Cisco Cisco MDS 9000 NX-OS Software Release 6.2 トラブルシューティングガイド

The Multilayer Data Switch (MDS) port-monitor function provides a way of alerting on various
conditions. Nine of these are applicable to situations where devices are causing congestion in the
Storage Area Network (SAN). The following are samples for policies to alert on slow drain
conditions. These should be considered starting points and not definitive. They can be tweaked for
individual needs.

For delta counters the counter must increase by the value configured in the rising-threshold polling
interval for a rising alert to trigger. When the delta value lowers to the falling-threshold in the
polling internal then a falling threshold alert is generted.

The following are descriptions of the counters included in the policy:

lr-rx
Number of times a Link Reset(LR) was received

lr-tx
Number of times a Link Reset(LR) was transmitted(lr-tx)
Similar to credit-loss-reco counter

credit-loss-
Number of times credit loss recovery was initiated due to port at 0 Tx credits for 1/1.5 seconds
Most severe indication of congestion
Normally other counters like timeout-discards will also increment

timeout-discards
Number of packets dropped due to reaching the congestion-drop (timeout) threshold

tx-credit-not-available
Indicates 100ms intervals of a port at 0 Tx credits
rising-threshold is configured as a percentage of polling-interval(1 second)

tx-discards
The number of packets dropped at egress for a variety of reasons.
This counter would include timeout-drops as well

slowport-count
Counts the number of times the slowport-monitor threshold was reached