-----Original Message----- From: William Herrin [mailto:bill@herrin.us] Sent: Monday, June 13, 2011 3:34 PM To: Richard Zheng Cc: nanog@nanog.org Subject: Re: bgp feed to customer On Mon, Jun 13, 2011 at 1:25 PM, Richard Zheng <rzheng@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@dirtside.com bill@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