Why will BGP not advertise a default route?

[roger perkin]

I have a simple setup in my lab before implenting in production.

We have an MPLS WAN represented by R2

And a router each side of it representing the two sites with an Internet feed. R1 & R3

The default route is being redistributed into BGP on R1 and R2 from OSPF

My problem is that R3 has the default route but is not advertising it onto R2

R3#sh ip bgp

BGP table version is 9, local router ID is 172.31.144.254

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

              r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path

*> 0.0.0.0          10.250.251.193       20000             0 65001 i

R3#sh ip bgp neighbors 172.31.144.253 advertised-routes (Router 2)

BGP table version is 9, local router ID is 172.31.144.254

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

              r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path

*> 10.10.0.0/16    10.10.251.193       20000             0 65001 i

*> 10.20.0.0/16    10.20.251.193       20000             0 65001 i

Total number of prefixes 2

R3#

From the other side on R1 it works fine

If the default route is in the BGP RIB what are the reasons that it would not advertise it to R2?

R3 can ping the next hop back

[mfurnival]

This has tripped me up before - you need the "default-information originate" under the BGP statement on R3 or it will not advertise the default route. I think you can also do it with a network statement.

[antonio.guirado]

Be sure that 10.250.251.193 is in routing table of R2. BGP propagates the real next-hop of R3. So, R2 must

know how to go to 10.250.251.192. The simplest way is using IGP routing or the command "neighbor R2 next-hop-sef" in R3 but announces as next-hop itself to R2. Also, you can redistribute connected in R3.

Regards