bandwidth

[pccthailand]

Hi all,

I have WAN link BW 64Kbps, this rate is transmit 64Kbps and recieve 64Kbps (total 128Kbps) or transmit + recieve is 64 Kbps

Thanks

[pkhatri]

Hi,

A bandwidth of 64kbps means that the link can receive at 64kbps and transmit at 64kbps. This must NOT be construed to mean that the link is a 128kbps. You should consider the link to provide 64kbps of full-duplex throughput.

Hope that helps - pls rate the post if it does.

Regards,

Paresh

[arvenugopal]

Paresh,

This means you have a full duplex connection for a given link, the total Bw will be 64Kbps not 128, also the signalling needs to taken care. it will be slightly less then 64K

[pkhatri]

Yes.

Not sure why you think signaling is of any importance as far as the raw throughout of a link is concerned. The effective throughput of a link at a given layer (layer 2 or 3) will, of course, depend on things such as signaling.

Paresh.

[pccthailand]

Hi

I think if we have LAN 100Mbps then full-duplex will give u total bw is 200Mbps. if my WAN connection BW is 64Kbps and full-duplex , the totally BW is 128 Kbps same LAN ?

thanks

[pkhatri]

Hi again,

That is marketing-speak, where they will market routers/switches as twice their actual bandwidth e.g. vendors will market routers that forward 10Gbps full-duplex as 20-Gbps routers.

However, that is not really important. You can say that you get 200Mbps with a fast-ethernet link provided you indicate that you are adding up receive and transmit bandwidth. In the same way, you can use this to describe a full-duplex 64kbps link as one that gives you a total of 128kbps bandwidth if you consider the receive/transmit directions separately. However, if you are gonna describe a link as suc, you have to explicitly state how you arrive at the figure. What I mean is: if you say a link is 128kbps, then that generally means that you are getting 128kbps in the receive direction and 128kbps in the transmit direction and not 64Kbps of transmit + 64kbps of receive.

So my recommendation is to use the full-duplex bandwidth to describe links, not the summation of the individual directions.

Paresh.

[Richard Burts]

I think that Paresh makes a good point. We need to be careful about how we use terminology, and especially terminology where vendor marketing departments will sometimes re-interpret the meaning of terms. Usually we speak of bandwidth as describing the amount of data that can be transmitted. You can certainly say that your WAN link has a capacity of 128k since it can do 64k in both directions. But I believe that most of us understand bandwidth in a technical sense to describe the one-way capacity of the link.

For terms like bandwidth that are subject to different interpretations it is important to be clear about what we mean and to be consistent in how we use the terminology.

HTH

Rick

[pccthailand]

Hi

" WAN is share medium bandwidth " this words is truth?

Thanks