About collection of failure information on that ISIS neighbor cannot be set up.
If ISIS neighbor cannot set up, use the following commands to collect failure information for location of problem:
(1) display isis peer: displays the information on neighbor as to make sure if neighbor has been set up.
(2) display interface: displays the information related to interface as to make sure if MTUs of both interfaces are consistent.
(3) display cur conf isis: displays the relevant configurations of ISIS as to make sure if area address between neighbors are consistent.
(4) debug isis adjacency/debug isis sending-packet-content: displays the contents of hello packet of ISIS as to make sure if the hello packet transmitted by the peer contains the MAC address of local interface.