ISIS Query

Hi Rene,

I have a basic question in ISIS. Why we need to have IP addresses configured for interfaces though ISIS runs on OSI layer…? NSAP address will be not good enough…? generally we use NSAP to identify devices and if we want to carry any IP info we can carry over TLV’s. But why we need to have interfaces configured with IP’s…?


Hi Srini,

This is because of the next hop address. We use IP addresses as the next hop, not NSAP addresses. Without an IP address on the interface, we don’t have a next hop we can use.