The evolving switch

When the Alberta Auditor General’s office installed new network switches last spring, security concerns and its existing relationship with Juniper Networks, Inc., were key decision factors. Shawn Dineen, infrastructure services team leader, says the Juniper switches integrated well with other Juniper hardware already in place, and their network authentication capabilities addressed security concerns that come with handling sensitive government data.

For Winnipeg-based customs broker GHY International, future plans for voice over Internet Protocol meant quality of service provisions and Power Over Ethernet capability were concerns. Nigel Fortlage, GHY’s vice-president of information technology, wanted one way to manage the whole network, so standardized on Cisco Systems Inc.

And for Rusty Fraser, director of IT at Signature Vacations in Mississauga, Ont., reliability is vital but cost ultimately led the long-time Cisco shop to Juniper switches, saving about $40,000, Fraser says.

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Many things affect the choice of network switches.

Most people think first of speed. Today, says Mark Tauschek, senior research analyst at Info-Tech Research Group in London, Ont., the norm is gigabit per second in the network core and 100 megabits to the desktop, but increasingly, new installations supply one gigabit to the edge and 10 gigabit at the core.

Not everyone needs that, Tauschek says. and 10/100-megabit switches are still cheaper than gigabit, so Tauschek’s advice is “if you don’t need that bandwidth, then there’s really no need to spend the money on it.”

Yet lower costs lead more buyers to choose the extra speed. Dineen, for instance, says there wasn’t a pressing need for more bandwidth when he bought new switches last spring, but “the cost of gigabit switching now is so good” that his network is now all gigabit. So is Signature Vacations’ network. GHY currently uses 10/100 equipment, but Fortlage plans to move to gigabit in the core.

Layer 3 switching is also spreading from core to edge.

Switches always handle layer 2 of the OSI network model, the data link layer. But there are also multilayer switches, most commonly operating also at layer 3, the network layer.

Layer 3 capability has been most common in the core of the network, but extending it to the edge improves manageability, says Ahmed Abdelhalim product marketing manager for Ethernet switching products at Brocade Communications Systems Inc., and operating costs fall because consistency from edge to core simplifies training.

Layer 3 obviates the need to use the slower Spanning Tree Protocol to route traffic, which improves performance. “Spanning tree is probably the number one cause of headaches,” says Bobby Guhasarkar, senior manager of product marketing for Juniper Networks Inc.’s Ethernet platform business group.

William Choe, director of product management for Cisco’s Ethernet switching and technology group, says 25 to 30 per cent of today’s network deployments provide layer 3 capability to the edge.

Dineen implemented multi-layer switching throughout his network for compatibility with Juniper’s Unified Access Control and the 802.1x network access control standard.

Growing use of voice and video have increased the demands on networks in general and on switches in particular. “If you go back 10 years to when the quality of service discussion started,” says Trent Waterhouse, vice-president of marketing at Enterasys Networks, Inc., “voice and video were kind of a future thing. Now it’s an everyday thing.” So switches must prioritize network traffic.

Multilayer switches can prioritize at layer 3, says Tauschek, but layer 2 switches can also do it provided they support the 802.1p protocol.

Along with the ability to prioritize, Waterhouse says, should go the ability to restrict bandwidth allocated to certain types of traffic. Without that, he argues, traffic with the highest priority could crowd out all other traffic.

And Guhasarkar says the number of hardware queues per port determines how many categories a switch can sort traffic into.

Though GHY is not running voice over IP today, Fortlage expects to do so within three years, so quality of service is important and so is support for Power Over Ethernet, which allows network devices like IP phones to draw their current directly from the network.

This has benefits besides not having to plug in IP phones, Choe notes. “You can back up the power at the wiring closet,” he notes – more practical than attaching an uninterruptible power supply to each device.

Guhasarkar says total cost of ownership, always important, is even more so today. It’s affected by many factors, like management and support costs and energy efficiency.

Hewlett-Packard Co. recently launched new data-centre switches, the ProCurve 6600 series, designed for energy efficiency. And Cisco unveiled an energy management initiative allowing its switches to measure and regulate the power consumption of other devices.

Energy matters most in data centre switches. “You can only provide so much power in each rack,” says Erik Pounds, Brocade’s product marketing manager for Fiber Channel switching products, who says he has seen racks partly empty because power wasn’t available to support all the switches they could hold.

Edge switches are hardly power hogs to begin with, Tauschek notes, and choosing an edge switch for its energy efficiency won’t make a large difference to cost of ownership over the life of the equipment.

While other factors such as layer 3 support also affect manageability, Tauschek suggests looking closely at management software supplied with switches.

Dineen likes Juniper’s Virtual Chassis technology, which allows the Alberta Auditor General’s office to manage multiple devices as if they were one machine. Management takes much less time than with previous gear, he says, and it’s also easier to add new switches.

Finally, Tauschek says, consider reliability. He questions vendor claims – can a vendor really know a newly introduced switch design has a mean time between failures of eight years, he wonders – but suggests looking at warranties and support charges. He praises Hewlett-Packard Co. for the comprehensive warranties on its ProCurve network gear, for instance. “These guys are backing up their products.”

Fraser says he examined vendors’ reputations, sought advice from Signature’s reseller and spoke to customer references before buying. Homework is required – there’s more to buying switches than you might think.

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