Switching to the fast lane
- By Cheryl Gerber
- Jun 27, 1999
Because of their speed and simplicity, network switches are replacing hubs and routers as the dominant form of internetworking in local-area networks today.
Federal agencies are making the leap away from hubs and routers to take advantage of new capabilities offered in the latest generation of network switches. In particular, products able to take on routing functions as well as switching are gaining popularity.
In addition, switch vendors are introducing World Wide Web interfaces into their products to make them easier to manage and policy-based networking capabilities to add intelligence and business prioritization to network switching.
But most important for many users, switches also can offer more bandwidth, said Tim Hale, senior product marketing manager at 3Com Corp., Marlboro, Mass. "Each port on a switch is a dedicated
10 or 100 [megabits/sec] Ethernet connection. That's a lot of bandwidth. With hubs and routers, users don't have a dedicated connection."
Time for a Switch
Charles Rutstein, an analyst at Forrester Research Inc., Cambridge, Mass., noted that most users today are installing Ethernet switches in their LANs, which scale up from 10 megabits/sec to 100 megabits/sec. Coinciding with this trend has been a rise in the installation of switch routers, which take on some of the functionality performed by traditional routers, Rutstein said.
"The deployment of switch routers has been robust both to re-architect and to replace aging routers," Rutstein said.
Switches operate on Layer Two of the Open Systems Interconnection stack, an international standard that defines networking protocols in seven layers. Layer Two is the data link, which transmits from node to node. Routers operate on Layer Three, the network link that routes data to different networks.
Hybrid routing switches combine the speed and simplicity of the Layer Two switch with the intelligence of the Layer Three router by operating on both layers. "Routers have protocol intelligence, which enables them to handle multiple protocols," Rutstein said. "But switches are simpler. They don't care about protocols, so they are able to transfer packets at wire speed."
The Naval Postgraduate School, Monterey, Calif., made use of routing switches when it began to upgrade its internal network architecture last year. The school hired Monterey-based integrator International Automation Associates to design and install an intranet based on an Ethernet LAN and an Asynchronous Transfer Mode wide-area network. IAA installed 3Com's CoreBuilder 3500 routing switches between the Ethernet and ATM networks.
Doug Picard, president of IAA, explained that routing switch technology is embedded in application-specific integrated circuit hardware rather than in software, which makes the switch more efficient. Traditionally, routing technology has resided in software while switching has been performed within the hardware.
According to Picard, routing switches provide speed and simplicity that are not available through traditional networking architectures. "It's incredibly fast and simpler than a router," he said. "It's all done in silicon - in hardware - so you don't have to run it in the operating system, requiring a CPU to process frames."
The Naval Postgraduate School's network spans 4,500 nodes, many of which are used by students enrolled in a master's degree program that requires extensive research, said Tom Halwachs, chief information officer at the school. Halwachs needed a three-tiered ATM backbone to support the high-bandwidth and multimedia demands of his users.
Halwachs said the 100 megabits/sec circuits enable his staff to conduct online meetings using audio and video. "We use the desktop as a telephone and for video. It saves shoe leather running back and forth from the boss' office."
Halwachs is evaluating the possibility of layering the telephone system on top of the ATM WAN.
The Naval Postgraduate School uses 3Com's ATM switch, the CoreBuilder 7000, as a core network backbone switch, 3Com's Hale said.
The school also uses 70 SuperStack II 3300 switches, 3Com's 10/100 Ethernet switches.
As federal users have begun to utilize routing switches when redesigning their networks, they also are taking advantage of the new Web interfaces that have been incorporated into these products. "Virtually all of the switches and routers [being shipped] either have or will have Web interfaces for management," Rutstein said. "It's a least common denominator way to talk to any internetworking device instead of requiring specific software for each device."
The Department of Veterans Affairs in Baltimore uses Cisco Systems Inc.'s Web-based solution, the Cisco Visual Switch Manager (CVSM), to manage its midtier Cisco 2900 switches.
The VA's Maryland health care organization uses a broad array of Cisco switches for its LAN and WAN. "Cisco really offers an end-to-end solution that can fit 90 percent of the users out there," said Marcelo Silva, network manager for the Information Resource Management Service at the VA's Maryland organization.
Silva said previous Cisco software did not allow him to change the design on the network easily. But CVSM - which provides a browser interface and statistical information on switches, routers and access servers - solved these problems, he said.
