Cisco MDS 9000 Series Configuration Manual page 170

Information About Congestion Detection
• Slowport monitor (Fibre Channel only)—A threshold value of slowport monitor is specified to detect
ports that are at zero transmit credits for a specified continuous duration. When a port is at zero Tx credits
continuously for the specified threshold value, the switch records an entry in the slowport-monitor log
and in logging onboard. This entry is shown in the show process creditmon slowport-monitor-events
and show logging onboard slowport-monitor-events commands. The entry that is shown in the outputs
of these commands is identical, except that the slowport-monitor log only holds the last ten events per
port. However, the logging onboard holds the events in chronological order and can hold more events
when compared to the slowport-monitor log.
Events are recorded at a maximum frequency of 100 ms. When the count goes up, operational delay is
displayed in the command output. Operational delay indicates the length of time when the port was at
zero Tx credits. If the count goes up by more than one from the previous entry, then the operational delay
is the average operational delay from multiple events.
In the following example, at 02/02/18 18:12:37.308 the slowport detection count was 276 and the previous
value was 273. This example indicates that there were three intervals of time in the previous 100 ms
where the port was at zero Tx credits for 1 ms or more. The average time the port was at zero credits is
shown in the oper delay column (4 ms). Oper delay of 4 ms indicates that there was a total of 12 ms of
time when the port was at zero Tx credits in the previous 100 ms. The 12-ms duration was in three
separate intervals.
Port monitor can also generate a slowport-monitor alert. By default, slowport-monitor alert is set to off.
Slowport-monitor must be configured to get the port-monitor slowport-monitor alerts.
The show process creditmon slowport-monitor-events [module number] [port number] command
shows the last ten events per port.
Cisco MDS 9000 Series Interfaces Configuration Guide, Release 8.x
152
TX
326283313 unicast packets 105258 multicast packets 0 broadcast packets
...snip
0 Tx pause
The following example displays the RxPause, TxPause, RxWait, and TxWait for Ethernet ports
used for FCoE:
switch# show interface priority-flow-control
RxPause: No. of pause frames received
TxPause: No. of pause frames transmitted
TxWait: Time in 2.5uSec a link is not transmitting data[received pause]
RxWait: Time in 2.5uSec a link is not receiving data[transmitted pause]
=============================================================================================================
Interface Admin Oper
TxWait-2.5us(sec))
==============================================================================================================
ethernet-
port-channel540 Auto
152866694355(382166)
Ethernet2/1 Auto
5930346153(14825)
...snip
Ethernet2/48 Auto
Ethernet3/1 Auto
0(0)
...snip
Ethernet3/6 Auto
Ethernet3/7 Auto
0(0)
(VL bmap) VL RxPause
NA (8) 3 456200000
On (8) 3 4481929
Off
On (8) 3 0
Off
On (8) 3 0
Congestion Detection, Avoidance, and Isolation
TxPause RxWait-2.5us(sec)
0 0(0)
0 0(0)
0 0(0)
0 0(0)