RE: [j-nsp] OC-192 Perf issues with ACL's

From: Morgan, Richard (rmorgan@orchestream.com)
Date: Thu Mar 08 2001 - 06:25:59 EST


> Now, you can of course construct really really bad access
> lists that will
> break any kind of tree look up and if you do this (as
> competitors might)
> then performance sucks. If on the other hand you use *real*
> filters (even
> several 100s of terms long) it works at line rate.

Can you give us an example of an access list that breaks a tree lookup ?

I understand that each term in a filter is evaluated in turn, thus a filter
with 100 terms requires 100 lookups. See the example below, I have two
identical filters do these have the same performance ?

Rich

/*
        Does one longest match first lookup
*/
filter fast {
        term 1 {
                from {
                        address 10.0.0.0
                        address 11.0.0.0
                        address 12.0.0.0
                }
                then {
                        discard;
                }
        }
}

/*
        Does three longest match first lookups
*/
filter slow {
        term 1 {
                from {
                        address 10.0.0.0
                }
                then {
                        discard;
                }
        term 2 {
                from {
                        address 11.0.0.0
                then {
                        discard;
                }

        term 3 {
                from {
                        address 12.0.0.0
                }
                then {
                        discard;
                }
        }
}
        

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