Internet----NE80-A-----NE80-B-----S8016----BAS, ISIS is operated between two NE80s. NE80-A works on level 2 and ISIS is run between NE80-B and S8016. S8016 works on level 1 and NE80-B on level-1-2. NE80-A is Internet egress and BAS attaches under S8016. Users under BAS cannot access network, but they can ping through S8016.
1. Check the transmission from S8016 to NE80-A and there is no problem. The link of each segment can be pinged.
2. Check route: S8016 has no default route pointing to NE80-B. NE80-B type is level-1-2 and can create default route and advertise it to S8016. Execute disp isis peer on NE80-B and it is found that neighbor relation is not built between NE80-B and S8016. Neighbor relation is only built between S8016 and NE80-A.
3. Check configuration: NET address fault of NE80-B and area address is not consistent with S8016's. Neighbor relation is not built and default route cannot be created. Change them as the same. S8016 can learn default route flooded by NE80-B and users under BAS can access network.
1. The transmission is problematic.
2. The route is problematic.
Whether level-1-2 router can create default route and flood it to level-1 router, one necessary condition is that the area address of level-1-2 router and level-1 router must be the same.