connections utilized through the network are not set to Jumbo, performance can degrade
significantly.
•
In addition to support for Jumbo frames, you can select
other
and configure the MTU size
between 1000 and 9000 bytes.
NOTE:
Jumbo frames are not supported for use with HP Continuous Access.
Compression
The MPX200 integrates a software compression option. This option can be set to
disable
,
enable
, or
auto
. When set to
auto
, the MPX200 continually assesses data compressibility and
automatically enables or disables compression based on data compressibility. The default setting
for software compression is
disable
for new installations. If upgrading from an version of firmware
earlier than v3.2.0.1, the existing setting is maintained (either
enable
or
disable
).
NOTE:
The auto compression mode setting is available with MPX200 firmware version 3.2.0.1
or later.
•
Use the
disable
setting if you know that the data being transferred over FCIP is not
compressible.
•
Use the
disable
setting when using a high speed WAN link (622 Mb/s OC-12 up to 1
Gb/s) in a configuration with simultaneous FCIP and iSCSI functions operating on the same
MPX200 blade.
•
Use the
enable
setting if you know that the data being transferred over FCIP is compressible.
•
Use the
auto
setting if you are unsure of data compressibility.
NOTE:
All mode settings require the proper setting of the MPX200 bandwidth per route
parameter, matched to the guaranteed available bandwidth (QoS) of the WAN link, based
on the number of routes. See
“Bandwidth per route” (page 122)
. HP does not recommend that
you use the
auto
setting if the available bandwidth per route is inconsistent or unpredictable.
TCP window size/scaling performance tuning
The MPX200 FCIP performance is maximized when properly configured. Knowing the RTT (distance)
between MPX200 Multifunction Routers and the WAN dedicated or guaranteed bandwidth allows
the gateways to be tuned for optimal performance. See
“Modifying the window size and scaling
factor” (page 123)
.
Modifying the window size and scaling factor
The MPX200 window size can be set to a maximum of 32 KB. The scaling factor is used as a
multiplier to increase the window size above 32 KB. Modify the window size and scaling factor
in the MPX200 Multifunction Router pairs based on the WAN RTT and link speed. To determine
the appropriate window size setting and scaling factor, use the pre-populated tables or the following
formula. In version 3.4.0.0 and above the TCP Window size and Window scaling factor were
combined into a single parameter that reflects the true TCP Window size versus the three parameters
used in previous versions.
NOTE:
Use the MPX200 CLI command
ping
to determine the RTT and select only the default
(~56) packet size for this test. For troubleshooting link issues, always use the maximum packet
size.
If the recommended TCP window size and scale factor for a given RTT and WAN link speed is
not shown in
Table 22 (page 124)
through
Table 28 (page 126)
, use the formula:
(RTT (ms) x
link rate (Kb/s) x (1 byte/8 bits)) = minimum window size (MWS).
IP performance tuning
123
