Basic question about frame relay and ATM

[wim_depauw]

Hi,

I'm studying for my CCNP and I got a basic question on frame relay and ATM .

What is the exact difference between both protocols ? In the bcran study guide they say that a lot of times you have a frame relay switch and that afterwards the packet is ATM switched .How do you do this ?

thx

wim

[pkhatri]

Wim,

One of the fundamental differences between frame relay and ATM is that FR switches variable-sized frames whereas ATM switches fixed-size cells.

You will find that a lot of providers offering FR services have ATM switching hardware in the core i.e the customer facing interface may be FR but the trunk links are ATM. Therefore, while the customer gets what appears to be a FR service, the data is actually carried (i,e switched) as ATM cells within the provider's core.

HTH,

Paresh.