Brocade Fabric Watch Administrator's Guide v6.2.0 (53-1001188-01, April 2009)

6 Fabric Watch Administrator’s Guide

53-1001188-01

Port fencing

A port that is consistently unstable can harm the responsiveness and stability of the entire fabric

and diminish the ability of the management platform to control and monitor the switches within the

fabric. Port Fencing is a Fabric Watch enhancement that takes the Port class, E_Port class,

F/FL_Port class, and Link Reset ports offline if the user-defined thresholds are exceeded.

NOTE

Port Fencing is not enabled by default. You must manually enable Port Fencing. Refer to Appendix

D, “Port fencing types” on page 93 for a complete set of port fencing types that are available in

M-EOS and Fabric OS v6.2.0.

When a port that has exceeded its user-defined thresholds is fenced by software, the port is placed

into the disabled state and held offline, thereby removing the port’s ability to transmit or receive

frames. After a port is disabled, user intervention is necessary for frame traffic to resume on the

port.

Active or online ports with Invalid Transmission Word (ITW) errors and CRC errors that exceed the

threshold are fenced after a six-second delay. In cases where two types of errors occur within the

six-second interval, the port is disabled and indicates the reason code for the first error type that

exceeded the threshold.

Port fencing and link reset monitoring

Link reset monitoring is used to recover from link timeout errors, when a port may not know the

status of the opposite port on the link. Large numbers of link resets indicate hardware problems,

which can be disruptive for the entire switch or fabric. To protect the switch and fabric from

experiencing fabric reconfiguration and traffic disruption caused by a single port, you can use port

fencing to fence off the port on which link resets exceed a specified threshold limit.

With port fencing, you can:

• Set threshold values for link reset errors.

• Configure alarms, boundary levels, and the threshold type for link reset errors.

Refer to “Configuring port fencing” on page 61 for instructions on how to configure port fencing.