Information Technology Reference
In-Depth Information
Example 5-18
R4 Load-Balancing Between R5 and R7 (Continued)
65102
172.17.2.2 from 172.17.2.2 (172.16.7.1)
Origin IGP, metric 0, localpref 100, valid, external, multipath, best
65102
172.17.2.1 from 172.17.2.1 (172.16.5.1)
Origin IGP, metric 0, localpref 100, valid, external, multipath
multipath, best
multipath
Example 5-19
R6 Load-Balancing Between R5 and R7
R6#show ip bgp 10.2.0.0
BGP routing table entry for 10.2.0.0/16, version 11
Paths: (3 available, best #1, table Default-IP-Routing-Table)
Advertised to peer-groups:
internal
Advertised to non peer-group peers:
172.17.2.1
65102
172.17.2.2 from 172.17.2.2 (172.16.7.1)
Origin IGP, metric 0, localpref 100, valid, external, multipath, best
65102
172.16.4.1 (metric 409600) from 172.16.4.1 (172.16.4.1)
Origin IGP, metric 0, localpref 100, valid, internal
65102
172.17.2.1 from 172.17.2.1 (172.16.5.1)
Origin IGP, metric 0, localpref 100, valid, external, multipath
multipath, best
multipath
The routers R4 and R6 advertise the prefix 10.2.0.0/16 via iBGP to the routers R3, R8, R9,
and R11. The path selection on these routers is based on the IGP metric to the next-hop
addresses, which are the loopback interfaces on R4 and R6. When the IGP metric is equal,
the path selection is based on the lowest router ID.
The path-selection process in the regional border routers varies depending on the redundancy
in that region, as shown in Figure 5-12.
In AS 65104, R12 receives only a single path for 10.2.0.0/16. Figure 5-13 shows the topol-
ogy for the DMZ between AS 65104 and AS 65100. The result is that R12 installs the path
received from R11 for 10.2.0.0/16.
