Author Archives: RedNectar Chris Welsh

Let me start with a picture.  Imagine a simple 2leaf/2spine topology with HostA attached to to Leaf1 and with HostB attached to to Leaf2. Enter IS-IS. The leaves and spines will exchange IS-IS routing updates with each other so that Leaf1 sees that it has two equally good paths to reach Leaf2, and Leaf2 sees that it has two equally good paths to reach Leaf1. Now think about the hosts. This is where COOP comes in. BGP is not needed until an external router is connected. Continue reading →