Fundamental problems in interoperability and IP standards still need to be addressed for the convergence of voice and data networks to be viable in corporate environments, delegates at last week's Gigaworld conference in Barcelona were told.
"IP as an underlying transport protocol will have problems because IP is not predictable," said Kiran Narsu, research leader of Giga Information Group.
Narsu said that while vendors strive to incorporate Quality of Service (QoS) capabilities, the problems of integration, scalability and interoperability have yet to be addressed.
For example, 3Com, Nortel and Cisco hardware devices have different mechanisms for assigning Type of Service (ToS) within the three byte flag designated for this purpose in IPv4. Until such fundamental problems are resolved, interoperability - so vital for the delivery of convergence in mixed shops - will not be possible.
"Convergence will not be a reality for three years," said Narsu.
Kurt Bertone, Nortel's VP of networks and architecture Emea, admitted that vendors were guilty of hype. He speculated that the last circuit switch might in fact stay in operation until 2162.
"If you take away the hype the direction is still there," said Bertone. "It won't happen overnight, but convergence is the way the world is going because next generation networks based on pure IP can be built quicker and at lower cost."
Bertone admitted that vendors needed to address interoperability issues and develop standards. Those of particular concern were: assigning priority to different services, enabling policy engines to talk to each other and incorporating signaling support.
For its part Nortel is carrying out widescale interoperability testing and incorporating QoS capability on its infrastructure products. It is also developing its management platform Optivity, so that it can manage high end switches, such as the Passport range, and PBXs as well as addressing convergence at the application level.
There are currently unresolved issues in the path to directory enabled, policy based QoS. There is no standards based mechanism to properly map ToS bits used in DiffServ onto the 802.1p prioritisation bits in an Ethernet frame. Giga expects that this will not show up in products until early 2001.
MPLS (Multi Protocol Label Switching) specifications are largely complete, but the signaling mechanisms are not. Carriers are not expected to offer these MPLS services before 2000.
Directory synchronisation is possible, but it adds considerable overhead to an enterprise network - especially where multiple remote sites are involved.
In order to support QoS in the enterprise, massive hardware and firmware upgrades need to be coordinated for all interdependent products, for example, network aware switches, core and edge routers. Multivendor interoperability in campus network products is not expected before 2000.
For more stories see this week's issue of Network News UK
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