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Errdisable port status

What are the main causes of a port going into the above state?

I have a small SAN solution, using a Cat 6509. On performing a test backup, the port associated with the client device went into errdisable mode after partially completing a job. The port is set auto speed/duplex.


Re: Errdisable port status

You probably have a duplex mismatch that caused enough errors that the switch errdisabled the port , or you may have a unidirectional link that shut off the port if you have this feature enabled .

Community Member

Re: Errdisable port status

Ensure your duplexing and so on is all set correctly, then use

set port enable mod/port

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Re: Errdisable port status

Causes of errDisable

At first, this feature was implemented to handle special collision situations where the switch detected excessive or late collisions on a port. Excessive collisions occur when a frame is dropped because of encountering 16 collisions in a row. Late collisions occur after every device on the wire should have recognized that the wire was in use. These types of errors could be caused by a cable that is not to specification (too long, wrong type, defective), a bad network interface card (NIC) card (with physical problems, or driver problems), or a port duplex misconfiguration. This last cause is common because of failures to negotiate the speed and duplex properly between two directly connected devices (for example, a NIC card connected to a switch). Only half-duplex connections should ever have collisions in a LAN; due to the Carrier-Sense Multi-Access (CSMA) nature of Ethernet, collisions are normal for half-duplex, as long as they do not exceed a small percentage of traffic.

As the capabilities of the CatOS grew, there were more ways that a port could become error-disabled. Some of these new ways included an EtherChannel misconfiguration, Bridge Protocol Data Unit (BPDU) port-guard violation, UDLD, and other (miscellaneous) causes.

The error-disable function allows the switch to shut down a port when it encounters any of these situations. Remember, a port being error-disabled is not by itself a cause for alarm, as long as one determines and resolves its root cause. An error-disabled port is a symptom of a deeper problem that must be resolved.

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