|A1:||The difficulty with the internetwork of Figure 11.37, when running classful routing protocols on RTB, is that network 172.16.0.0 is variably subnetted. The solution is to use a 28-bit mask on RTB's E1 interface while RTC still uses a 27-bit mask for the same subnet. This solution works because 172.16.1.96 remains distinct in the internetwork of> Figure 11.37, whether it is subnetted with a 27-bit mask or a 28-bit mask.
RTB's configuration is:
interface Ethernet0 ip address 172.16.1.146 255.255.255.240!interface Ethernet1 ip address 172.16.1.98 255.255.255.240!router rip redistribute igrp 1 metric 1 passive-interface Ethernet0 network 172.16.0.0!router igrp 1 redistribute rip metric 10000 1000 255 1 1500 passive-interface Ethernet1 ...