The SD-WAN Optimization Settings offers various levels of Compression, Deduplication, Packet Loss Recovery and Forward Error Correction levels as well as Peer timeout, Global WAN Tx Rate, TCP Acceleration and Webcache.
IPComp encapsulation is the most efficient and configured as the default setting. UDP encapsulation can be used strategically where it is not possible to configure Firewalls to allow IPComp. UDP encapsulation may also be required in certain NAT scenarios. UDP Encapsulation is required for Tunnel Mode and adds 28 bytes overhead per packet.
A peer becomes idle after a certain period of time. Traffic switches to bypass traffic during the idle period. Peers detect each other through TCP Option 76. Start a new TCP session to bring the peers online. The default peer timeout value is 60 seconds.
Global Wan Tx Rate
This is a shaper to limit all WAN Outbound traffic to a specified limit. The limit should be equal to the WAN upstream speed. This setting is required to ensure optimal Packet Loss Recovery operation. Default setting is 0 (disabled) and the value is defined in kilobits per second (kbps).
0 – Disable
1 – Low compression level, high throughput
8 to 12 – Best results
20 – High compression level, low throughput
This value sets the stream compression. Compression level ranges from 1 to 20. Higher compression leads to lower max throughput and lower compression leads to higher max throughput but less compression ratios. Disable stream compression by setting the value to 0. The default compression level is 10.
Level 4 is the recommended setting and provides deduplication at the highest level and is used in most scenarios. Level 1 is recommended for high speed or limited resources scenarios. Level 0 can be used disable Deduplication Compression, while still processing Deduplication Decompression. Deduplication on level 0 on both ends of a WAN link will disable deduplication completely. This can be used in high speed or low resources scenarios or part of a Point-to-Multipoint design.
Packet Loss Recovery (PLR)
The level indicates the aggressiveness of the loss recovery. Higher levels means the algorithm will wait less time before declaring that packets have been lost. Level 2 is the default and recommended setting for most scenarios. Levels can be increased for higher latency links.
Forward Error Correction (FEC)
When Forward Error Correction is enabled, a special parity packet is sent for every group of 5, 10 or 20 packets. When a packet is lost in the group, the parity packet is used to reconstruct the missing packet. More information can be found in Forward Error Correction article.
This global setting enables or disables the TCP Accelerator. The default setting is disabled. When TCP-x is enabled on default settings, all TCP sessions are processed by the TCP Accelerator performance enhancing proxy. See the TCP Accelerator for more configuration options.
Webcache is a feature available to cache and accelerate web content. It is disabled by default. For more information, refer to the Webcache article.