Layer 2 switches
Layer 2 switches<@VM>Affordable Layer 2 switches deliver data fast<@VM>Affordable Layer 2 switches deliver data fast (cont.)
Cost-effective traffic controls can bring your LAN up to speed
By J.B. Miles
Special to GCN
If your legacy Ethernet LANs are stretched to the breaking point under the weight of new users, servers and high-end applications, try replacing old Ethernet hubs with one or more 10/100-Mbps Ethernet switches.
All the switches in this guide are reasonably priced, flexible and suitable for running small networks or for connecting many small workgroups at larger sites. Unmanaged eight- or 16-port switches sell for as little as $20 per port, and many managed 16- or 24-port switches sell for as low as $100 per port.
Garrett Communications' Magnum switches come with eight to 24 10/100-Mbps ports and range in price from $599 to $1,199.
Unlike hubs, which share available bandwidth among attached devices, nonblocking switches provide dedicated 10- or 100-Mbps bandwidth to networked PCs, workstations and servers. And if you can't yet part with your existing hubs, you can use 10/100 switches to connect them for better network segmentation.
At the desktop, 10/100 switches are the best possible devices for connecting multiple users to the network at top speeds.
The accompanying chart lists 66 10/100 dual Ethernet workgroup switches from 26 manufacturers. They are equipped with eight, 16 or 24 auto-sensing 10/100 ports to determine the speed of attached devices and automatically configure the ports for 10-Mbps or 100-Mbps throughput. All can automatically negotiate between half- and full-duplex modes'the latter effectively creating dedicated 20-Mbps or 200-Mbps connections.
Most switches listed also provide shared or dedicated 10/100 uplinks to other switches or network backbones, and some even provide one or two dedicated Gigabit Ethernet links for especially heavy bandwidth requirements.
The products in this guide are Layer 2 switches, meaning they operate at the second, or data link, layer of the Open Systems Interconnection model. Their function is to check incoming network traffic, keep track of the physical addresses of all stations attached to their ports and forward traffic to specific station addresses according to the forwarding tables they have built. Layer 2 switches can deliver data at wire speeds because they don't have to examine individual data packets.
Layer 3 switches, also called routing or IP switches, perform both switching and routing tasks. Because they make heavy use of integrated circuits, specialized crossbar switching fabric, fast CPUs and other high-end components, they are expensive but well-suited to network backbone service.
But less expensive Layer 2 switches also provide an extensive range of features and options, making them cost-effective for managing traffic at the workgroup and small network levels.
Hewlett-Packard's ProCurve Switch 408 is an unmanaged, eight-port switch in a rackmount design. It is priced at $299.
Among their features and characteristics are:Auto-sensing.
A switch's auto-sensing capability means it can determine the speed of attached devices and automatically configure the ports for 10-Mbps or 100-Mbps throughput. It does this by reading the speed of the network adapter or network interface card attached to the networked PC or server.Auto-negotiation.
A switch's ability to automatically negotiate between half- and full-duplex modes is extremely useful for particularly bandwidth-hungry client applications, such as a remote computer-aided design and manufacturing workstation.
Full-duplex Fast Ethernet mode temporarily shuts down the Ethernet carrier-sense multiple-access with collision detection and loopback functions, allowing the switch to provide a theoretical bandwidth of 200 Mbps; that is, 100 Mbps in each direction.
But this capability comes at the expense of some of the collision detection features of half-duplex mode and should be only be used for isolated high-speed workstations where collision detection isn't required.Top aggregate bandwidth.
Aggregate bandwidth is the top theoretical speed limit of each switch and is related to the number of ports employed. Thus, the aggregate bandwidth of an eight-port switch running at 100 Mbps per port is 800 Mbps, while it's 1.6 Gbps for a 16-port switch.Store-and-forward.
The simplest switches operate as cut-through devices, meaning they only examine a packet's destination before forwarding it. More advanced store-and-forward switches analyze the entire packet before forwarding it. The tradeoff? Store-and-forwarding eliminates many traffic errors but takes longer than the cut-through technique.Unmanaged.
