NERD ON THE STREET

Tibco and Cisco Systems have formally submitted their reliable IP multicast specification to the Internet Engineering Task Force (IETF). Dubbed the PGM Reliable Transport Protocol, it was developed by Cisco and Tibco to ease network management tasks for applications such as desktop conferencing, software distribution, stock quotes and real-time news distribution and messaging. While Globalcast Communications announced its support for the proposed industry standard, other companies such as Intel and Microsoft are reviewing it. For financial markets, IP multicasting helps decrease network traffic. When 100 users require a data item, like a currency quote, it must be transmitted to each user in turn as a separate message. That's 100 messages every time the currency quote changes. With multicasting, the server sends just a single message for each quote update and the network does the traffic replication instead of the server hardware. However, multicasting is inherently unreliable--there is no acknowledgement that a data item that has been transmitted has been received by all that require it. To add reliability to IP multicast requires additional protocols such as PGM. Tibco's vice president for TIB products Mark Bowles says he expects the IETF to take 1½ to two years to complete the standards process. In the meantime, Tibco will be offering an evaluation version of PGM while Cisco will eventually offer PGM as part of its IOS operating system for its networking hardware.