Supporting Mixed Bidirctional/Sparse-Mode Pim Networks; For More Information About Multicast Routing - Cisco FirePOWER ASA 5500 series Configuration Manual

Chapter 11 Configuring Multicast Routing
For example, the following commands prevent the 10.1.1.1 router from becoming a PIM neighbor on
interface GigabitEthernet0/3:
hostname(config)# interface GigabitEthernet0/3
hostname(config-if)# pim neighbor-filter pim_nbr

Supporting Mixed Bidirctional/Sparse-Mode PIM Networks

Bidirectional PIM allows multicast routers to keep reduced state information. All of the multicast routers
in a segment must be bidirectionally enabled in order for bidir to elect a DF.
The pim bidir-neighbor-filter command enables the transition from a sparse-mode-only network to a
bidir network by letting you specify the routers that should participate in DF election while still allowing
all routers to participate in the sparse-mode domain. The bidir-enabled routers can elect a DF from
among themselves, even when there are non-bidir routers on the segment. Multicast boundaries on the
non-bidir routers prevent PIM messages and data from the bidir groups from leaking in or out of the bidir
subset cloud.
When the pim bidir-neighbor-filter command is enabled, the routers that are permitted by the ACL are
considered to be bidir-capable. Therefore:
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To control which neighbors can participate in the DF election, perform the following steps:
Step 1 Use the access-list command to define a standard access list that permits the routers you want to
participate in the DF election and denies all others.
For example, the following access list permits the routers at 10.1.1.1 and 10.2.2.2 to participate in the
DF election and denies all others:
hostname(config)# access-list pim_bidir permit 10.1.1.1 255.255.255.255
hostname(config)# access-list pim_bidir permit 10.1.1.2 255.255.255.255
hostname(config)# access-list pim_bidir deny any
Step 2 Enable the pim bidir-neighbor-filter command on an interface.
The following example applies the access list created previous step to the interface GigabitEthernet0/3.
hostname(config)# interface GigabitEthernet0/3
hostname(config-if)# pim bidir-neighbor-filter pim_bidir

For More Information about Multicast Routing

The following RFCs from the IETF provide technical details about the IGMP and multicast routing
standards used for implementing the SMR feature:
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OL-10088-01
If a permitted neighbor does not support bidir, the DF election does not occur.
If a denied neighbor supports bidir, then DF election does not occur.
If a denied neighbor des not support bidir, the DF election occurs.
RFC 2236 IGMPv2
For More Information about Multicast Routing
Cisco Security Appliance Command Line Configuration Guide
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