This has to be one of those so-obvious-I-just-can't-see-it problem.
Router R1 (AS 790) is fully peered with R2 (AS 300). R1 has two network statements configured under its BGP process, 172.31.5.0 and 172.31.6.0. These networks are NOT showing up anywhere in R2's routing table (not just not showing up as BGP routes, just plain not showing up).
Since these are loopback networks; could it be there's an unacceptable "NEXT_HOP" attribute, or what? WHAT STUPID THING AM I GETTING WRONG HERE...
Here's the relevant parts of R1's config
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interface Loopback5
ip address 172.31.5.1 255.255.255.0
!
interface Loopback6
ip address 172.31.6.1 255.255.255.0
!
router bgp 790
no synchronization
bgp log-neighbor-changes
network 172.31.5.0
network 172.31.6.0
neighbor 172.31.1.6 remote-as 300
no auto-summary
!
R1#sh ip bgp summ
BGP router identifier 222.1.1.1, local AS number 790
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
172.31.1.6 4 300 20 23 1 0 0 00:01:37 0
R1#
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And relevant output from R2:
====================================
R2>sh ip bgp sum
BGP router identifier 222.1.5.1, local AS number 300
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
172.31.1.5 4 790 24 21 1 0 0 00:02:06 0
R2>sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
U - per-user static route, o - ODR
Gateway of last resort is not set
C 222.1.5.0/24 is directly connected, Loopback0
172.31.0.0/16 is variably subnetted, 4 subnets, 2 masks
C 172.31.1.4/30 is directly connected, Serial0
C 172.31.1.5/32 is directly connected, Serial0
C 172.31.1.8/30 is directly connected, Serial1
C 172.31.1.9/32 is directly connected, Serial1
R2>sh ip bgp
R2>
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Thanks everyone. I look forward to being conked on the head with a saucepan and having something really obvious pointed out to me...