Workgroup switches may be managed or unmanaged. Unmanaged switches are plug-and-play devices and are a good match for small, flat networks with a mixture of 10-Mbps and 100-Mbps legacy devices. They can automatically learn network addresses and can handle both auto-sensing and auto-negotiation.
The best thing about them is their price. 3Com Corp.'s Office Connect Dual Speed Switch 8 is priced at $210, and Accton Technology Corp.'s popular CheetahSwitch Workgroup 3008A has been reduced to $199. D-Link Systems Inc.'s DSS8+ can be bought for as low as $87 from third-party vendors, and ARK Technologies' $75 CT2208D unmanaged switch is the cheapest I've seen'less than $10 per port.
Tips for buyers
' Choose the right path: Dual-speed 10/100-Mbps switches are the best hardware for migrating from Ethernet to Fast Ethernet.
' Remember that switches with one or more dedicated uplinks provide better expansion paths than those with shared-port uplinks.
' Consider a vendor with a large family of switch products if you know you'll be expanding your networks again.
' Buy a managed switch if you need to monitor and report on hubs, bridges, routers and other switches on the network.
' Plan carefully before making network moves and changes.
Managed switches, in the $1,000 and up price range, are more expensive because they perform more services. Network management features are important when remote switch management is required, or when several switches are linked as part of a more complex network than a LAN.
Products such as Allied Telesyn International Corp.'s $1,369, 16-port AT-8118 and all of Cisco Systems Inc.'s Catalyst 2900XL models'priced at $964 and up'come with proprietary management software. The software most often combines Simple Network Management Protocol and Remote Monitoring network management standards, with their own network management flavors and a little Web-based management tossed in.Scalability.
Simply adding users to a switch or connecting your switch to a network backbone switch is one way to scale your network upward. Rackmountable switches are more easily scalable than standalone desktop switches. Intel Corp.'s high-end switches with built-in Scalable Stacking Technology incorporate a scalable backplane into the switch stack. But the company's standalone Express 410T and 510T models listed here don't offer this feature.VLAN support.
Managed Layer 2 switches such as Accton's $785 CheetahSwitch Workgroup 3514F and all of IBM's 8275 series can support virtual LANs, either as a bundled or optional feature. A VLAN is a group of network resources or users on different network segments that communicate as if they were on the same wire.
Users can be linked by media access control addresses, IP addresses, network protocols or even the port numbers of a LAN switch into a virtual grouping that can share network resources and bandwidth.
VLANs are tied to Layer 2 technology, however, and as Layer 3 switches providing full Gigabit Ethernet wire-speed routing enter the market, they may disappear.Diagnostic port LEDs.
LED indicators at each switch port generally indicate the activity of the link, such as 10-Mbps or 100-Mbps bandwidth utilization or collision/full-duplex. An on/off switch LED light is included with virtually all switches.Media compatibility.
A big advantage to 100Base-T Fast Ethernet is that it runs over the same 10Base-T media that standard Ethernet uses. 100Base-TX'two pairs of data-grade Category 54 unshielded and shielded twisted-pair wiring'and 100Base-FX'two strands of multimode fiber'have emerged as the most popular cabling schemes in most wiring closets, so be sure that your switch supports them with appropriate connectors. The most popular media for Gigabit Ethernet uplinks is 1000Base-SX, which uses multimode fiber, but the more versatile, copper-based 1000Base-CX technology is coming on strong.J.B. Miles of Pahoa, Hawaii, writes about communications and computers.
