ATM Versus Frame Relay

Due to the cell based nature of ATM (really could be called Cell Relay), it is better suited to voice than Frame Relay.

ATM, in fact was specifically designed to support voice data and video over a single media. The 53 byte cell is a compromize between the ideal transmission unit sizes for each type of transfer. Data would like to have a large size for overhead efficiency, while voice and video work best with tiny packet size for minimal latency.

Since ATM uses smaller packets (53 byte cells) than Frame Relay (large frames), it is by design better for voice.

Additionally, ATM is designed to carry voice directly (that is why EVERY major long distance and most local telephony providers use ATM for their voice networks). I do not know of any way to do this with Frame Relay. You would have to use Voice-Over-IP or some other workaround to do voice on Frame Relay.

In addition to the above answer, be aware that sending IP traffic over ATM generally cuts your transmission rates to around 80% of what you think your link should bear due to padding in the cell sizes. There are specific packets (ACK and a few others) that do not play well in the 53 byte packet size. This will lower your data rates. Other than that ATM is ok for voice and video, but straight data suffers. A comprimize was probably not the best idea.

You can have your cake and eat it too. Today Frame and ATM are not really competing technologies. ATM Internetworking allows you to use both technologies and implement each one where it makes the best sense from a cost and requirements perspective. Quite often carriers will offer attractive deals because this is not a tarrifed offering.

Frame Relay Network does not use error correction logic, and It QOS is limted. Where as ATM is 53 cell relay technology, with Better QOS, It is advisable.
Vinayak

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