OPERATIONAL DEFECT DATABASE
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When ifmgr is restarted (process restart ifmgr or crash restart) in the mid of an ISIS interface flap, the ISIS interface will be stuck at CLNS down state indefinitely and no ISIS adjacency formation is possible: show isis interface gigabitEthernet 0/0/0/1 GigabitEthernet0/0/0/1 Enabled Adjacency Formation: Disabled (CLNS I/O unavailable/down on the intf) show isis interface brief IS-IS 1 Interfaces Interface All Adjs Adj Topos Adv Topos CLNS MTU Prio OK L1 L2 Run/Cfg Run/Cfg L1 L2 ----------------- --- --------- --------- --------- ---- ---- -------- Gi0/0/0/1 No - - 0/2 0/2 Down 1497 - -
To hit this issue, the ISIS interface must be configured improperly. E.g. interface is not enabled for ipv6, but enabled under 'router isis interface address-family ipv6 unicast'. This can be confirmed via the 'All OK' column with 'No' in the output of show isis interface brief IS-IS 1 Interfaces Interface All Adjs Adj Topos Adv Topos CLNS MTU Prio OK L1 L2 Run/Cfg Run/Cfg L1 L2 ----------------- --- --------- --------- --------- ---- ---- -------- Gi0/0/0/1 No - 1 1/2 1/2 Up 1497 - -
Always configure the ISIS interface properly. E.g. if interface is not enabled for ipv6, do not configure 'router isis interface address-family ipv6 unicast'. This can be confirmed via the 'All OK' column with 'Yes' in the output of show isis interface brief IS-IS 1 Interfaces Interface All Adjs Adj Topos Adv Topos CLNS MTU Prio OK L1 L2 Run/Cfg Run/Cfg L1 L2 ----------------- --- --------- --------- --------- ---- ---- -------- Gi0/0/0/1 Yes - 1 1/2 1/2 Up 1497 - -
To recover after issue is hit, configure ISIS interface properly (see Workarounds) or perform a 'process restart isis'.
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