RFC 1585 (rfc1585) - Page 1 of 13

MOSPF: Analysis and Experience

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Network Working Group                                             J. Moy
Request for Comments: 1585                                 Proteon, Inc.
Category: Informational                                       March 1994


                     MOSPF: Analysis and Experience

Status of this Memo

   This memo provides information for the Internet community.  This memo
   does not specify an Internet standard of any kind.  Distribution of
   this memo is unlimited.

Abstract

   This memo documents how the MOSPF protocol satisfies the requirements
   imposed on Internet routing protocols by "Internet Engineering Task
   Force internet routing protocol standardization criteria" ([RFC
   1264]).

   Please send comments to .

1.  Summary of MOSPF features and algorithms

   MOSPF is an enhancement of OSPF V2, enabling the routing of IP
   multicast datagrams.  OSPF is a link-state (unicast) routing
   protocol, providing a database describing the Autonomous System's
   topology.  IP multicast is an extension of LAN multicasting to a
   TCP/IP Internet.  IP Multicast permits an IP host to send a single
   datagram (called an IP multicast datagram) that will be delivered to
   multiple destinations.  IP multicast datagrams are identified as
   those packets whose destinations are class D IP addresses (i.e.,
   addresses whose first byte lies in the range 224-239 inclusive).
   Each class D address defines a multicast group.

   The extensions required of an IP host to participate in IP
   multicasting are specified in "Host extensions for IP multicasting"
   ([RFC 1112]).  That document defines a protocol, the Internet Group
   Management Protocol (IGMP), that enables hosts to dynamically join
   and leave multicast groups.

   MOSPF routers use the IGMP protocol to monitor multicast group
   membership on local LANs through the sending of IGMP Host Membership
   Queries and the reception of IGMP Host Membership Reports.  A MOSPF
   router then distributes this group location information throughout
   the routing domain by flooding a new type of OSPF link state
   advertisement, the group-membership-LSA (type 6). This in turn
   enables the MOSPF routers to most efficiently forward a multicast



Moy
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