High Response Time

[kanwar]

HI,

we have a T1 to Japan and the response time is very high. My understanding was that all T1's should have the same response time. help is apperciated.

Thanks in advance

[ahmed-hussein]

Hello,

High response time due to may resons, like congestion, you can monitor the rate on the link to identify the cause of the problem

may be also due to layer 1 problem.

Thanks,

Ahmed Hussein

[kanwar]

Thanks for the response. I was told by the Provider that this is the nomal response time they to Japan. would this be normal as we are running VOIP. I was under the impression that all T1 should have the same respose time. we had vpn to Japan and was the same reposne time if not better. any thoughts ?

Thanks for all your help

Kaiser A

[mheusinger]

Hello,

the speed of light in a medium is constant (A. Einstein). Electrical signals travel with max. the speed of light in this medium. Thus more miles means more delay. With 100000 km/s (speed in copper) and lets say 20000 km one way, i.e. 40000 km signal travelling distance you would at least expect 400 ms delay. Less distance gives less delay.

Hope this helps! Please rate all posts.

Regards, Martin

[pciaccio]

You have to understand that from the US to Japan you are talking about approx. 12,500 miles each way. If you quesstemate about 10ms per 1000 miles you are talking about over 1 second each way. A turn around of over 2 secs for round trip data...

[kanwar]

how would you support voice traffic over a WAN. per Cisco desirable response should be under 150 msec.should we implement LLQ or RTP compression?

Thanks

[mheusinger]

Hello,

150 ms is the ITU recommended (G.114) one-way delay, so 300 ms round trip time. Unfortunately you have to spend some time for other VoIP related things - coder delay, packetization delay, dejitter buffer. It is also stated, that larger one-way delays might be acceptable, as long as users are aware of it. As far as I remember they state something like up to 400 ms.

So LLQ is a must, RTP header compression might help, but not too much with respect to your delay issue.

Hope this helps! Please rate all posts.

Regards, Martin

[kanwar]

Thanks to everyone for all the help. It was very helpful.