WAN accelerator

[naitikpatel]

I want to knw what is  WAN accelerator.and wht the function it done in network ?

[Bilal Nawaz]

A WAN accelerator is an appliance that optimizes bandwidth to improve the end user's experience on a wide area network (WAN) or even LAN in bizarre cases.

The appliance, which can be a physical hardware component, software program, or an appliance running in a virtualized environment, speeds up the time it takes for information to flow back and forth across the WAN by using compression and data de-duplication techniques to reduce the amount of data that needs to be transmitted.
Simply, an accelerator works by caching duplicate files or parts of files so they can be referenced instead of having to be sent across the WAN again.

Take a look at Wiki's definition of WAN optimization:

http://en.wikipedia.org/wiki/WAN_optimization

According to Gartner report, Riverbed are leaders in this market:

Hope this helps

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[Edwin Summers]

An addition to Bilal's great info.

Remember that TCP is a "connection-oriented" protocol. It requires the destination to "acknowledge" packets so the sender knows what has been received. The sender waits for an acknowledgment after sending a certain number of bytes, called the "window".

ON a LAN, this typically happens quickly. But consider a long-distance link like a satellite hop. The one-way latency can be 250ms or more. Doesn't sound like much but it becomes the dominant factor determining throughput on the link. After each window of data, it takes half a second to get the ACK. That is just physics...it takes that long to get the signal from point A to B.

WAN optimizers work by "proxying" the connection. An optimizer is on each side of the connection close to the client and server.For the client, the local optimizer pretends to be the server (and vice versa). this allows the optimizer to quickly send ACKs and allow the conversation to happen quickly (the client and server get the ACKs at LAN -like speed rather than having to wait).

Now between the optimizers we still have the problem of latency, but they are programmed to handle this. Their TCP stacks are tuned specifically for this scenario. The specific way they operate depends on the vendor implementation, but includes the optimization methods Bilal discussed.

So the purpose of the WAN optimizer is to quickly or efficiently transfer some TCP data over "long, fat networks" (LFNs aka elephants). Note they can't accelerate all data and types w ill depend on vendor implementation and features enabled.

HTH,
Ed


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[paul driver]

+ 5 points bial & Ed
I have only ever used these once and everytime i am asked about them i always forger the name Ruverbed¡

Res
Paul

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