Cisco MDS 9000 Series Configuration Manual page 21

New and Changed Information
Slow Drain
Detection and
Congestion
Isolation
The new Congestion Isolation feature can detect a slow-drain
device via port monitor or manual configuration and isolate
it from other normally performing devices on an ISL. Once
the traffic to the slow-drain device is isolated, the traffic to
the rest of the normally behaving devices remain unaffected.
Traffic isolation is accomplished via the following three
features:
1. Extended Receiver Ready—This feature allows each ISL
between supporting switches to be split into four separate
virtual links, with each virtual link assigned its own
buffer-to-buffer credits. One virtual link is for control
traffic, one is for high-priority traffic, one is for slow
devices, and the remaining one is for normal traffic.
2. Congestion Isolation—This feature allows devices to be
categorized as slow by either configuration command or
by the port monitor.
3. Port monitor portguard action for Congestion
Isolation—Port monitor has a new portguard option to
allow the categorization of a device as slow, so that it can
have all the traffic flowing to the device routed to the
slow virtual link.
Cisco MDS 9000 Series Interfaces Configuration Guide, Release 8.x
Change Summary
8.1(1) Congestion
Detection,
Avoidance,
and
Isolation, on
page 129
3