From: Jongsoo.Kim@Intelsat.com
Date: Fri Mar 25 2005 - 13:12:31 GMT-3
R1----ebgp---R2
R1---IGP-----R2
If you use R1's loopback address and R2's loopback adress for ebgp,
R1 and R2 will rely on IGP to reslove nexthop. SO far so good as IGP has
path on routing table.
Now if you announce R1's loopback address,
R2 will learn it as eBGP while R3 and R4 will learn it as iBGP.
This will cause a problem on R2 because eBGP AD will beat IGP AD.
You will see flapping on eBGP session because R2's bgp session will lose the
next-hop address leaned via IGP when eBGP overwrite.
Probably, what you need is to configure "network back-door" command in R2
for I think this will make eBGP AD for back-door network same as iBGP, which
can't beat IGP.
I don't see any issue of iBGP between R1 and R3.
You can just configure as usual because all you need is just a TCP session
for bgp.
HTH
Jongsoo
-----Original Message-----
From: ccie zeng [mailto:ccie.candidate@gmail.com]
Sent: Friday, 25 March, 2005 2:04 AM
To: ccielab@groupstudy.com
Subject: BGP Help
HI:
I have following topology:
R1---fr----R2---fr----R3----fr----R4
All routers running OSPF, R1&R2 area 5, R2&R3 area 1, R3&R4 area0.
Loopback address on every router can be reached by every router.
R3, R4 and R1 are in AS100(R3 does not have physcial connection to
R1), R2 in AS 65555, R1 can not peer with R4, R2 peered with R1 and
R3, they all peered with loopback address. advertise loopback address
of R1 into BGP. Could anyone tell me why I see "RIB Failure" for that
route on R3 and R4 in "show ip bgp"? Actually I am not quite sure how
to configure in this scenario where IBGP (R3 and R1) connection is
through EBGP connection.
Thanks
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