MENLO PARK, Calif., April 27, 1992 -- A flow-control capability that addresses traffic congestion problems in larger source-route bridged token ring internetworks has been added to the Cisco Systems family of router/bridges.
Cisco is the first router vendor to offer Data Link Control (DLC) layer flow control. Incorporated into Cisco's LLC2 local termination software, this feature enables the router to throttle end stations in source-route bridged token ring networks when buffer utilization in the router reaches a threshold; at this point the router quiets the end station until the congestion clears.
Michael Zadikian, Cisco's SNA product manager, said, "Flow control will be of critical importance in internetworks characterized by a large number of token rings with high utilization rates. Without this capability, congestion caused by network delays and exceptions can result in lost sessions and even network gridlocks due to buffer depletion. Now the router can, in effect, gracefully prevent new packets from entering until buffers are replenished, which improves network availability and reliability."
The enabling technology for flow control -- local session termination -- was announced in January as part of Cisco's Phase III plan to support internetworking in IBM environments. Designed to prevent session loss during delays between widely-separated LANs, it improves network availability and reliability. When data are sent between two hosts separated by a WAN, for example, the DLC session initiated by Host A, rather than spanning the backbone, terminates at the local router, which locally acknow- ledges frames received from Host A. The router then sends the data on to Host B, guaranteeing reliable transport and delivery.
Flow control is available as part of the bridging software option for Cisco routers, which includes a wide array of other IBM internetworking features. The bridging software is priced at $450 to$1,800 depending on router chassis size.
Cisco Systems, Inc., is the leading global supplier of high- performance, multimedia and multiprotocol internetworking products, including routers, bridges, terminal servers and network management software. Cisco technology can be used to build enterprise-wide networks linking an unlimited number of geographically dispersed LANs. Cisco is publicly traded over-the- counter under the NASDAQ symbol CSCO.
Posted: Dec 15 13:33:12 1992
