Understanding the Role of Split Horizon
Split horizon is the function of not advertising routes over an interface that the router is using to reach the route. The role of split horizon is to help avoid routing loops in a network. Split horizon prevents a router from advertising routes in its routing table that are known via a particular interface back out that same interface. This scenario explains how turning off split horizon can lead to routing loops.
Refer to Figure 2-6. RouterA would not advertise 168.71.8.0 to RouterC over serial 1 because RouterA learned about this subnet from RouterC over its serial 1 interface. However, RouterA does send and receive updates for 168.71.8.0 over serial 0 because RouterB is not the router that RouterA ...
Get IP Routing Primer now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
