Foundry Extends Server Load-Balancing Reach

Foundry Networks next week will give e-commerce customers more options for server load-balancing, as the company updates its switch software to match competitors' capabilities.

Foundry's Internet IronWare 6.0 distributes Web-based requests among servers in different locations, a capability that competitors such as Cisco and Alteon WebSystems have had for some time.

The new version also maintains persistent sessions, ensuring that all packets for a particular session go to the same server. The software can determine which packets belong to the session based on cookies, much like a capability Alteon announced in November (NW, Nov. 15, 1999, p.14). It can also use the Secure Sockets Layer session ID to identify packets.

Intira Corp. is looking at global server load balancing to distribute loads among data centers in St. Louis, New York and Pleasanton, California, says Dan Rabb, lead network engineer at the company. Intira manages IT and network infrastructure for clients conducting e-business.

Distributing servers among different locations can cut down on response times, as users can access the site closest to them. Rabb says Intira is interested in technology that ensures servers are available, keeps response time low, and helps the company meet its service-level agreements.

Although other vendors provide for global server load balancing, Foundry does it slightly differently, says Chandra Kopparapu, product marketing manager at Foundry. Others take over the features of the Domain Name System server, but Foundry's software works with an existing DNS server, he says.

Also, when Foundry's product decides which site to route requests to, it takes into account how much of a load each site already has. If a site is already receiving a lot of requests, the software will choose a different site.

In addition, Kopparapu says the software measures the health of different sites, tracking how quickly packets travel between the sites and users access the data. This way, future packets are routed to the site with the fastest response time.

"The health-checking just sold it for us," says Curtis Hays, principal network architect at Infospinner, which develops application server products. The company wanted to be able to see which applications were up and running from the viewpoint of the network gear.

Version 6.0 also uses cookies -- that is, bits of data that identify users -- to determine to which server to send requests. A server can tell Foundry switches that cookies of a certain type should be directed to it. Each packet from the same user in the same session can be directed to the same server. If the user is ordering multiple items from the Web site, such persistence is necessary to make sure the server manages the transaction from start to finish.

Version 6.0 is shipping now as a free upgrade to Foundry's ServerIronXL and BigServerIron switches.

Foundry: http://www.foundrynet.com

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