Frame Relay WAN Slowness

[james.marshall]

We have a 256K WAN link that appears to be slow. As a test we sent a 8mb file from end-to-end which took 7 minutes. We tried different times of the day and it stayed around 7 minutes. I calculated that it should take about 1 minute. Stats from AT&T do not show over-utilization at either end. Are my calculations correct?

[noc]

yes.. 8MB file in 7 minutes is great on a 256k line.

perhaps you should run mrtg on the router closest

to you to determine real bandwidth / throughput and

your utilization of the link.

see www.mrtg.org

[faheyd]

Hmmm slow, maybe not. A 8MB (byte) file is 64,000,000 bits, or 64Mb (bits). 64Mb going across a 256Kbs link, in a perfect world with no overhead would take 250 seconds or 4.1 minutes. Well with packet/frame overhead, OS overhead, I/O on the computer and disk read/writes, a 7 minute download time really is great.

When you read a file size off a hard drive, it's usually in bytes (usually in 8 bit words).

[james.marshall]

Your calculations look correct and I don't know how I came up with 1 minute. Thanks.

[james.marshall]

We tried another transfer using a 1.8mb file. It took 5 minutes 15 seconds. In a perfect world I figured it would take 57 seconds. We then tried another transfer on a 973kb file and it took 2 minutes 26 seconds (perfect world: 30 seconds). It appears the transfer time is 5 times the perfect world transfer time. Is this normal overhead on transfers?