I have been working a project (day and night lately) where most of the communications links are contracted as T3 equivalents. I have recently been in a major disagreement with the vendor supplying the links over the actual bandwidth supplied.

I have been testing the bandwidth delivered by running a few simultaneous FTP

 

[QUOTE]Originally posted by cdelena
[B]I have been working a project (day and night lately) where most of the communications links are contracted as T3 equivalents. I have recently been in a major disagreement with the vendor supplying the links over the actual bandwidth supplied.

I have been testing the bandwidth delivered by running a few simultaneous FTP

 

keep in mind, a T3 is 45 MegaBITs a second, and ftp will give you MegaBYTEs a second.

so divide by 8. One T3 @ 100% utilization can transfer 5.625 MegaBytes/Second. Now achieving 100% in 1 direction is a hard thing to do. But you should be able to get 80-90% utilization w/ a couple ftp clients.

I would want to see ~4.5-5 MegaBytes/sec across a clear T3.

Hope this helps.

 

[QUOTE]Originally posted by krazik
[B]keep in mind, a T3 is 45 MegaBITs a second, and ftp will give you MegaBYTEs a second.

so divide by 8.

 

Thanks guys, I understand bits and bytes (some things have changed in 20 years, but that is pretty basic and I was a decent assembly language programmer in my day).

Yes, I only refer to BITS when dealing with transmission speeds.

The real question is what is FTP performance over a WAN. I accept that the rate will be affected by network latency, but to what amount? I expect to get an aggregate band width of about 45mb, but I am trying to gauge my test technique here.

Let me ask this in another way.. what is the highest rate of transmission you have ever seen from FTP over a WAN (LAN speeds don

 

CD, like you I've been in the industry 20+ years. It's been many years (10-15), however, since I have done this sort of stuff hands on and I'm an old SNA guy so IP networks still puzzle me a little.

What I can say, is that IN MY EXPERIENCE I have found that I can get very close to full bandwidth considering packet sizes and header / trailer overheads.

As an example, my 512kbit home cable service will give me down load speeds getting fairly close to 60kbytes/sec when transferring files under Napster. I would therefore expect you to get 90%+ of your rated speed even with multiple transfers.

Here in Oz we are now moving to a new service called Wideband IP which essentially provides LAN bridging using fibre/high speed copper between sites purchased in units of 10 Mbits bandwidth. T3 is not really used in this country.

 

Yeah, I think I wrote my first programs in

 

CD,
Though my experience in very removed here, I would also reitreate what 2kturkey pointed out, overhead. Frame and block headers do tend to eat some bandwidth, but I am sorry that I can't say how much. Consideration needs to be given to that layer of protocol.
Good luck.