Information Technology Reference
In-Depth Information
The change made in this step is service-affecting on the router that originates prefixes. The
prefix 192.168.201.0/24 is temporarily unavailable during the configuration change. R4 can
be put back in the forwarding paths when all the routing information is learned correctly.
As demonstrated in the previous two case studies, resetting the BGP next hop to R1 for
confederation eBGP routes on the R1-R4 session can cause forwarding loops between the
core routers in this step. The loops are avoided when the next hop is reset for only the
external prefix on R1.
NOTE
Example 8-91 shows the BGP summary table on R4. The session with R7 is down, as
expected.
Example 8-91
BGP Summary Table on R4
R4#show ip bgp summary
BGP router identifier 192.168.100.4, local AS number 100
BGP table version is 5, main routing table version 5
4 network entries and 7 paths using 740 bytes of memory
4 BGP path attribute entries using 240 bytes of memory
3 BGP AS-PATH entries using 72 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 4/2 prefixes, 7/0 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
192.168.14.1 4 65000 21 27 5 0 0 00:06:44 3
192.168.24.2 4 65000 23 24 5 0 0 00:05:39 3
192.168.100.6 4 100 84 87 5 0 0 00:15:53 1
192.168.100.7 4 100 97 99 0 0 0 never Idle
Example 8-92 shows the BGP RIB on R4. The dual paths for prefixes from outside the local
AS are received from R1 and R2.
Example 8-92
BGP RIB on R4
R4#show ip bgp
BGP table version is 5, local router ID is 192.168.100.4
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure
Origin codes: i - IGP, e - EGP, ? - incomplete
continues
