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TCP optimization over satelite link with encryption

There's two WAN nodes on cisco 28xx and 871 with 2 satelite hops between them. Link throughput is 64Kb/sec. Encryption with IPSec tunnel applied between routers. TCP sessions in such a scheme are very slow and applications goes timed out. All my tries of RBSCP tunnel with IPSec encription between routers gave me no success.

Have anyone here real experience of implementing encrypted traffic transmition over slow satelite links?

Where should I look for a solution? Try RBSCP over IPSec harder? Try WAAS or Juniper WX or others?

I have nothing against Juniper but would it work good?


Re: TCP optimization over satelite link with encryption

The delay time increases the RTT at the end host and allows RBSCP time to retransmit lost TCP frames or other protocol frames. If the retransmission is successful, it prevents lost frame events from reaching the end host where congestion procedures would be enabled. In some cases the retransmission can be completed by RBSCP without inserting the delay. This option should be used only when the RTT of the satellite link is greater than 700 milliseconds.

New Member

Re: TCP optimization over satelite link with encryption

Yeah, you may have to look to WAN acceleration to make that work. I know that Riverbed Steelhead appliances work extremely well on satellite links. I have a good doc on the topic if you are interested. Just shoot me an email.

Justin Lofton

VP of Engineering

justinl @

Tredent Data Systems, Inc.

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