O'Reilly logo

IP Routing Primer by Robert Wright

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

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 ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required