CEF & Multicast

[Yong Peng]

Hi All,

Can multicast be supported by CEF switching? or it can be supported by fast switching/process switching?

Thanks.

[Arumugam Muthaiah]

Hi

CEF does not support IP multicast traffic. Therefore, any features that are dependent on the CEF path may not be applicable to IP multicast

Fast Switching

In multicast fast switching, the routing cache must store information for the source, multicast group, and multiple outgoing interfaces. Unicast fast switching needs to maintain only a cache for the destination address with a single outgoing interface

Multicast Distributed Fast Switching

Multicast Distributed Fast Switching (MDFS) is also known as Multicast Distributed Switching (MDS).

In Multicast Distributed Fast Switching (MDFS), packets are distributed switched on platforms with line cards. This methodology reduces the load on the Router Processor (RP), which now need only perform route lookups

IP Multicast Multilayer Switching

IP multicast Multilayer Switching is also known as IP multicast MLS and MMLS

IP multicast MLS is hardware-based, Layer 3 switching of IP multicast data for routers connected to high-end Catalyst LAN switches. IP multicast MLS switches IP multicast data packet flows between IP subnets using advanced ASIC switching hardware, thereby off-loading processor-intensive, multicast packet routing from network routers

Refer:

http://www.cisco.com/en/US/docs/ios/solutions_docs/ip_multicast/White_papers/sw_paths.html#wp1028646

Regards,

Aru

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[Yong Peng]

Hi Arumugam Muthaiah,

Got it, thanks a lot.

[Peter Paluch]

Hi Arumugam,

With IOS 12.4(20)T, the unicast IP Fast Cache support has been dropped. Do the router platforms that use this or newer IOS still use multicast IP Fast Cache for multicast routing?

Also, are there any plans to support multicast routing in CEF? Technically, it is possible - the question is whether Cisco is planning to implement it.

Thank you!

Best regards,

Peter