"We can do inventory to see if PCs or a device has been moved," Silva said. "We have a central point of access to information."
Silva said he likes the breadth of Cisco switch offerings and is pleased with their maintenance and configuration performance. But he was not entirely happy with the software until Cisco released its CiscoWorks 2000 network management solution.
CiscoWorks 2000 gives users the ability to monitor switches on their networks using the Simple Network Management Protocol, the standard method of managing devices over any network that can speak Transmission Control Protocol/
Internet Protocol, the protocol on which the Internet is based.
Silva added that he also would like to see Cisco offer "more Web-based solutions instead of proprietary software for the lower- and higher-end switches."
Bob Deutsch, federal systems engineering director at Cisco's Herndon, Va., office, said Cisco is moving from proprietary to Web-based management to cover its whole family of switches.
"Web-based solutions solve a significant problem," Deutsch said. "Platform independence [provides] a huge payback, not just to our customers but also to us. We've had three to four different hardware platforms with different operating systems to support."
Other federal users echoed Silva's view that Cisco hardware performs more to their satisfaction than the company's software does.
"Cisco hardware is further along than its software," said Roy Greene, a network manager at the State Department's Bureau of Diplomatic Security. "Cisco management tools don't always match what the switch is capable of."
Greene agreed that CiscoWorks 2000 is an improvement over earlier versions of CiscoWorks. "There are more functions, and it's easier to use," he said. "They put more work into this."
Know Your Priorities
The ability to set quality-of-service parameters is one of the newest enhancements in today's switches. Once industry established the standard for prioritizing Ethernet traffic, all of the major switch vendors began to support policy networking, which is a way to reserve bandwidth for types of network traffic that are predesignated as most important to the user.
Forrester's Rutstein said he views policy-based networking as an attempt to align business and technology. "Most switches simply forward packets as quickly as they can without regard to what's in them," he said. "The advent of policy networking and quality of service introduces intelligence so [the network] can make decisions about which packets are more important than others."
When the Army's Redstone Arsenal in Huntsville, Ala., wanted to upgrade from a 10 megabits/sec Ethernet LAN to one running at 100 megabits/sec, it chose Foundry Networks Inc.'s FastIron switches with IronView network management software. Foundry Networks' solution will give users the ability to prioritize network traffic to ensure that bandwidth is available for critical applications.
"[The Army's] Pentium workstations had 100 [megabits/sec] network interface cards. So to take advantage of that, we upgraded switches," said Doug Glanden, project leader at Nichols Colsa Computer Information Management, a Huntsville-based joint venture working on the arsenal's network.
Foundry Networks' hardware and software proved reliable, and the company's support was above average, Glanden said.
Bobby Johnson, president of Foundry Networks in Sunnyvale, Calif., said his company's graphical user interface enables users to view one or more systems, drilling all the way down to the port level on an individual switch. He said users can use the GUI to change port speed and set quality-of-service parameters.
3Com's Hale said all 3Com products support policy networking. Cisco's Deutsch said his company will release CiscoAssure, its switch policy management solution, within the next six months.
However, as networks grow more complicated and switches take on more router functions, it becomes more difficult for users to identify which switches to use in various circumstances.
"As Cisco's product line grows broader, there are more niche solutions that can be achieved, and it can be hard to differentiate between them," the VA's Silva said. "But Cisco has offered seminars to help us."
Despite the growing complexity of switches, the increased selection and functionality serves users well. Rutstein said users historically have upgraded switches every 18 months to two years. But today, he said, users can install a switch that should serve them for five years without an upgrade. "We're coming to the end of the rapid upgrade cycle," he said.
-- Gerber is a free-lance writer based in Kingston, N.Y.
AT A GLANCE
* Status: Agencies are rapidly replacing hubs and routers in their local-area networks with switches. These users are taking advantage of new switches that incorporate router functionality, include World Wide Web interfaces for switch management and enable users to reserve bandwidth for high-priority traffic.
* Issues: Vendors are just beginning to introduce these innovations into their switches, and in some cases software functionality has not kept pace with hardware innovations. In addition, users are finding themselves faced with a confusing array of options for switching solutions.
* Outlook: Bright. Vendors continue to increase the functionality of their switches, and users have been encouraged by advances in the areas of switch management and policy-based networking. Users can look forward to switches that can serve them for up to five years without an upgrade.