Table of Contents
Advertisement
Chapter 34
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:
•
•
•
•
•
PIM Versions
PIMv2 includes these improvements over PIMv1:
•
•
•
•
•
•
•
78-17058-01
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
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.
Sparse mode and dense mode are properties of a group, as opposed to an interface. We strongly
recommend sparse-dense mode, as opposed to either sparse mode or dense mode only.
PIM join and prune messages have more flexible encoding for multiple address families.
A more flexible hello packet format replaces the query packet to encode current and future
capability options.
Register messages to an RP specify whether they are sent by a border router or a designated router.
PIM packets are no longer inside IGMP packets; they are standalone packets.
Understanding Cisco's Implementation of IP Multicast Routing
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
34-3
Hide quick links:
Advertisement
Table of Contents
Troubleshooting
