To manage the TCP
window size in Kbps, use the
tcp
maximum-bandwidth-kbps command. Use the
no form of this
command to disable this feature or revert to its factory defaults.
tcp max-bandwidth-kbps bandwidth min-available-bandwidth-kbps threshold {round-trip-time-ms milliseconds | round-trip-time-us microseconds}
no tcp max-bandwidth-kbps bandwidth min-available-bandwidth-kbps threshold {round-trip-time-ms milliseconds | round-trip-time-us microseconds}
Syntax Description
|
bandwidth
|
Specifies
the Kbps bandwidth. The range is 1000 to 1000000.
|
|
min-available-bandwidth-kbps
|
Configures the minimum slow start threshold.
|
|
threshold
|
Specifies
the Kbps threshold. The range is 1000 to 1000000.
For
Cisco MDS 9250i Multiservice Fabric Switch, the range is 1000 to 10000000.
|
|
round-trip-time-ms
milliseconds
|
Configures the estimated round-trip time across the IP network to reach the
FCIP peer end point in milliseconds. The range is 0 to 300.
|
|
round-trip-time-us
microeconds
|
Configures the estimated round-trip time across the IP network to reach the
FCIP peer end point in microseconds. The range is 0 to 300000.
|
Command Default
Enabled.
The FCIP defaults
are
max-bandwidth
= 1G,
min-available-bandwidth = 500 Mbps, and
round-trip-time
=1 ms.
The iSCSI defaults
are
max-bandwidth
= 10000 Mbps (10Gbps),
min-available-bandwidth = 8000 Mbps, and
round-trip-time
=1 ms.
Command Modes
FCIP profile configuration submode.
iSCSI interface configuration submode
Command History
|
Release
|
Modification
|
|
1.1(1)
|
This
command was introduced.
|
|
6.2(5)
|
The
IPStorage support was increased to 10G on the Cisco MDS 9250i Multiservice
Fabric Switch.
|
|
6.2(13)
|
The
maximum bandwidth of iSCSI was increased to 10G.
|
Usage Guidelines
The
maximum-bandwidth option and the
round-trip-time option together determine the
window size.
The
minimum-available-bandwidth
option and the
round-trip-time option together determine the
threshold below which TCP aggressively increases its size. After it reaches the
threshold the software uses standard TCP rules to reach the maximum available
bandwidth.
When configuring
tcp bandwidth using the
tcp
maximum-bandwidth-kbps and
tcp
minimum-bandwidth-kbps commands, the value should not exceed the
maximum speed of the physical IPStorage port.
The maximum and
minimum tcp bandwidth of all the FCIP and iSCSI interfaces that are using a
specific Gigabit Ethernet or IPStorage port should not exceed the maximum speed
of the physical IPStorage port.
For optimal
performance the minimum-bandwidth-kbps should be 80%-90% of the
maximum-bandwidth-kbps.
Examples
The following
example configures a FCIP profile:
switch# config terminal
switch(config)# fcip profile 5
switch(config-profile)#
The following
example configures the maximum available bandwidth at 900 Kbps, the minimum
slow start threshold as 300 Kbps, and the round trip time as 10 milliseconds:
switch(config-profile)# tcp max-bandwidth-kbps 900 min-available-bandwidth-kbps 300 round-trip-time-ms 10
The following
example reverts to the factory defaults:
switch(config-profile)# no tcp max-bandwidth-kbps 900 min-available-bandwidth-kbps 300 round-trip-time-ms 10
The following
example configures the maximum available bandwidth at 2000 Kbps, the minimum
slow start threshold as 2000 Kbps, and the round trip time as 200 microseconds:
switch(config-profile)# tcp max-bandwidth-kbps 2000 min-available-bandwidth-kbps 2000 round-trip-time-us 200
The following
example configures an iSCSI profile:
switch# configure terminal
switch(config)# interface iscsi 1/1-2
switch(config-if)#
The following
example configures the maximum available bandwidth at 9000000 Kbps, the minimum
slow start threshold as 8000000 Kbps, and the round trip time as 20
milliseconds:
switch(config-if)# tcp max-bandwidth-kbps 9000000 min-available-bandwidth-kbps 8000000
round-trip-time-ms 20
The following
example configures the maximum available bandwidth at 9000000 Kbps, the minimum
slow start threshold as 8000000 Kbps, and the round trip time as 20
milliseconds:
switch(config-if)# tcp max-bandwidth-kbps 9000000 min-available-bandwidth-kbps 8000000
round-trip-time-ms 20
The following
example reverts to the factory defaults:
switch(config-if)# no tcp max-bandwidth-kbps 10000000 min-available-bandwidth-kbps 8000000
round-trip-time-ms 20
The following
example configures the maximum available bandwidth at 5000000 Kbps, the minimum
slow start threshold as 4000000 Kbps, and the round trip time as 200
microseconds:
switch(config-if)# tcp max-bandwidth-kbps 5000000 min-available-bandwidth-kbps 4000000
round-trip-time-ms 200
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