bgp feed to customer
Jim Gonzalez
jim at impactbusiness.com
Mon Jun 13 20:54:19 UTC 2011
-----Original Message-----
From: William Herrin [mailto:bill at herrin.us]
Sent: Monday, June 13, 2011 3:34 PM
To: Richard Zheng
Cc: nanog at nanog.org
Subject: Re: bgp feed to customer
On Mon, Jun 13, 2011 at 1:25 PM, Richard Zheng <rzheng at gmail.com> wrote:
> This is probably a typical setup for border router not speaking BGP,
> wonder how to handle it properly. Border router B is connected with
> customer router C. Router C wants default-only/partial/full routes.
> Router B can't or is not willing to handle it. Router C has a multihop
> EBGP session with a backbone router A. To get router B know the
> customer routes, router A redistributes them from EBGP to OSPF.
>
> The issue is redistribution from EBGP to OSPF works half way. OSPF
> database has the external routes, but forwarding address is set to
> Router A. So the routing loop occurs between A and B.
>
> I wonder if it is a design issue or configuration issue?
>
> ---------- --------------
> ------------
> | BGP rtr A | ============ | no-BGP rtr B | ============ | Customer
> | C |
> ---------- --------------
> ------------
Hi Richard,
Just a SWAG, but run IBGP on router B with just your internal routes
(including the customer route) instead of exporting into OSPF?
Regards,
Bill Herrin
--
William D. Herrin ................ herrin at dirtside.com bill at herrin.us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/> Falls
Church, VA 22042-3004
Hi Richard,
Could you run a bgp session on Router B ? I had to do this once for
a customer because we had layer 3 switches on the edge with routing. I
configured 2 BGP sessions at the customer's router. The first session was
between Customer C and Router B. I only sent the default route to the
customer. The next session was ebgp multihop between Router A and Customer
C with full routing. I did allow the customer to announce the /30 to
Router B just so Router A could learn the return path or you could just
static route the /30 from Router A
Now if the link Breaks between Router B and Customer C BGP will drop both
sessions.
Thanks
Jim Gonzalez
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