUST be configured
   identically, i.e. all ports MUST have the same addresses(es) in the
   HRAL.

   The HRAL MUST contain at least two HIPPI HW addresses identifying the
   individual HARP service(s) that have authoritative responsibility for
   resolving HARP requests of all IP members located within the LIS.  By
   default the first address MUST be the reserved address for broadcast,
   i.e. FF:FF:FF:FF:FF:FF.

   The second address MUST be the standard HW address for the HARP