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Switching Switches

As networks grow and become more complex, managed network switches may be worth the extra cost and time it takes to put them through their paces.

Unmanaged or managed switches? That is the question. Whether ’tis nobler to suffer the slings and arrows of unmanaged network traffic or to take up the extra cost and complexity of intelligent switches. Had Shakespeare been an IT manager, Hamlet’s famous soliloquy might have reflected the dilemma faced by many network administrators today.

As fast-growing small businesses add devices, users and segments to their networks, complexity grows and performance can suffer. Building a network infrastructure using simple, low-cost Ethernet switches works fine for small networks that don’t have demanding performance requirements. But today’s small business networks are increasingly complex and vital to the operation of the business, which is why many are turning to the performance and management control offered by managed network switches.

Accelerating the move toward managed switches is the parallel shift toward higher-speed Gigabit Ethernet, also known as Gig-E or 1000BaseT. Increasingly popular for backbone networks that interconnect servers, steadily declining prices are making Gig-E evermore affordable for connecting desktops and other devices on local area networks. And as businesses look to upgrade network switches to the new high-speed technology, they are faced with a choice between inexpensive unmanaged switches and intelligent devices that offer more control and management features.

Managed switches may be the best choice — whether a business is looking to improve network management or upgrade performance, since they can regulate and route traffic and provide the kind of control that can make an administrator’s life easier in the long run. Managed switches come in two types: Layer 2 and Layer 3, which refer to the levels of the network protocol stack (delineated since the 1980s by the International Standards Organization’s well-known seven-layer model) that they control.

Layer 2 managed switches can enable and disable individual ports, apply rules to the packet routing including simple prioritization and segment groups of physical ports into virtual LANs (VLANs) for security or traffic management. They operate at the packet level and act only on network node addresses — they pay no attention to the contents of the packet.

Layer 3 managed switches do all that Layer 2 switches can do but they also understand the protocols used to route packets across the network as well as the end-node address data. This allows Layer 3 managed switches to provide finer control of traffic based on both protocols.

Pricey Sophistication

Naturally, that sophistication comes at a price. A 16-port unmanaged Gigabit Ethernet switch cost Carl Oppedahl, a patent and trademark lawyer and partner at Oppedahl & Olson LLP in Dillon, Colo., about $180, or slightly more than $12 per port, while a comparable managed Gigabit switch cost about $80 per port, he said.

“You can define quality-of-service paths within the network for different types of traffic,” using managed switches, Oppedahl notes, but “paying six times as much money per port makes it hard sometimes to justify the added expense.”

But cost is not the only overhead. To realize the added value of a managed switch, network administrators must know how to use the configuration and network-management tools they provide. Michael Fairchild, a program analyst at UCLA Particle Beam Physics Lab in Los Angeles, suggests that network managers need “a good understanding of Layer 2 network specs. … [Even] if you get a switch with a nice Web interface, you still need to understand [Layer 2] to some degree.”

Without any configuration, the majority of managed switches will operate like unmanaged switches right out of the box, Oppedahl notes. So IT managers who don’t have the network engineering skills to optimize their network should still buy managed switches, which they can learn to use at their own pace. “You just plug it in and connect the cables and that’s all,” Oppedahl says. “Then later, if you decide it is important to do so, you can actually use the management features.”

Among the products that have such management capabilities is the Linksys SRW2024, a rack-mounted, Layer 3 managed switch that lists for $469. The device features 24 10/100/1000BaseT Ethernet ports and two mini GBIC slots for fiber optic connection, the latter intended for interconnection with other Gig-E switches or network servers.

The forthcoming SRW2024P, available later this year, offers the same capabilities as the SRW2024 but adds 802.11af Power over Ethernet (PoE) support on all of the 10/100 ports — very useful for powering devices such as Web cams, IP telephones and wireless access points that are located too far from an AC power outlet to be plugged into the wall.

Administrators can manage the SRW2024 through the device’s serial console port to a dedicated management console or its built-in Web interface called WebView. WebView provides access to every feature available through the serial interface but is accessible remotely via the Web.

The SRW2024’s configuration features include enabling or disabling specific ports, setting port priority, routing packets based on protocol used and the ability to define up to 64 VLANs. VLANs allow you to segregate network traffic to prevent, for example, Windows shares belonging to users on one VLAN to be “seen” by the users on another VLAN.

Like other managed switches, the SRW2024 supports Simple Network Management Protocol (SNMP), which allows the device to be monitored by and integrated with other network management tools.

The SRW2024 also has a feature called IGMP Snooping that limits bandwidth-intensive traffic such as video streaming specifically to the users who requested it, so that such traffic does not degrade the performance seen by other users.

Although there is a significant premium on the price of managed switches compared to comparable unmanaged products, prices of managed switches are on the decline. So, even administrators who don’t need to manage their networks on a daily basis today can start building a manageable infrastructure for the future without breaking the bank.

 

Layer 2 Switches 10/100/1000
BaseT Ports
Mini-GBIC Fiber Slots Price Features
Cisco Catalyst 3560-24TS 24 2 $2,119.99 ARP support, auto-negotiation, auto-sensing per device, auto-uplink, DHCP support, IGMP snooping, IP-routing, IPv6 support, manageable, Power over Ethernet (PoE), trunking, VLAN support
Cisco Catalyst 3560G-24TS 24 4 $3,461.99 Auto-negotiation, full duplex capability, manageable
3Com SuperStack 3 3824 24 4 $1,786.99 Auto-negotiation, auto-sensing per device, DHCP support, flow control, Layer 2 switching, manageable, MDI/MDI-X switch, port mirroring, store and forward, VLAN support
D-Link DGS-3224TGR 24 4 $1,399 Flow control, manageable, VLAN support
Linksys SRW2024 Gigabit Switch with WebView 24 2 $469.99 Auto-negotiation, auto-uplink, flow control, store and forward
Layer 3 Switches  
3Com SuperStack 3 4924 24 Via optional expansion module only $3,542.99 Auto-negotiation, auto-sensing per device, full duplex capability, IGMP snooping, Layer 2 switching, Layer 3 switching, manageable, VLAN support
D-Link xStack DGS-3324SRi 24 8 $3,182.99 Auto-uplink, BOOTP support, Broadcast Storm Control, DHCP support, flow control, IGMP snooping, IP-routing, Layer 2 switching, Layer 3 switching, stackable, VLAN support
Netgear GSM7324 ProSafe 24 4 slots for optional ports $1,586.99 Auto-negotiation, auto-sensing per device, auto-uplink, BOOTP support, DHCP support, IGMP snooping, Layer 2 switching, Layer 3 switching, manageable, trunking, VLAN support

Source: CDW

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May 01 2006 Spice IT

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