Cisco MDS 9000 Series Configuration Manual page 174

Information About Congestion Detection
Cisco MDS NX-OS 8.2(1) and later releases, the alerts are logged in OBFL and are displayed in the
show logging onboard datarate command.
• Port monitor (Fibre Channel only)—Port monitor can generate alerts for various congestion-related
counters. Port monitor has two thresholds that are called rising threshold and falling threshold. The rising
threshold is when the counter of a port reaches or exceeds the configured threshold value. The falling
threshold is when the counter of a port reaches or falls below a configured value. For each event, an alert
is generated. The time that the port was between the rising threshold and falling threshold is when the
event was occurring. These alerts are recorded in the RMON log in all releases.
Table 18: Features to Detect Slow Drain, on page 156
condition:
Table 18: Features to Detect Slow Drain
Feature Name
Port monitor's credit-loss-reco
counter
Port monitor's invalid-crc counter
Port monitor's invalid-words counter
Port monitor's link-loss counter
Port monitor's lr-rx counter
Port monitor's lr-tx counter
Port monitor's rx-datarate counter
Port monitor's signal-loss counter
Port monitor's state-change counter
Port monitor's sync-loss counter
Port monitor's tx-credit-not-available
counter
Port monitor's timeout-discards
counter
Cisco MDS 9000 Series Interfaces Configuration Guide, Release 8.x
156
Congestion Detection, Avoidance, and Isolation
describes the features that help detect the slow-drain
Description
Credit-loss-reco counter resets a link when there is not enough
transmit credits available for 1 second for edge ports and 1.5
seconds for core ports.
Invalid-crc counter represents the total number of CRC errors that
a port receives.
Invalid-words counter represents the total number of invalid words
that a port receives.
Link-loss counter represents the total number of link failures that
a port encounters.
Lr-rx counter represents the total number of link reset primitive
sequences that a port receives.
Lr-tx counter represents the total number of link reset primitive
sequences that a port transmits.
Rx-datarate counter receives frame rates in bytes per seconds.
Signal-loss counter represents the number of times a port
encountered laser or signal loss.
State-change counter represents the number of times a port has
transitioned to an operational up state.
Sync-loss counter represents the number of times a port
experienced loss of synchronization in Rx.
Tx-credit-not-available counter increments by one if there are no
transmit buffer-to-buffer credits available for a duration of 100
ms.
Timeout-discards counter represents the total number of frames
that are dropped at egress due to congestion timeout or
no-credit-drop timeout.