Foundry Networks AR3202-CL - Manual (Page 221)

Foundry AR-Series Router User Guide
14 - 4 © 2004 Foundry Networks, Inc. June 2004
Protocol Independent Multicast - Source Specific Multicast (PIM-SSM)
By running PIM-SSM and IGMPv3, you can implement a Source Specific Multicast (SSM) service model in your
network. PIM-SSM functionality is the subset of PIM-SM functionality dealing only with source-specific distribution
trees. IGMPv3 provides a way to detect channel subscriptions; for example, host-initiated (S,G) joins where G falls
within the defined range of SSM multicast group addresses.
PIM-SSM can be run in the absence of IGMPv3. Even when they are both running, they do not need to run on the
same interfaces. For example, you might not want to run PIM-SSM (or PIM-SM, for that matter) over an interface
that leads to a stub network. Similarly, if a network cannot contain local IGMPv3 receivers (for example, on a DMZ
network), then there is no need to run IGMPv3.
The PIM-SSM command is ip pim ssm-range.
Internet Group Management Protocol (IGMP)
Internet Group Management Protocol (IGMP) is enabled on hosts and routers that want to receive multicast traffic.
IGMP informs locally-attached routers of their multicast group memberships. Hosts inform routers of the groups of
which they are members by multicasting IGMP Group Membership Reports. When multicast routers listen for
these reports, they can exchange group membership information with other multicast routers. This reporting
system allows distribution trees to be formed to deliver multicast datagrams. The original version of IGMP was
defined in RFC 1112, Host Extensions for IP Multicasting. Extensions to IGMP, known as IGMP version 2.
IGMPv2 improves performance and supports the following message types:
• IGMP Query: IGMP Query is sent by the router to know which groups have members on the attached
network.
• IGMP Reports: IGMP reports are sent as a response to the query by hosts to announce their group
membership. Reports can be sent “unsolicited” when the hosts come up.
• IGMP Leaves: IGMP Leaves are sent by the host when it relinquishes membership of a group.
The latest extension to the IGMP standard is Version 3, which includes interoperability with version 2 and version
1 hosts, also provides support for source filtering. Source filtering enables a multicast receiver host to signal to a
router which groups it wants to receive multicast traffic from, and from which source(s) this traffic is expected. This
Display PIM Candidate
RP info Foundry#show ip pim crp-info
Display PIM statistics Foundry#show ip pim statistics
Display PIM RP set Foundry#show ip pim rp-set
Display PIM Static RP Foundry#show ip pim rp
Trace PIM packets Foundry# debug ip pim packet <pkt_type# <direction#
[interface_name ] [ dlci ]
Trace PIM state
changes Foundry# debug ip pim state
Trace PIM routes Foundry# debug ip pim route
Trace PIM detail Foundry# debug ip pim detail
Trace PIM debug Foundry# debug ip pim debug
All Traces Foundry#debug ip pim all
T ABLE 5 PIM S HOW AND D EBUG C OMMANDS (C ONTINUED )