WB1 8.16 Filtering Auto-RP Messages

8.16 Filtering Auto-RP Messages

• Configure R1 so that SW4 cannot hear Auto-RP discovery messages.

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Auto-RP uses special dense-mode groups to disseminate RP information, and
the information is flooded across the multicast domain. The only way to control
the scope of the information is by setting the TTL to the value that roughly
represents the diameter of the multicast domain. However, the problem is that
this does not enforce strict administrative limits on the information scope, and
per-link flooding is not controlled. The other way to filter Auto-RP announcements
is to use the ip multicast boundary command, discussed in a separate
task.

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R1:
ip pim send-rp-discovery Loopback0 scope 2

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Ensure that SW2 still has entries in the Auto-RP cache while SW4 does not.
Please note that it may take as long as three minutes for these mappings to
expire from the rp mapping table.

Rack1SW4#show ip pim rp mapping
PIM Group-to-RP Mappings
This system is an RP (Auto-RP)
Rack1SW4#
 
Rack1SW2#show ip pim rp mapping
PIM Group-to-RP Mappings
This system is an RP (Auto-RP)
Group(s) 224.0.0.0/5
  RP 150.1.8.8 (?), v2v1
    Info source: 150.1.1.1 (?)
         Uptime: 00:02:03, expires: 00:00:56
Group(s) 224.0.0.0/4
  RP 150.1.10.10 (?), v2v1
    Info source: 150.1.1.1 (?)
         Uptime: 00:02:19, expires: 00:00:55
Group(s) (-)224.110.110.110/32
  RP 150.1.10.10 (?), v2v1
    Info source: 150.1.1.1 (?)
         Uptime: 00:02:19, expires: 00:00:55
Group(s) 232.0.0.0/5
  RP 150.1.10.10 (?), v2v1
    Info source: 150.1.1.1 (?)
         Uptime: 00:02:19, expires: 00:00:56
Rack1SW2#