Re: Simulating network latency in a testbed

Jeff Paige wrote:
>
> I am trying to do an analysis of network latency requirements for a
> set of Oracle-based client/server applications which will run over
> national and international WAN circuits (mostly frame-relay). Since we
> don't have good performance requirements data from the application
> developer, my organization is preparing to do some performance testing
> in a testbed environment. I am looking for a device which I could use
> to insert delays into an ethernet LAN segment between a local client and
> server. Ideally, this device would allow me to control the duration of
> delay inserted, so that I could simulate a wide range of WAN/LAN
> latencies. I am envisioning something as simple as an ethernet repeater
> with the ability to set a delay time between the input and output
> buffers.
>
> Any information on such a device, or an alternative method to simulate
> network latency in a testbed environment, would be greatly appreciated.
>
> Jeff Paige
> Eaton Corporation

What you probably want is a link simulator...try searching on that.

I've worked with T1 and T3 simulators that allow you to vary link speed and link latency (in either direction). Unfortunately, it's been a while and I can't remember any vendor names.

Another option is doing a packet level transaction benchmark in a LAN environment (this is the approach we use). Basically, you capture each transaction using a standard LAN protocol analyzer. Then you take the protocol trace and isolate how much of the delay is due to LAN latency and speed. Finally, you can extrapolate these results using typically WAN link speeds, link propagation delays, and estimated congestion delays.

-- 
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Lawrence Baldwin				baldwinl_at_mindspring.com
System Management Technologies, Inc.
--Internet Protocol Analysis Services
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