Link flap & err-disabled problem in CISO IOS
Link Flap Problem :-
- Link flap means that the interface continually goes up and down.
- The interface is put into the err disabled state if it flaps more than five times in 10 seconds.
- The common cause of link flap is a Layer 1 issue such as a bad cable, duplex mismatch, or bad Gigabit Interface Converter (GBIC) card.
- Look at the console messages or the messages that were sent to the syslog server that state the reason for the port shutdown.
err-disabled problem :-
There are various reasons for the interface to go into err disable. The reason can be:
- Duplex mismatch
- Port channel miss-configuration
- BPDU guard violation
- Unidirectional Link Detection (UDLD) condition
- Late-collision detection
- Link-flap detection
- Security violation
- Port Aggregation Protocol (PAgP) flap
- Layer 2 Tunneling Protocol (L2TP) guard
- DHCP snooping rate-limit
- Incorrect GBIC / Small Form-Factor Plug-gable (SFP) module or cable
- Address Resolution Protocol (ARP) inspection
- Inline power