S e n d d o c u m e n t a t i o n c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m
Configuring TCP Parameters
You can control TCP behavior in a switch by configuring the following TCP parameters.
When FCIP is sent over a WAN link, the default TCP settings may not be appropriate. In such cases, we
recommend that you tune the FCIP WAN link by modifying the TCP parameters (specifically bandwidth,
round-trip times, and CWM burst size).
This section includes the following topics:
Minimum Retransmit Timeout
You can control the minimum amount of time TCP waits before retransmitting. By default, this value is
200 milliseconds (msec).
To configure the minimum retransmit time, follow these steps:
switch(config-profile)# no tcp
You can configure the interval that the TCP connection uses to verify that the FCIP link is functioning.
This ensures that an FCIP link failure is detected quickly even when there is no traffic.
If the TCP connection is idle for more than the specified time, then keepalive timeout packets are sent
to ensure that the connection is active. This command can be used to tune the time taken to detect FCIP
You can configure the first interval during which the connection is idle (the default is 60 seconds). When
the connection is idle for the configured interval, eight keepalive probes are sent at 1-second intervals.
If no response is received for these eight probes and the connection remains idle throughout, that FCIP
link is automatically closed.
Only the first interval (during which the connection is idle) can be changed.
OL-16184-01, Cisco MDS SAN-OS Release 3.x
Minimum Retransmit Timeout, page 40-13
Keepalive Timeout, page 40-13
Maximum Retransmissions, page 40-14
Path MTUs, page 40-14
Selective Acknowledgments, page 40-14
Window Management, page 40-15
Monitoring Congestion, page 40-15
Estimating Maximum Jitter, page 40-16
Buffer Size, page 40-17
Specifies the minimum TCP retransmit time for the TCP
connection to be 500 msec. The default is 200 msec and the
range is from 200 to 5000 msec.
Reverts the minimum TCP retransmit time to the factory
default of 200 msec.
Cisco MDS 9000 Family CLI Configuration Guide