Describe the difference between an OSPF and IS-IS backbone.
OSPF has a backbone area or area O. All nonzero areas must be connected to the backbone through a router or a virtual link. IS-IS has a backbone area made up ofa contiguous chain of Level 2 capable routers.
In IS-IS, what does Level 1 routing mean?
Level 1 routing is routing between destinations in the same IS-IS area.
What is the OSPF counterpart to Level l routing?
Intra-area routing.
In IS-IS, what is the function of a Level 1-2 router?
A Level 1-2 router has two IS-IS databases. The Level l database is used for routing to destinations within the router's configured area. The Level 2 database is used to route between destinations in different areas.
What is the OSPF counterpart to a Level 1-2 IS-IS router?
An Area Border Router (ABR).