[c-nsp] Conditional advertise-map

[Richard Mikisa]

On Wed, Sep 15, 2010 at 5:38 PM, Heath Jones <hj1980 at gmail.com> wrote:
> Richard,
> Is the arrangement that 36997 will provide a backup service for you, so its
> a last resort to pull traffic through them? If that is the case, have you
> tried prepending your advertisments towards 36997?

Yes, arrangement is to you them as a fall back option. Prepend is what
i intend to try now.

> Also, I can see from global bgp they are not peering with eachother so its
> not a situation where communities could help. The other solution is to
> advertise a supernet to 36997 and break this in half and advertise both
> subnets to 5511 (assuming you have a decent sized prefix >/24).

Can't do this because I have some customers downstream whose's
prefixes I can't break up yet they insist that they only want to use
the AS511 link.

>
> Perhaps you have already tried these solutions, or don't want to head that
> way, i'm not sure :)
>
> I'll check this one out actually (your advertise map) - its a good situation
> to lab up and try!
> If you are having problems because of the access lists trying to prevent
> re-advertisment of routes, you could tag them when they come in instead (add
> community), and filter them out on egress...
>
> Hope this helps.

Thanks

>
>
>
>
> On 15 September 2010 09:08, Richard Mikisa <rmikisa at gmail.com> wrote:
>>
>> Hi all,
>>
>> I have a scenario where I have two upstreams ASN5511 and ASN36997.
>> Both do send me a default route and I choose ASN5511 as the best path.
>> All my outbound traffic is via ASN5511 and the return is distributed
>> between the two. What I want however is to use an advertise map so I
>> ONLY advertise my prefixes to ASN5511 so I only use his link but
>> fail-over to advertising my prefixes to ASN36997 in the event ASN5511
>> fails.
>>
>> I have created the the two route-maps to be matched NO_DEFAULT_FT and
>> AS_LIST and configured as below.
>>
>> ## access list below is to avoid me feeding back to my up-streams
>> the routes learned from other up-streams. That way I only advertise
>> to the up-streams only prefixes from me and my down-streams.
>>
>> ip as-path access-list 10 deny ^5511_
>> ip as-path access-list 10 deny ^12455_
>> ip as-path access-list 10 deny ^36997_
>> ip as-path access-list 10 permit .*
>> !!
>> ## Match against filter below. If anything from ASN5511 is available,
>>
>> ip as-path access-list 20 permit ^5511_
>> !!
>>
>> route-map NO_DEFAULT_FT permit 10
>> match as-path 20
>> !!
>> route-map AS_LIST permit 10
>> match as-path 10
>> !!
>> neighbor 41.222.1.33 advertise-map AS_LIST non-exist-map NO_DEFAULT_FT
>>
>>
>> Any ideas why it doesn't work.
>>
>> PS. Am working on drawing :)
>>
>> --
>> cheers
>> Richard
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>
>



-- 
cheers
Richard