Igmp Version 1; Igmp Version 2; Understanding Pim; Pim Versions - Cisco 3845 - Security Bundle Router Software Manual

Chapter 33 Configuring IP Multicast Routing

IGMP Version 1

IGMP Version 1 (IGMPv1) primarily uses a query-response model that enables the multicast router and
multilayer switch to find which multicast groups are active (have one or more hosts interested in a
multicast group) on the local subnet. IGMPv1 has other processes that enable a host to join and leave a
multicast group. For more information, see RFC 1112.

IGMP Version 2

IGMPv2 extends IGMP functionality by providing such features as the IGMP leave process to reduce
leave latency, group-specific queries, and an explicit maximum query response time. IGMPv2 also adds
the capability for routers to elect the IGMP querier without depending on the multicast protocol to
perform this task. For more information, see RFC 2236.

Understanding PIM

PIM is called protocol-independent: regardless of the unicast routing protocols used to populate the
unicast routing table, PIM uses this information to perform multicast forwarding instead of maintaining
a separate multicast routing table.
PIM is defined in RFC 2362, Protocol-Independent Multicast-Sparse Mode (PIM-SM): Protocol
Specification. PIM is defined in these Internet Engineering Task Force (IETF) Internet drafts:
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This section includes this information about PIM:
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PIM Versions

PIMv2 includes these improvements over PIMv1:
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OL-23400-01
Protocol Independent Multicast (PIM): Motivation and Architecture
Protocol Independent Multicast (PIM), Dense Mode Protocol Specification
Protocol Independent Multicast (PIM), Sparse Mode Protocol Specification
draft-ietf-idmr-igmp-v2-06.txt, Internet Group Management Protocol, Version 2
draft-ietf-pim-v2-dm-03.txt, PIM Version 2 Dense Mode
PIM Versions, page 33-3
PIM Modes, page 33-4
PIM Stub Routing, page 33-5
IGMP Helper, page 33-5
Auto-RP, page 33-6
Bootstrap Router, page 33-6
Multicast Forwarding and Reverse Path Check, page 33-7
A single, active rendezvous point (RP) exists per multicast group, with multiple backup RPs. This
single RP compares to multiple active RPs for the same group in PIMv1.
A bootstrap router (BSR) provides a fault-tolerant, automated RP discovery and distribution
mechanism that enables routers and multilayer switches to dynamically learn the group-to-RP
mappings.
Understanding Cisco's Implementation of IP Multicast Routing
Cisco ME 3800X and 3600X Switch Software Configuration Guide
33-3