Unanswered Question
Nov 17th, 2008


Question is my client is doing copy paste from US site location to asia site location the BW was upgraded from 3mbps to 20 mbps but when customer initiates file copy paste he wants to see the throughtput at 20mbps since he is paying for it but only gets like 3mbps or something

now the question is there a significant amount of delay involved in between two site how do we redules the RRT time (delay)? even when BW is 20mbps ?

any solution ?

QOS would not solve this as there is no congestion on link ?


I have this problem too.
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Jon Marshall Mon, 11/17/2008 - 08:53


Have a look at this recent thread which covers a very similiar issue -


As noted a lot of the issue will be to do with TCP acknowledgements/latency of the link etc. One other thing you may want to consider is a WAN acceleration device which can overcome so of the TCP issues.


MKCHAURASIA Mon, 11/17/2008 - 09:07

Thanks Jon

the link u sent me applies for genral (ftp) traffic

so help me understand this

for VOIP implementation site located far off delay tolerance required is less than 150ms so this delay is taken care of by simply configuring QOS right?

Jon Marshall Mon, 11/17/2008 - 10:10


Obviously there are physical limitations in terms of latency/delay but yes VOIP delay is generally taken care of with using QOS. Bear in mind VOIP uses UDP so the TCP latency is on the whole removed and also that obviously with FTP you are shifting a lot more data than with a VOIP call.

It's not simply a question of ensuring that VOIP has the available bandwidth but also that it doesn't get stuck behind larger less important packets in router queues/buffers.


Joseph W. Doherty Mon, 11/17/2008 - 10:21

There are several common causes for latency. One can be interface congestion, where QoS might help (e.g. VoIP). Another is network device processing latency. For the network device itself, and assuming it's not capacity related, a "faster" device can reduce such latency as can less network devices along the path. Lastly, there's distance latency. Electric signals do propagate at a fixed speed; not much you can do with this except use the shortest path. (This can be a very large or largest component of latency on a WAN.)


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