Displaying Credit Loss Recovery Actions - Cisco MDS 9000 Series Configuration Manual

Displaying Credit Loss Recovery Actions

frees the ingress buffers for frames of unrelated flows, thus reducing the latency of the frames through the
switch.
Note
• The no-credit frame timeout value should always be less than the congestion frame timeout for the same
• The slow-port monitor delay value should always be less than the no-credit frame timeout value for the
On 16-Gbps and later modules and systems, the no-credit timeout value can be 1 to 500 ms in multiples of 1
ms. Dropping starts immediately after the no-credit condition comes into existence for the configured timeout
value.
To configure the no-credit timeout value, perform these steps:
Step 1 Enter configuration mode:
switch# configure terminal
Step 2
Specify the no-credit timeout value:
switch(config)# system timeout no-credit-drop milliseconds logical-type edge
(Optional) Revert to the default no-credit timeout value (500 ms):
switch(config)# system timeout no-credit-drop default logical-type edge
(Optional) Disable the no-credit drop timeout value:
switch(config)# no system timeout no-credit-drop logical-type edge
Displaying Credit Loss Recovery Actions
When a port is at zero transmit credits for 1 full second (F ports) and 1.5 seconds (E ports), it is called a credit
loss condition. Cisco MDS initiates credit loss recovery by transmitting a Link Credit Reset (LCR). If the end
device responds with a Link Credit Reset Response (LCRR), the port is back at its fully agreed number of
B2B credits in both directions. If an LRR is not received, the port is shut down.
When the port detects the credit loss condition and recovers, some of the following actions might occur:
1. An SNMP trap with interface details can be sent, indicating the credit loss event.
2. The port can be error disabled.
3. The port can be flapped.
When the configured threshold is exceeded, one or more of these actions can be combined together. These
actions can be turned on or off depending on the situation. The Port Monitor feature provides the CLI to
configure the thresholds and action.
Cisco MDS 9000 Series Interfaces Configuration Guide, Release 8.x
176
port type, and the edge port frame timeout values should always be lower than the core port frame timeout
values.
same port type.
Congestion Detection, Avoidance, and Isolation