[c-nsp] Filtering BGP routes with route-map vs. not getting them in

[Michael K. Smith - Adhost]

Hello Otis:

I meant to account for his provider prepending their AS, not him
prepending his AS. :-)  So, if his upstream is NTT, he would get 2914
2914 11274 as well as 2914 11274.

Regards,

Mike

> -----Original Message-----
> From: OCOSA ListAcct [mailto:listacc at ocosa.com]
> Sent: Friday, July 06, 2007 3:28 PM
> To: Michael K. Smith - Adhost
> Cc: Kristian Kielhofner; cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] Filtering BGP routes with route-map vs. not
> getting them in
> 
> Mike,
> 
> I am not understanding what you are asking here? Explain please....
> 
> Prepending would only give Kris a longer as path...making others
prefer
> Kris shorter path over that one. I believe his goal is to get full
> routes and do what he pleases. But use all 120,000 once he gets a
> bigger
> router. I think it's 120,000 maybe more or less.
> 
> Actually if Kris' upstream did communities with him he could get
> customers routes and default that way....much cleaner I think....
> 
> Otis
> 
> 
> 
> Michael K. Smith - Adhost wrote:
> > For customer only routes wouldn't this be better to account for
> > prepending?
> >
> > Ip as-path access-list 5 permit ^(providerAS_)+([0-9_])+$
> >
> > Regards,
> >
> > Mike
> >
> >
> >> -----Original Message-----
> >> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-
> >> bounces at puck.nether.net] On Behalf Of OCOSA ListAcct
> >> Sent: Friday, July 06, 2007 12:03 PM
> >> To: Kristian Kielhofner
> >> Cc: cisco-nsp at puck.nether.net
> >> Subject: Re: [c-nsp] Filtering BGP routes with route-map vs. not
> >> getting them in
> >>
> >> True if really want to use option b...
> >>
> >> use this string to get routes directly connected to your upstream
or
> >> originated.
> >>
> >> ip as-path access-list 5 permit ^upstream as goes here_[0-9]*$
> >>
> >> or
> >>
> >>
> >> to deny any networks originated form your upstream...and allows
> >> everything else which could be bad if your router does not have at
> >> least
> >> 512MB
> >>
> >> ip as-path access-list 6 deny _upstream as goes here$
> >> ip as-path access-list 6 permit .*
> >>
> >>
> >> If I remember correctly you can also limited the amount of prefixes
> a
> >> neighbor can send you...
> >>
> >> router bgp as number
> >> nei x.x.x.x maximum-prefixes and the rest....
> >>
> >> I think the command is
> >>
> >>
> >> Otis
> >>
> >> Kristian Kielhofner wrote:
> >>
> >>> Hello everyone,
> >>>
> >>>   I'm back with another stupid "BGP on a 3750" question.  I need
> >>> "customer only routes" to the few providers that I have.  From
what
> >>>
> > I
> >
> >>> can tell, I'd end up with far less than the 8,000 max routes this
> >>> platform can handle.  I have two options when configuring this:
> >>>
> >>> a)  When bringing up the BGP session, I can request aggregated
> >>> customer-only routes (what I want).
> >>>
> >>> or...
> >>>
> >>> b)  I can request a full table and filter them myself with route-
> map
> >>> statements (I think).
> >>>
> >>>   With "a" I will have a much simpler configuration (not that it
> >>> matters much).  Will the 3750 have problems even receiving these
> >>> routes, even if I am filtering them?  I can imagine all sorts of
> >>> potential nastiness with that configuration.
> >>>
> >>>   If not, I'd much rather go with option "b".  I would have more
> >>> control over my routing and it would be easier to upgrade to a
more
> >>> capable router in the future (less co-ordination with ISPs, just
> >>> remove route-map statements).  I like this idea more.  Can the
3750
> >>>
> >> do
> >>
> >>> it?  What would happen?
> >>>
> >>> Thanks!
> >>>
> >>>
> >>>
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> >>