Information Technology Reference
In-Depth Information
BGP Peering Summary for CLNS Peers
Example A-3
R3#show bgp nsap summary
BGP router identifier 10.1.1.3, local AS number 65100
BGP table version is 14, main routing table version 14
8 network entries and 8 paths using 1584 bytes of memory
4 BGP path attribute entries using 240 bytes of memory
2 BGP AS-PATH entries using 48 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP activity 23/22 prefixes, 24/16 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
10.1.1.2 4 65100 110 114 14 0 0 00:42:51 1
10.1.1.4 4 65100 116 116 14 0 0 00:41:49 3
10.1.1.5 4 65100 107 112 14 0 0 00:42:52 1
172.16.1.5 4 65101 118 131 14 0 0 00:42:33 2
The iBGP sessions between the core routers are all established, and the eBGP session with
R1 (peer 172.16.1.5) is also established. The eBGP session with R1 shows that at least one
UPDATE message has been received, which means that R3 should be originating informa-
tion in its L2 LSP for R1 to provide next-hop reachability. This is shown in Example A-4.
eBGP-Neighbor Route Based on ES-IS Adjacency
Example A-4
R3#show clns route
Codes: C - connected, S - static, d - DecnetIV
I - ISO-IGRP, i - IS-IS, e - ES-IS
B - BGP, b - eBGP-neighbor
b 47.1111.1111.1111.1111.00 [15/10]
via 1111.1111.1111, Serial3/0
Example A-4 shows only the relevant routing entry. The rest of the CLNS routing informa-
tion was removed for clarity. CLNS routes received by standard BGP are marked with a B.
The special eBGP-neighbor route that is injected into CLNS routing and the IS-IS L2 LSP
is shown with a b. This prefix appears only as an eBGP-neighbor route in the router that
terminates the eBGP session. This prefix appears as a normal IS-IS route in the rest of that
routing domain.
In this example, each aggregation autonomous system originates a prefix from the gateway
routers. In AS 65101, NSAP 47.1234 is originated, and in AS 65102, NSAP 47.5678 is
originated. Both of these NSAPs can be seen in the core router's BGP table, as shown in
Example A-5, taken from R5.
