S/M, 224/4 - Cisco Catalyst 4500 series Administration Manual

Chapter 37 Configuring IP Multicast
it is a virtual interface that the MFIB subsystem creates to indicate that packets are being tunnelled to
the specified destination address. A PimTunnel interface cannot be displayed with the normal show
interface command.

S/M, 224/4

An (S/M, 224/4) entry is created in the MFIB for every multicast-enabled interface. This entry ensures
that all packets sent by directly connected neighbors can be register-encapsulated to the PIM-SM RP.
Typically, only a small number of packets are forwarded using the (S/M,224/4) route, until the (S,G)
route is established by PIM-SM.
For example, on an interface with IP address 10.0.0.1 and netmask 255.0.0.0, a route is created matching
all IP multicast packets in which the source address is anything in the class A network 10. This route can
be written in conventional subnet/masklength notation as (10/8,224/4). If an interface has multiple
assigned IP addresses, then one route is created for each such IP address.
Multicast HA
Starting with Release IOS XE 3.4.0SG and IOS 15.1(2)SG, the Catalyst 4500/4900/4900X Series
switches support multicast HA, which ensures uninterrupted multicast traffic flow in the event of a
supervisor engine failure. MFIB states are synced to the standby supervisor engine prior to a switchover,
ensuring NSF availability with a fast convergence upon switchover during a supervisor engine failure.
Multicast HA (SSO / NSF / ISSU) is supported for the PIM Sparse, Dense, Bidir, and SSM Modes; and
at Layer 2 for IGMP and MLD Snooping.
For details on Multicast HA, please refer to the following URLs:
http://www.cisco.com/en/US/docs/ios-xml/ios/ipmulti_resil/configuration/xe-3s/imc_high_availability.
html
Configuring IP Multicast Routing
The following sections describe IP multicast routing configuration tasks:
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For more detailed information on IP multicast routing, such as Auto-RP, PIM Version 2, and IP multicast
static routes, refer to the Cisco IOS IP and IP Routing Configuration Guide, Cisco IOS Release 12.3.
Default Configuration in IP Multicast Routing
Table 37-1
OL_28731-01
Default Configuration in IP Multicast Routing, page 37-13
Enabling IP Multicast Routing, page 37-14
Enabling PIM on an Interface, page 37-14
Enabling Bidirectional Mode, page 37-16
Enabling PIM-SSM Mapping, page 37-17
Configuring a Rendezvous Point, page 37-17
Configuring a Single Static RP, page 37-20
Load Splitting of IP Multicast Traffic, page 37-22
shows the IP multicast default configuration.
Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)E
Configuring IP Multicast Routing
37-13