Nuts and Bolts
Routes and Metrics
- IS-IS base spec used 6-bit metrics on links
- Allowed an uninteresting SPF optimization (CPUs are fast these days)
- Proved difficult to assign meaningful metrics in large networks
- Wide metric extension addresses this
- Dual IS-IS spec advertises only default into L1 areas
- Interarea traffic routed suboptimally
- Route leaking extension addresses this