Ethernet Example - Cisco Catalyst 2000 Configuration Handbook

60 Cisco LAN Switching Configuration Handbook
10. (Optional) Automatically reenable ports from the errDisable state.
a. Set the timeout period before ports are automatically reenabled:
b. Choose the causes that will automatically reenable ports:
By default, ports in the errDisable state are not automatically recovered or reenabled.
If automatic recovery is desired for an errDisable condition, use the errdisable
recovery cause command. The ports will be recovered after the errDisable timeout
period has expired. Choose one of the following reasons:
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11. Enable or disable the port:
(interface) shutdown
OR
(interface) no shutdown
By default, a port is enabled (enable or no shutdown). To disable the port, use the
disable or shutdown keywords.

Ethernet Example

A 10/100/1000 switch port connects a mail server. The port is set to 100 mbps, full
duplex. The port is also tuned for a single host so that there are no port startup delays
because of PAgP, STP, or trunk negotiations:
(interface) description Mail server
(interface) speed 100
(interface) duplex full
(global) errdisable recovery {interval interval}
If ports in errDisable are automatically reenabled, the ports remain in the
errDisable state for interval (30 to 86400 seconds, default 300 seconds).
(global) [no] errdisable recovery cause reason
BPDU Port Guard: A bridge protocol data unit (BPDU) is received on a port in
the STP PortFast state; use bpduguard.
UDLD: A unidirectional link is detected; use reason udld.
STP Root Guard: Use reason rootguard.
EtherChannel misconfiguration: The EtherChannel ports no longer have consis-
tent configurations; use reason pagp-flap.
Trunk negotiation flapping: Dynamic Trunking Protocol (DTP) is detecting
changes from one trunk encapsulation to another; use reason dtp-flap.
Port is going up and down: Use reason link-flap.
All known errDisable causes: Ports are put into errDisable if any problem from
this list is detected; use reason all.