Information Technology Reference
In-Depth Information
Example 8-11 shows the BGP RIB on R7. Note that all four prefixes are available. Note the
next hops for all the prefixes.
Example 8-11
BGP RIB on R7
R7#show ip bgp
BGP table version is 5, local router ID is 192.168.100.7
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>i172.16.0.0 192.168.100.1 0 100 0 200 i
*>i192.168.200.0 192.168.100.3 0 100 0 i
*>i192.168.201.0 192.168.100.6 0 100 0 i
*> 192.168.202.0 0.0.0.0 0 32768 i
Example 8-12 shows the BGP RIB on R8. The three prefixes from AS 100 are properly
installed.
Example 8-12
BGP RIB on R8
R8#show ip bgp
BGP table version is 5, local router ID is 192.168.18.8
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 172.16.0.0 0.0.0.0 0 32768 i
*> 192.168.200.0 192.168.18.1 0 100 i
*> 192.168.201.0 192.168.18.1 0 100 i
*> 192.168.202.0 192.168.18.1 0 100 i
Migration Procedures
When migrating a fully meshed network to an RR-based network, first migrate routers that
are to become RRs, and then migrate client routers one at a time. When all the clients are
moved to the new RR, migrate the remaining core routers to RRs. This minimizes
downtime if access routers have redundant connections to the core.
NOTE
When access routers do not have redundant physical connections to the core, you should
create additional BGP sessions to avoid traffic loss, as indicated previously in the section
“Minimizing Traffic Loss.” This approach works when the BGP process is not going to be
replaced during the migration, as in this case study.
