Silver Peak provides support for MTUs (Maximum Transmission Units) up to 9000 bytes. Because of pps (packets per second) limits on the LAN-side, using 9000-byte MTUs can lead to significant performance improvements in LAN-side throughput for applications such as storage replication.
More importantly, the appliances support interworking. You can configure 9000-byte MTUs on storage arrays even if the replication protocol is running over a WAN with standard (1500-byte) MTUs. This is important because not all service providers allow for jumbo frames on the WAN.
CAUTION 
Across all network devices, you must configure all interfaces on the same subnet to have the same MTU.
Across all network devices, you must configure all interfaces on the same subnet to have the same MTU. |
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For the Interface MTU, you must configure each pair of lan and wan interfaces on the appliance to have the same MTU value. For example, you’d configure both lan0 and wan0 to have a value of 9000 MTU. These are accessible via Configuration > Interfaces.
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To configure the tunnel MTU, access the Configuration - Tunnels page.
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If either end host has an MTU of 9000 and the tunnel MTU is 1500, then you need to disable the Adjust MSS to Tunnel MTU feature on both appliances. This prevents appliances from lowering higher MSS values negotiated by end stations to match the lower MTU of the tunnel.
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To disable this feature, go to the Optimization Policy, and in the TCP Accel Details column, click the icon to open the Advanced TCP Options.
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For more information, see “TCP Acceleration”, and check with Silver Peak Support, if necessary.