S/M, 224/4 - Cisco Catalyst 4500 Series Configuration Manual

Configuring IP Multicast Routing
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Note When PIM-SM routing is in use, the MFIB route might include an interface as in this example:
PimTunnel [1.2.3.4].
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.
Restrictions on Using Bidirectional PIM
Restrictions include the following:
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Configuring IP Multicast Routing
The following sections describe IP multicast routing configuration tasks:
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Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SG
35-12
Forwarding (F)—Used in conjunction with the Accepting (A) flag as described above. The set of
Forwarding interfaces that form what is often referred to as the multicast "olist" or output interface
list.
Signaling (S)—Sets on an interface when some multicast routing protocol process in Cisco IOS
needs to be notified of packets arriving on that interface.
Starting with Release IOS XE 3.3.0SG and IOS 15.1(1)SG, the seven RP restriction was removed.
IPv4 Bidirectional (Bidir) PIM is supported on Catalyst 4900M, Catalyst 4948E, Supervisor Engine
6-E, Supervisor Engine 6L-E, Supervisor Engine 7-E, and Supervisor Engine 7L-E. IPv6 Bidir PIM
is not supported.
Default Configuration in IP Multicast Routing, page 35-13
Enabling IP Multicast Routing, page 35-13
Enabling PIM on an Interface, page 35-14
Enabling Bidirectional Mode, page 35-15
Enabling PIM-SSM Mapping, page 35-16
Configuring a Rendezvous Point, page 35-16
Configuring a Single Static RP, page 35-20
Chapter 35 Configuring IP Multicast
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