ISIS establish conditions neighbor:
1. unusual one subnet and can not establish neighbor relations
[AR4]dis isis error
Unusa1le IP Addr : 13
2. Direct adjacent routers, system id not identical (similar to the OSPF router id)
Repeated System ID : 6
3. The error-area id of the area need only L1 router ID must be the same
Mismatched Area Addr(L1): 2
Silent 4.silent interface port
Do not configure the interface connected to the router does not send and receive hello packets
Typically disposed in the PC connection interface, it does not affect the routing advertisement
int g0/0/0
isis silent
5. certified, ISIS certification
6. The same type of network, ISIS supports two types of P2P networks and broadcast
Bad Circuit Type : 15
7. A router connected to the MTU of the interface must be the same
PPP link MTU of the interface 1500
Ethernet link MTU value of 1497, LLC 3byte
[AR3]dis isis int
Interface information for ISIS(1)
---------------------------------
Interface Id IPV4.State IPV6.State MTU Type DIS
Loop0 001 Up Down 1500 L1/L2 --
S4/0/1 002 Up Down 1500 L1/L2 --
GE0/0/1 001 Up Down 1497 L1/L2 Yes/No
GE0/0/1 001 Mtu:Dn/Lnk:Up/IP:Up Down 1397 L1/L2 No/No
[AR3]