Example 397 Interface Configuration with Secondary Addresses

interface Ethernet0 ip address 131.108.2.1 255.255.255.0 secondary ip address 131.108.1.1 255.255.255.0

If split horizon is enabled, this secondary address will not be advertised on EthernetO.

Similarly, imagine a situation in which there are three routers—Rl, R2, and R3—on the same Ethernet, as shown in Figure 3-35.

Figure 3-35. Another Split Horizon-Enabled Network Vulnerable to RIP

Problems

Figure 3-35. Another Split Horizon-Enabled Network Vulnerable to RIP

Problems

R1 and R3 are running OSPF. R1 and R2 are running RIP, as in the preceding example. Now, R3 advertises certain routes through OSPF to R1 that R1 must redistribute in RIP. R1 will not advertise those OSPF routes to R2 because of split horizon. The solution is again to disable split horizon.

Basically, these are the three main reasons for turning off split horizon. Any other situation might create a routing loop if split horizon is turned off.

Was this article helpful?

0 0

Post a comment