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Community Member

Process Switching

Hi There,

If I apply access-lists to interfaces on a 3600 router, am I essentially turning off fast switching off for those interfaces as all packets have to be checked for matches or do access-list make no difference at all to fast switching. Also, how does priority queuing affect fast switching as it rearranges the order of packets.

Any advice appreciated

Karl Jones

Community Member

Re: Process Switching

Hello Karl,

Check out this link on switching. You want to look at netflow for combining access lists and maintaining some fast switching functionality:

I hope someone else can answer the part of your question about priority queuing. I think that switching decisions and queuing decisions are apples and oranges but I can't say for sure.

Community Member

Re: Process Switching

Thanks Scott,

I will check out that link,

Happy New Year

Community Member

Re: Process Switching

If im right, it doesn't affect fast switching at all. I know ACLs cannot be used with CEF switching unless in conjunction with a policy. The good thing is it would not instantly divert to process switching, it would drop to each previous switching successor in terms of speed. Not all packets would be process-switched anyway because the "stream characteristics", e.g. src/dest/port, etc. would be cached preventing the need for every packet from each stream being compared to the ACL.

Hope this helps,

Neil Moss.

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