366 Chapter 6: Routing
Issues When Multiple Routes to the Same Subnet Exist
The first issue is straightforward and is described more easily with the example in Figure 6-4
and Tables 6-6 and 6-7.
Figure 6-4
Routers A and C Advertising to Router B
NOTE
The routing updates in Figure 6-4 show only the information needed for the point being made
in this example; other routes that would normally be in the routing update are omitted.
Table 6-6
Router B Routing Table, with Two Routes to Same Subnet While Router B Serial 1 Is Down
Group
Outgoing Interface
Next Router
Metric
162.11.5.0
S0
162.11.8.1
1
162.11.7.0
E0
0
162.11.8.0
S0
0
162.11.9.0
S0
162.11.8.1
1
162.11.10.0
S0
162.11.8.1
2
Router A
Router C
162.11.9.0
162.11.5.0
162.11.10.0
162.11.7.0
162.11.10.0
Routing Update
162.11.5.0
2
1
162.11.9.0
1
162.11.8.0
Router B
S1
S0
S0
S0
S1
S1
E0
162.11.10.0
Routing Update
162.11.9.0
1
1
162.11.5.0
2
1
2
162.11.6.0
ch06.fm Page 366 Monday, March 20, 2000 5:11 PM