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How do I compute the amount of data that a FR T-1 can transfer in 1 hour?

I know a Frame-relay circuit provisioned with a CIR of T-1 is 192KBps (1.5Mbps/8bits). In one hour, 694800 KB (679MB) can be transferred. However, how much of this 679MB is used by SMB, UDP, IP, and Frame-relay? I need to know the net amount of data (documents, spreadsheets, email, etc.) that would be transferred from a file server hard drive on one side to a file server on the other end of the Frame-relay circuit.

How does this value change when the packet size is changed?

What about the overhead of the SMB or TCP acks?


Re: How do I compute the amount of data that a FR T-1 can transf

It would be fairly impossible to come up with an absolute number; the best you could do is a "Best Case" and "Worse Case" that figures in the absolute maximum and minimum amount of overhead (frame & packet size, maintenance protocols, routing protocols, etc).

The good news is that you only have to calulate it for one direction: T1 is full duplex, so response traffic would not have any bandwidth-related impact on the traffic (the response would be going the other way on the other pair).

The biggest variable is the application traffic. There is no specific size; just a minimum and maximum packet & frame.

If you know specifically what the primary / predominant traffic will be (Email, DB updates, etc) then post 'em. Perhaps others with similar traffic flows can provide some insight.

Good Luck



Re: How do I compute the amount of data that a FR T-1 can transf

Your making a big assumption that you can get full t1 throughput. The biggest factors affecting performance are distance and protocol. Handshake intensive protocols will loose a lot of throughput waiting for acks. Protocols using large sliding windows will get closer to the circuit speed but never quite get there. I have several frame t1s. Ping throughput tests get around 480kbps on one that is 30 miles away and 240kbps for one that is 1300 miles away. That is handshake intensive even though its not connection oriented because each ping has to get an anser or time out before the next one is sent. However FTPs get around 1.1 mbps thoughput to the far site. They use a sliding window but they still fill it up and have to wait for acks sometimes.

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