BGP Confederation config problem...

At each member AS, either IGRP or OSPF. They do not interact. By
design... two of the AS's are across the Pacific from the other two :slight_smile:

-Andy

Andy,

  I would say that you should switch to two confeds, one on either
side of the ocean. That should take care of the problem. BTW, did Minyah
ever get her NAT problem straightened out?

  -Blake

Hey Andy if it is a Confederation the BGP is treated like IBGP even if it
is EBGP so you can set a MED value to favor a specific route, you can also
manipulate the AS_PATH attribute - appending the AS number 2 or more times
to the announcement for the least favored route applied to the appropriate
interface.

Since it's all considerred IBGP simply set the MED to 50 on the least
favored and 20 on the favored - or what ever incriments you deem
appropriate.

You may have to set "bgp always-compare-med" for it to be considered on
multiple AS numbers within a confederation though.

But it isn't considered IBGP within the confederation. The router makes a
distinction between routes learned from an IBGP peer (internal) and a
confederation EBGP peer (confederation-external) and will ALWAYS pick the
external route, all other items above it in the selection list being
equal.

I've eliminated trying to increase the AS path, since it's ignored within
the confederation.

Setting the MED is the crux of the problem - I can set it "statically",
but the idea is to make the whole confederation dynamic. I want the
confederation to work like a true "internet". (Yes, I'm asking for the
world...)

-Andy

: Andy McConnell <andym@nttlabs.com> wrote as below
: at Mon, 9 Mar 1998 08:57:29 -0800 (PST) ;
:
:expressionless: But it isn't considered IBGP within the confederation. The router makes a
:expressionless: distinction between routes learned from an IBGP peer (internal) and a
:expressionless: confederation EBGP peer (confederation-external) and will ALWAYS pick the
:expressionless: external route, all other items above it in the selection list being
:expressionless: equal.
:expressionless:
:expressionless: I've eliminated trying to increase the AS path, since it's ignored within
:expressionless: the confederation.
:expressionless:
:expressionless: Setting the MED is the crux of the problem - I can set it "statically",
:expressionless: but the idea is to make the whole confederation dynamic. I want the
:expressionless: confederation to work like a true "internet". (Yes, I'm asking for the
:expressionless: world...)
:expressionless:

Andy, I agree with you. I run bgp-confederation in my
network with IGP in each subAS independant. In this case it
is helpful if ASpath length within confederation is
considered as true eBGP.

Now I set MED statically. Thank you for information of "set
metric +/-[VALUE]" statement, I'll try it.

Nowaday, iBGP Reflecter is preferred to BGP Confederation.
When we use single IGP within AS, reflecter and
confederation make little difference. But confederation
enable us to divide IGP into sub-ASes. It may make sense
a lot. And in such a network configuration, it is natural
that AS path length consideration while route selection is
required.

How do you like this idea?? Is it IDR topic??

:expressionless: -Andy
:expressionless:

I agree with you, Andy. I run bgp-confederation in my
network with IGP divided into subASes. Your situation is a
little bit different from mine without any iBGP sessions now.
But the problem is similar, AS path length is never
considered in route selection. I set MED statically.

  Thank you Avi and Andy for the information of "set metric
+/-[VALUE]" statement. I'll try it.

  Route reflecter and confederation seem similar to each
other to solve iBGP mesh problem, and nowaday reflecter is
preferred to confed. But I think confederation is great
since it enables us to divide IGP into subASes. And in such
a network configuration, it is natural that AS path length
is considered for the route selection.

  How do you like this idea, folks?

: Andy McConnell <andym@nttlabs.com> wrote as below
: at Mon, 9 Mar 1998 08:57:29 -0800 (PST) ;
:
:expressionless: But it isn't considered IBGP within the confederation. The router makes a
:expressionless: distinction between routes learned from an IBGP peer (internal) and a
:expressionless: confederation EBGP peer (confederation-external) and will ALWAYS pick the
:expressionless: external route, all other items above it in the selection list being
:expressionless: equal.
:expressionless:
:expressionless: I've eliminated trying to increase the AS path, since it's ignored within
:expressionless: the confederation.
:expressionless:
:expressionless: Setting the MED is the crux of the problem - I can set it "statically",
:expressionless: but the idea is to make the whole confederation dynamic. I want the
:expressionless: confederation to work like a true "internet". (Yes, I'm asking for the
:expressionless: world...)
:expressionless:
:expressionless: -Andy
:expressionless:

But it isn't considered IBGP within the confederation. The router makes a
distinction between routes learned from an IBGP peer (internal) and a
confederation EBGP peer (confederation-external) and will ALWAYS pick the
external route, all other items above it in the selection list being
equal.

I think you want the cisco "distance bgp" command.

--apb (Alan Barrett)