Compression, Tcp window size/scaling performance tuning, Modifying the window size and scaling factor – HP IP Distance Gateway User Manual
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NOTE:
Jumbo frames are not supported for use with HP P9000 or P6000 Continuous Access.
•
Other: Allows you to configure the MTU size to a value between 1000 and 9000 bytes.
Encryption products on the WAN link often add some number of additional bytes to each
packet, so it may be necessary to decrease the mpx110 MTU size setting to between 1450
and 1200. This accommodates the additional bytes, while maintaining a total MTU size of
1500 or less. Keeping the total MTU size to a maximum of 1500 ensures a single Fibre
Channel frame (2112 bytes) will fit within two Ethernet packets, resulting in optimal
performance.
Compression
The mpx110 integrates a software compression option. Enable compression for IP fabrics with an
RTT greater than or equal to 50 ms, or guaranteed WAN bandwidth of less than or equal to 45
Mb/s. See
TCP window size recommendations (page 28)
for compression options for specific
network rates and RTT.
TCP window size/scaling performance tuning
The mpx110 performance is maximized when properly configured. Knowing the RTT (distance)
between mpx110 gateways and the WAN effective data rate (connection type) allows the gateways
to be tuned for optimal performance. See
.
Modifying the window size and scaling factor
The mpx110 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 mpx110 gateway pairs based on the WAN RTT and link speed. To determine the appropriate
window size setting, use the pre-populated tables or a formula.
If the recommended TCP window size scale factor for a given RTT and WAN link speed is not
shown in
through
, use the following formula:
(RTT (ms) x link rate (Kb/s) x (1 byte/8 bits) = minimum window size (MWS)
Then, convert the MWS to a recommended scale factor by dividing it by the default window size
(32,768 bytes). Use
to determine the scale factor.
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Configuration rules and guidelines