News Release

Cisco Systems Offers First Commercially Available Implementation of AIW Version Two Standard for Data Link Switching

New Features in Cisco's Data Link Switching Plus Offering Increases Network Performance
May 09, 1997

Research Triangle Park, NC, - May 9, 1997 - Cisco Systems, Inc. is the firstvendor to announce the availability of Data Link Switching that complies with theAPPN Implementor's Workshop (AIW) Data Link Switching (DLSw) Version 2 (V2)standard. Cisco is also introducing two new enhancements to its Data LinkSwitching Plus (DLSw+) offering. These enhancements extend beyond the AIWstandard by increasing network performance and scalability while decreasingnetwork response time.

The AIW V2 DLSw standard was designed to address the scalability limitations ofenterprise networks handling Systems Network Architecture (SNA) and NetBIOStraffic between branch offices. The new standard employs an Internet protocol(IP) multicast technique to forward broadcast traffic, which can greatly reducewide area network (WAN) traffic in networks that require branch to branchcommunication.

In addition, the new standard allows DLSw routers to communicate withoutspecifically being configured to each other, greatly simplifying the network. This feature, called peer-on-demand, was implemented in 1995 in Cisco's DLSw+,the successor to Cisco's original DLSw solution, and is now part of the AIW V2standard.

The AIW V2 DLSw standard focuses primarily on fully meshed networks on thescalability issues. By contrast, in hierarchical networks, Cisco's DLSw+, hasproven scalability in several production networks with over 1,000 branch sites.Cisco's DLSw+ has been widely deployed in over 100,000 routers worldwide.

New Data Link Switching Plus Features

Cisco is also announcing two new DLSw+ features, border peer caching and SNA typeof service (TOS). Cisco's border peer caching feature extends beyond the AIW V2standard by further reducing broadcast traffic. This feature automaticallybuilds and maintains a distributed directory of SNA and NetBIOS resources so thatbroadcasting only occurs the first time any branch router needs to find a networkresource. With the distributed directory, requests from other branch routers areforwarded directly to the correct site. By eliminating subsequent broadcasttraffic, Cisco's implementation greatly enhances network performance and extendsscalability. By comparison, AIW V2 DLSw standard requires each branch router tomulticast an explorer at least once. This additional broadcast traffic canpotentially impact network performance.

Another new DLSw+ feature is SNA type of service (TOS). Cisco's SNA TOSpreserves SNA traffic prioritization across an IP backbone, minimizing responsetime for mission critical traffic. SNA TOS dynamically maps SNA Class ofService to TCP/IP TOS. This feature prioritizes mission critical SNAtransactions ahead of SNA batch or File Transfer Protocol (FTP).

"Again, Cisco proves that it will lead the pack with Data Link Switching Plus,"said Anura Guruge, an independent consultant for SNA environments. "While theAIW standard ensures interoperability, the enhanced features of Cisco's Data LinkSwitching Plus are essential in any network with mission-critical SNA traffic."

Cisco Systems

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