Late last summer, executives at several OEM and component companies warned their technical staffs that membership in the Digital Subscriber Line Forum, Frame Relay Forum, Asynchronous Transfer Mode Forum, Metro Ethernet Forum, Multi-Protocol Label Switching Forum and Resilient Packet Ring Alliance was more than tight budgets could bear. Since most forum activity was geared to Layer 2 data-link unification, the managers argued, why not lump everything under a "Layer 2 Forum" banner?
Toward the end of the year, a pact between the Metro Ethernet Forum (MEF) and the MPLS Forum on implementation agreements showed that collaborative work might be expanding. But a shotgun wedding among all the Layer 2 organizations has yet to take place.
That should surprise no one. Groups like MEF and the DSL Forum, as well as other coalitions such as the Optical Internetworking Forum, spend at least as much time on physical-layer interface standards as on higher-layer interworking. Is there really a common problem set facing packet transport over diverse media that would justify common bonds?
Yes, with caveats. Where commonality can be discerned, there's a little latent irony dwelling in the supercoalition idea. The joint implementation agreements being developed by MEF and the MPLS Forum reside in common service offerings, such as virtual-private-LAN services; in methods to achieve committed information-rate packet transport; in fast-reroute concepts that would give packet transport a Sonet-like sub-50-millisecond recovery; and in guaranteed-bandwidth concepts that could make packet flows appear to be a virtual-circuit service.
If you're feeling deja vu, it's because this wish list resembles the list compiled by the ATM Forum in the mid-1990s. ATM as the Grand Unifier crashed and burned as it got closer to the desktop, because the acceptance of universal 53-byte cells entailed too high a cost for too much of the installed PC base. LAN emulation on a PC network interface card was far more expensive than retaining the familiar Ethernet cards and leveraging much of the old infrastructure to bridge networks from desktops to global grids.
Proponents of a common Layer 2 fabric are really talking about three distinct standards dwelling between physical and transport layers. Ethernet is the default framing structure at Layer 2, MPLS is being accepted as the best packet flow-assignment tagging method at Layer 2.5 and Internet Protocol is virtually the only game in town at Layer 3. Paste them together with virtual-circuit and quality-of-service schemes, and the whole enchilada resembles ATM, even if this enchilada was assembled from leftovers instead of fine carne asada.
The coalitions mentioned above face enough common problems to warrant joint meetings and implementation agreements. But budget-conscious corporate management should realize that a total merger of networking coalitions is about as likely as a full merger of the IEEE and Internet Engineering Task Force.
Loring Wirbel is editorial director of Communication Systems Design and the editorial director for CMP Media's Communications Initiative. He can be reached at lwirbel@cmp.com.
