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ATM vs IP

Can any of you who work for VZ tell me if there are ATM switches in the core network?

Many data networking textbooks seem to diss ATM (asynchronous transport mode), mainly because it's not a creation of the IETF (internet engineering task force) and is only used deep within the public telephone network core.

From my reading of what ATM is and what it was intended to do, it should've gotten more "air play", but seems to be overtaken by IP-based networks.

Any thoughts?

Comments

JoeSmith

ATM and IP work on seperate layers...

jumpin68ny

ATM is transport. IP traffic can traverse an ATM network. They are two very different things.coo

To compare, ATM is transport like Ethernet. IP runs over ATM or Ethernet.

mcaranci

What you say is only partially true, for ATM AAL5 (ATM Adaptation Layer 5) was designed by the internet community specifically for variable bit rate (VBR) handling data.

However, there is also AAL1 for constant bit rate (CBR) signals, e.g., voice or real-time video, and not bursty data.

So while ATM can carry data, it need not.

And while data can travel over an ATM network, it need not.

My understanding was that ATM is both a transport protocol, as well as a network protocol in its own right.

lasagna

The key here really is that the "Internet" as we know is an IP-based protocol network. Regardless of the underlying transport, at the end of the day the end-to-end communication is over IP. So while ATM has the ability to do some pretty interesting things, particularly in the voice and video world (particularly because of the small cell size), it's actually not the greatest thing when it comes to large size packet protocols like IP.

A more interesting discussion might be around MPLS and the use of traffic prioritization and multiple VRF's for delivering multiple network services to a home market.

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