A very quick multicast routing ASA 9.1.X

In this post we will look at mcast routing within a ASA. It's quite simple to enable.

1st We identify the interfaces to enable for multicast. Here we will be doing our  vlan1,2, & 3 on a ASA5505. The configuration looks like this;

2nd we must enable multicast routing globaly

config t
 multicast routing 
end


And lastly, we check our configurations with a few show commands;

 

 By default we are enabled for IGMPv2 and  you can select version if so desired. The ASA does not support SSM or IGMPv3.

You can validate the  mcast table via the show cmd  "show mroute".

 
As with unicast traffic & policies, you will need  acl entries to allow multicast traffic to pass.

e.g
!

access-list out2in extended permit ip any host 224.2.2.11

!

Key gotchas to be aware with multicast routing;

 TTL expirations

 multicast boundaries filters

 the appropiate fwpolicies and direction

 igmp filter

 rpf checks  ( reverse path forward checks )

 src-network/host must be in your route  table

Ken Felix
kfelix  ---a---t---hyperfeed---dot----com

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