|10/100-Mbpsports||Expansion||Configuration||Key switching features||Price|
|Accton Technology Corp.|
|Unmanaged||Eight||One shared 10/100|
|Desktop||Store-and-forward, full- and half-duplex, auto-negotiation, plug-and-play,self-learning configuration||$199 |
|Rackmount||Store-and-forward, full- and half-duplex, auto-negotiation, VLAN support||$785 |
|Allied Telesyn International Corp.|
|AT-8118-10||AT-View, SNMP, Telnet, Web-based||16 ||Two optional 10/100TX or 100FX uplink ports||Rackmount||Cut-through or store-and-forward, full- and half- duplex, auto-negotiation,automatic address learning||$1,369 |
|CT2208D/CT2208DI||Unmanaged||Eight||One shared MDI-IIuplink port||Desktop or rackmount||Store-and-forward, full- and half-duplex, auto-negotiation||$75|
|CT2216D||Unmanaged||16||Two shared MDI-IIuplink ports||Desktop or rackmount||Same||$185|
|Asante Technologies Inc.|
San Jose, Calif.
|FriendlyNet FS4008P||Unmanaged||Eight||One 10/100 uplink port||Desktop orrackmount||Store-and-forward, full- and half-duplex, auto-negotiation||$149|
|FriendlyNet FS4016P||Unmanaged||16||One 10/100 uplink port||Same||Same||$549|
|FriendlyNet FS4024P||Unmanaged||24||One 10/100 uplink port||Same||Same||$689|
|IntraSwitch 6224M||SNMP, Telnet,Web-based||24||Two MDI-II uplinkports||Rackmount||Same||$999|
|Cisco Systems Inc.|
San Jose, Calif.
|Catalyst 2912 XL||CiscoWorks, SNMP, Telnet, Cisco CGMP||12||N/A||Rackmount||Store-and-forward, full- and half-duplex, auto-negotiation, VLAN support||$964|
|Catalyst 2912MF XL ||Same||12||Two 10/100 uplinkports||Rackmount||Same||$1,001|
|Catalyst 2924 XL||Same||24||N/A||Rackmount||Same||$1,315|
|Catalyst 2924C XL ||Same||24||Two 100Base-FXports||Rackmount||Same||$1,927|
|Catalyst 2924M XL||Same||24||Two 10/100 uplinkports||Rackmount||Same||$1,614|
|PS2208 Pocket Switch||Unmanaged||Eight||One shared 10/100uplink port||Desktop||Store-and-forward, full- and half-duplex,auto-negotiation||$131|
|D-Link Systems Inc.|
|DSS 8+||Unmanaged||Eight||One MDI-II uplinkport||Desktop||Store-and-forward, full- and half-duplex, auto-negotiation, VLAN support||$87|
|DSS 16+||Unmanaged||16||Two MDI-II uplinkports||Desktop||Same||$297|
|Edimax Computer Co.|
Santa Clara, Calif.
|ES-3108P||Unmanaged||Eight||One shared 10/100uplink port||Rackmount||Store-and-forward, full- and half-duplex, auto-negotiation||$149|
|Farallon Communications Inc.|
San Leandro, Calif.
|Fast Starlet Palm Switch||Unmanaged||Eight||N/A||Desktop||Store-and-forward, full- and half-duplex, auto-negotiation||$153||Fast Starlet Switch 16||Unmanaged||16||One 100Base-FXport||Rackmount||Same||$378|
|Fast Starlet Switch 24||Unmanaged||24||Same||Rackmount||Same||$396|
|Garrett Communications Inc.|
|Magnum 4K8||Unmanaged||Eight||One or two optional 100Base-FX ports||Rackmount||Store-and-forward, full- and half-duplex, auto-negotiation||$599|
Palo Alto, Calif.
|ProCurve Switch 408||Unmanaged||Eight||One MDI/MDI-X port||Rackmount||Store-and-forward, full- and half-duplex, auto-negotiation||$229||ProCurve Switch 1600M||SNMP, Telnet, Web-based||16||One MDI/MDI-X port||Rackmount ||Same||$1,099|
|ProCurve Switch 2224||Unmanaged||24||One open transceiver slot||Rackmount||Same||$529|
|Vendor||Product||Managed/unmanaged||10/100-Mbps ports||Expansion||Configuration||Key switching features||Price|
|Hawking Technologies Inc.|
|Model PN636ES||Unmanaged||16||Two 10/100 uplink ports||Rackmount||Store-and-forward, full- and half-duplex, auto-negotiation||$321|
|8275 Series Model 318||SNMP, RMON, Web-based||16||1000Base-SX and 100Base-FXv port options||Desktop, rackmount||Store-and-forward, full- and half-duplex, auto-negotiation, VLAN support||$1,425||8275 Series Model 322||Optional||20||Same||Same||Same||$995|
|8275 Series Model 326||Optional||24||Same||Same||Same||$715 |
Santa Clara, Calif.
