Objectives
The simulator ticks each one as soon as the network meets it.
Start IS-IS on R1, R2 and R3 with NET 49.0001.0000.0000.000X.00 (X = router number).
Make every router Level-2 only (is-type level-2-only).
Enable IS-IS on the two core links (ip router isis).
Advertise each Loopback0 without sending hellos on it (passive-interface Loopback0).
Run show isis neighbors on R2: R1 and R3 must be L2 neighbors.
From R1, ping 3.3.3.3, which R1 learns as an i L2 route.
Before you start
A NET is area + 6-byte system ID + 00, for example 49.0001.0000.0000.0001.00. IS-IS runs per interface, so the network statements of OSPF have no IS-IS equivalent. A passive interface is advertised but sends no hellos. IS-IS routes have administrative distance 115.
Concept
IS-IS levels and the ATT default route
IS-IS is the link-state protocol most providers run in their core. Routers are identified by a NET such as 49.0001.0000.0000.0001.00 (area, system ID, selector). Level 1 routes within an area, Level 2 between areas, and Level 1-2 routers join the two.
