JAEN

Cisco IOS

shutdown / no shutdown

CautionDisable/enable a port

interface <if> → shutdown / no shutdown

Admin-down and up. The err-disabled recovery ritual is shutdown then no shutdown — on the right interface.

Examples

  • interface Gi1/0/12 shutdown no shutdownBounce a port
  • show interfaces status err-disabledPorts in err-disabled state and the reason
  • show errdisable recoveryCheck automatic recovery settings
  • errdisable recovery cause bpduguard errdisable recovery interval 300Auto-recover BPDU-guard ports after 300 seconds (config mode)
  • interface range Gi1/0/1 - 4 shutdownDisable several ports at once

Syntax

(config-if)# shutdown / no shutdown

Key points

  • If you no shutdown without removing the cause (bpduguard, psecure-violation and so on), the port drops again.
  • The Status column shows connected, notconnect, disabled (shut down) or err-disabled.
  • Save with copy running-config startup-config to keep the change after a reload.

When it does not work

  • Shutting down the wrong interface cuts unrelated traffic. Confirm the target with show run interface before you type shutdown.

Before you run it

Shutting an active port cuts traffic instantly.

Used when you see

Switch port won't come up
4
Bounce the port with shutdown / no shutdownFix the err-disable cause before bouncing.
See the whole flow →
Suspected L2 loop
4
Shut the offending port to restore serviceCut the suspect port first; investigate after.
See the whole flow →

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