title: My last ATM column?

By: Scott Bradner

Last night a bunch of us were sitting in a quite nice restaurant near Napa California drinking some quite nice wine. The group consisted of me, some venture capitalists (VCs) and our SOs. At one point in the evening the talk naturally turned to ATM. One of the VCs said that as far as he was concerned ATM's role was only as the access technology for the last 100 feet. That seemed reasonable but I got to thinking and I'm not sure he was quite right. (At this point I expect my editor will want to expand the ATM acronym to "Asynchronous Transfer Mode," but I think that is more than a bit silly. It would be one thing if the expansion produced something that made any sense but quite another when it produces something that sounds like the name of a bad punk rock band.)

To some people ATM is closer to a religion than a technology. You can tell most of the true believers by the slight Bell shape to their heads but a few have been under cover -- able to masquerade as normal Internet geeks. Talking about the future of ATM with true believers, or with the knee-jerk ATM abolitionists, is a pointless waste of time. Luckily the real world shows up every now and then and renders many absolutist positions irrelevant. After a while it became clear to even the most ardent ATM fan that 155 Mbps ATM to the desktop at the same or higher price as gigabit Ethernet was not a good strategic plan.

The VC might be correct in thinking that a good place for ATM is in access link multiplexing but he was ignoring the presence of many ATM true believers in the traditional telephone world. Since they cannot conceive of a datagram network that could provide the quality of service (QoS) service level agreements (SLAs) that they think they need they will continue to use ATM in their networks. People from the datagram world who know that the right architecture in a datagram network will do just as well might have a competitive advantage but the phone folk have the money these days.

The other place I think the VC might be wrong is that the stuff that looks like ATM in the access networks, ADSL being an example, is not "real" ATM - its just ATM cells - there are none of the ATM QoS features that defined ATM for most people.

This may be my last column about ATM, it's hard to get too worked up about a technology whose relevance to real world data networking is as tenuous as ATM's is. (Sort of like the relevance of Thunderbird to the wine we had last night.) But then again, some of the ATM folk are now disguised as MPLS proponents, there may be reason to bring ATM up again.

disclaimer: Harvard banned wine (good or bad) from the dorms a few years ago and has not expressed an opinion of wine quality or ATM since.