A Distributed MARS Service Using SCSP
RFC 2443

Document Type RFC - Experimental (November 1998; No errata)
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Network Working Group                                         J. Luciani
Request for Comments: 2443                                  Bay Networks
Category: Experimental                                          A. Gallo
                                                                     IBM
                                                           November 1998

                 A Distributed MARS Service Using SCSP

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 (1998).  All Rights Reserved.

Abstract

   This document describes a method for distributing a MARS service
   within a LIS[1].  This method uses the Server Cache Synchronization
   Protocol (SCSP)[2] to synchronize the MARS Server databases within a
   LIS.  When SCSP is used to synchronize the caches of MARS Servers in
   a LIS, the LIS defines the boundary of an SCSP Server Group (SG).

1. Introduction

   The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
   SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
   document, are to be interpreted as described in [5].

   The MARS is an extended analog of the ATMARP Server introduced in
   [4]. It provides the necessary connection and addressing services
   required by layer 3 multicast services over ATM. There are three
   basic elements to the MARS model. First, the MARS Server which
   manages and distributes layer 3 group membership information to the
   LIS. Second, MARS Clients which register with and query a single MARS
   Server for layer 3 multicast information. Third, MCS Clients which
   register with a single MARS Server and provide layer 3 multicast
   forwarding services for a LIS.

   Both MARS Clients and MCS Clients explicitly register with the MARS
   Server before exchanging layer 3 multicast information. During the
   registration process MARS Clients are place on the Cluster Control VC

Luciani & Gallo               Experimental                      [Page 1]
RFC 2443                MARS Service Using SCSP            November 1998

   (CCVC) and MCS Clients are placed on the Server Control VC (SCVC).
   Both the CCVC and SCVC are then used to propagate layer 3 multicast
   updates to the clients which make up a LIS. During the registration
   process MARS Clients are also assigned a unique Cluster Member ID
   (CMI) which is used to identify reflected packets in the presence of
   MCS Clients.

   In the Distributed MARS Model there MAY be multiple MARS Servers in a
   given LIS, and since any MARS Server within the LIS MUST be able to
   provide layer 3 multicast information about any multicast group
   within the LIS, there MUST be a method by which to synchronize
   multicast information across all MARS Servers within the LIS.

   The Server Cache Synchronization Protocol (SCSP) solves the
   generalized server synchronization/cache-replication problem for
   distributed databases, and thus SCSP MAY be applied to the MARS
   Server database synchronization problem within a LIS. When SCSP is
   used to synchronize the caches of MARS Servers in a LIS, the LIS
   defines the boundary of and SCSP Server Group (SG).

   SCSP is defined in two parts: the protocol independent part and the
   client/server protocol specific part. The protocol independent part
   is specified in [2] whereas this document will specify the
   client/server protocol specific part where the MARS Server is the
   client/server protocol.

2. Overview

   All MARS Servers belonging to a LIS are said to belong to a Server
   Group (SG).  A SG is identified by, not surprisingly, its SGID which
   is contained in a field in all SCSP packets. All SCSP packets contain
   a Protocol ID (PID) field as well. This PID field is set to 0x0003 to
   signify that SCSP is synchronizing MARS Server databases as opposed
   to synchronizing some other protocol's databases. (see Section
   B.2.0.1 of [2] for more details).  In general, PIDs for SCSP will be
   assigned by IANA upon request given that a client/server protocol
   specific specification has been written. In the case of MARS Servers,
   the client/server protocol specific specification was written at the
   same time as SCSP, and thus a PID=0x0003 was assigned in [2].

   SCSP places no topological requirements upon a MARS Server SG.
   Obviously, however, the resultant graph of MARS Servers must span the
   set of MARS Servers being synchronized. For more information about
   the client/server protocol independent part of SCSP, the reader is
   encouraged to see [2].

Luciani & Gallo               Experimental                      [Page 2]
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