What is the difference between STM & ATM multiplexers?

Answer 1

Hi lekh raj b

You may have your terms mixed up. STM is the synchronous transmission module for SDH (synchronous digital hierarchy). SDH is a generic layer 1 protocol similar to the north american SONET. SDH is an advance on time division multiplexing (interleaving 64k channels) - the STM frames are T1 or higher multiplexes. STM-1 is a standard speed of 155Mb/s.

On the other hand ATM is asynchronous transfer (transport) mode - a layer 2 datalink protocol for WANs. Telcos use ATM to multiplex ADSL channels into (typically) DS-3 hand-offs to internet providers, but ATM isn't primarily a multiplexing protocol.


Hope this helps!
The Chicken