-----Original Message----- From: William Herrin [mailto:b...@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 <rzh...@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 ................ her...@dirtside.com b...@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
