RE: limit BGP prefixes sent to a neighbor

From: Dufour, Andre (Andre.Dufour@PAETEC.com)
Date: Thu Aug 07 2008 - 12:20:21 ART


Although communities, etc. may not fit the typical thought-process if
you are pegged in to a numbers mode, can they fit the end result that
you are looking for....?

Andre

 

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Roger RPF
Sent: Thursday, August 07, 2008 10:00 AM
To: 'Joseph Brunner'; 'Victor Cappuccio'
Cc: 'GS CCIE-Lab'
Subject: AW: limit BGP prefixes sent to a neighbor

Hmmmm...do I understand it wrong? Doing the limitation on Y does only
prevent Y from installing/accepting too many routes but it does not
prevent
X from sending too many routes, isn't it?

http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_bgp3.h
tml#
wp1014777

If my task says, that I have to configure it on X, limiting the ammount
of
routes he is sending, what then??

But I agree with you, I think it is just a misswording in the task. But
is
it not an interesting question at all? How to limit the sent routes?

regards

Roger

-----Urspr|ngliche Nachricht-----
Von: Joseph Brunner [mailto:joe@affirmedsystems.com]
Gesendet: Donnerstag, 7. August 2008 16:44
An: 'Roger RPF'; 'Victor Cappuccio'
Cc: 'GS CCIE-Lab'
Betreff: RE: limit BGP prefixes sent to a neighbor

>Sure, I know, I could configure on y neighbor x.x.x.x max-prefix 5 to
limit
>the received routes but the task says to limit the routes sent from x
to y.

Say it a few times to yourself. Doing the limitation on Y IS LIMITING
THE
ROUTES SENT from x to y!

So sometimes we need to think in both directions at the same time.

I would say that is what the workbook wanted.

-Joe

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Roger RPF
Sent: Thursday, August 07, 2008 5:55 AM
To: 'Victor Cappuccio'; 'Joseph Brunner'
Cc: 'GS CCIE-Lab'
Subject: AW: limit BGP prefixes sent to a neighbor

Hi all,

Well, interesting solution to define a vrf and specify the max prefixes
allowed in the vrf. So in this case I would never send more than the
specified amount. But the drawback, as Victor said, is that with this I
would also limit the max routes I can receive in this vrf (if I
understand
that correct).

My task is that router x should only advertise 5 routes to it's bgp
neighbor
y because y has not enough memory (just a fictive example). The 5 routes
are
not specified, so I don't know which one.

Sure, I know, I could configure on y neighbor x.x.x.x max-prefix 5 to
limit
the received routes but the task says to limit the routes sent from x to
y.

Hmmm....

thanks

Roger

-----Urspr|ngliche Nachricht-----
Von: Victor Cappuccio [mailto:vcappuccio@gmail.com]
Gesendet: Donnerstag, 7. August 2008 11:39
An: Joseph Brunner
Cc: Roger RPF; GS CCIE-Lab
Betreff: Re: limit BGP prefixes sent to a neighbor

Hi Jose,

Those 2 are also are used to set the maximum amount of prefixes
*received* and not only for information learned by a VRF via MP-BGP
between PE and PE or BGP between the PE and the CE, but also for any
routing context running between the PE and the CE routers. (rip, ospf
whateva), I think that an alternative to Roger question could be the
use of prefix-list and/or community lists and/or as-path list, but I
am not sure if there is any mechanism to control the Max number of
routes to *send* to a neighbor (say only 3 routes sent to neighbor X)

Good question...

On Thu, Aug 7, 2008 at 10:28 AM, Joseph Brunner
<joe@affirmedsystems.com>
wrote:
> Sure; (warning I'm goofy)
>
> Does this count?
>
> 1. config vrf
>
> ip vrf 1001
> rd 65000:1001
> route-target both 65000:1001
> maximum routes 1000 500 <- where we would limit to 1000, but warn at
500
>
>
> 2. Place interface into vrf
>
> Int s0/0
> Ip vrf forwarding xxxx
>
>
> Run afi ipv4 to push the vrf routes from this router to our neighbor
via
> bgp...
>
> Router bgp 65000
> Neighbor 1.1.1.1 remote-as 1
>
> address-family ipv4 unicast vrf 1001
> Neighbor 1.1.1.1 activate
>
>
> Of course if the other side of this router is to another bgp peer, you
could
> put that interface in a vrf, say that didn't have the max routes
configured,
> and add the route targets to get routes between the vrf's.
>
> -Joe
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Roger RPF
> Sent: Thursday, August 07, 2008 5:10 AM
> To: 'GS CCIE-Lab'
> Subject: limit BGP prefixes sent to a neighbor
>
> Hi group,
>
>
>
> Is there a way to limit the maximum amount of prefixes that BGP sends
to a
> neighbor? I know that with neighbor x.x.x.x max-prefix I can limit the
> received ones, but in sending direction?
>
>
>
> regards
>
>
>
> Roger
>
>
> Blogs and organic groups at http://www.ccie.net
>
>



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