Latency effect on TCP/IP throughput

[barconoida]

Dear All,

We currently have VPN tunnel accross a 1Mbps internet connection between 2 Loactions which are 400msec latency apart. On file transfer between locations we get not more then 400kbps speed. Is it limited due to latency figure. I refered to the below derivation of tcpip throughput which says :

Mathis, Semke, Mahdavi & Ott in Computer Communication Review, 27(3), July 1997, provides a short and useful formula for the upper bound on the transfer rate:

Rate <= (MSS/RTT)*(1 / sqrt{p})

where:

Rate: is the TCP transfer rate or throughput

MSS: is the maximum segment size (fixed for each Internet path, typically 1460 bytes)

RTT: is the round trip time (as measured by TCP)

p: is the packet loss rate.

By calculating with is on 0.5% packet drop and 400msce latency , throughput theoritically we cann't expect better than 400kbps levels.

Is it correct ? is there a way to incraese throughput on same network.

Rgds

RB

[smalkeric]

I feel there is some issue with the Link. Even if there is a latency the throughout will not be reduced by half. I think there is some physical layer issue. Do you see any errors that are increasing on the interface which is connected to the internet.?If the errors increasing then there is definitely a physical layer issue. You can try to give a continous ping to the remote end and check if you are getting drops.