[c-nsp] BGP Filter - Best Practice

[Ahmed Hilmy]

Hello Tony,

Thanks for your email, yes community is best way to filter BGP session
prefixes inside Backbone.

Regards,
Ahmed


On Fri, Apr 19, 2013 at 7:16 AM, Tony Tauber <ttauber at 1-4-5.net> wrote:

> Explicit prefix-lists should be used at the PE (customer edge).
> If some control is desired after that (or you foresee ever desiring same),
> tag the routes inbound on the customer edge with communities and control
> redistribution by filtering based on communities either internally or
> outbound to other BGP neighbors.
>
> Tony
>
>
> On Wed, Apr 17, 2013 at 3:35 PM, Ahmed Hilmy <hilmy.aa at gmail.com> wrote:
>
>> Hello Nick,
>>
>> Thanks for your reply, i am totally agree with you.
>>
>> Regards,
>> Ahmed
>>
>>
>> On Tue, Apr 16, 2013 at 9:12 PM, Nick Hilliard <nick at foobar.org> wrote:
>>
>> > On 15/04/2013 21:44, Ahmed Hilmy wrote:
>> > > I am using Prefix-list and as-path for BGP filter.
>> > > But if i  apply Prefix-list as inbound filter at PE, then from PE to
>> RR (
>> > > Route Reflector ) i apply as-path filter, i think it is more scalable
>> > than
>> > > modify Prefix-list continuously ? or use community ?
>> > > If my question not clear please ask me.
>> >
>> > it depends.
>> >
>> > Prefix lists are very fast because they are implemented as a trie, and
>> it
>> > is very fast to look up an entry in a trie.
>> >
>> > Community lists can be fast (standard, i.e. integer comparison) or slow
>> > (extended, i.e. regular expression).
>> >
>> > as-path lists are slow because they use regular expressions.
>> >
>> > If you need to filter BGP updates, it is usually fastest to use prefix
>> > lists or standard community lists.  It makes little difference whether
>> you
>> > use extended communities or as-path lists - both are slow.
>> >
>> > Nick
>> >
>> >
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