|Intel Express 410T Standalone Switch ||Intel Device View, SNMP, RMON, Web-based||16, 24||N/A||Rackmount||Store-and-forward, full- and half-duplex, auto-negotiation||$546 |
|Intel Express 510T Standalone Switch||Same||24||N/A||Rackmount||Same||$1,570 |
|Kingston Technology Co.|
Fountain Valley, Calif.
|KNS800/WG||Unmanaged||Eight||UTP port 5||Desktop||Store-and-forward, full- and half-duplex, auto-negotiation||$152 |
with Fiber Uplink
|Unmanaged||Eight||One 100Base-FX uplink port||Desktop||Store-and-forward, full- and half-duplex, auto-negotiation||$359||CenturySwitch 3508-01||Unmanaged||Eight||N/A||Desktop||Same||$539|
|DSSX12||Unmanaged||12||One 100Base-FX uplink port||Desktop||Store-and-forward, full- and half-duplex, auto-negotiation||$358||DSSX16||Unmanaged||16||Same||Desktop||Same||$449|
|Lucent Technologies Inc.|
Murray Hill, N.J.
|Cajun P120 Workgroup Switch||Cajun P120 Manager with SNMP, RMON, Lucent SMON||24||Optional 10/100, 100Base-FX or 1000Base-SX/LX ports||Desktop||Store-and-forward, full- and half-duplex, auto-negotiation||$1,755 GSA|
|Marconi Communications Corp.|
|Fore ES-1000||Unmanaged||22||Two optional 1000Base-SX/LX ports||Rackmount||Store-and-forward; expansion modules|
for addition of up to four 10/100 ports
|Network Peripherals Inc.|
|NuSwitch DS12A||SNMP, RMON, Telnet, Web-based, console port||12||Optional 100Base-FX uplink port||Rackmount||Store-and-forward, full- and half-duplex, auto-negotiation||$1,193 |
|NuSwitch DS16||Same||16||One 10/100 uplink port or optional 100Base-FX port||Rackmount||Same||$1,387 |
|Nortel Networks Corp.|
|BayStack 70-8T||Unmanaged||Eight||One MDI/MDI-X push-button option||Desktop||Store-and-forward, full- and half-duplex, |
|OvisLink Technologies Corp.|
City of Industry, Calif.
|Ether-FSH8TX||Unmanaged||Eight||N/A||Desktop||Store-and-forward, full- and half-duplex, auto-negotiation||$138||Ether-FSH16TX||Unmanaged||16||N/A||Desktop||Same||$375|
|EZ Switch II Model 6308TX||Unmanaged||Eight||One 10/100 uplink port||Desktop||Store-and-forward, |
full- and half-duplex, auto-negotiation, self-configuring
|TigerSwitch 10/100 Model SMC6912M||SMC EliteView, SNMP, RMON||12||Two 100Base-FX ports||Rackmount||Same||$986|
|TigerSwitch 10/100 Model SMC6924M||SMC EliteView, SNMP, RMON||24||Same||Rackmount||Same||$1,232 |
Santa Clara, Calif.
|OfficeConnect Dual Speed Switch 8||Unmanaged||Eight||One MDI/MDI-X uplink port||Desktop||Store-and-forward, full- and half-duplex, auto-negotiation||$210|
|OfficeConnect Dual Speed Switch 16||Unmanaged||16||One MDI/MDI-X uplink port||Desktop||Same||$390|
|Trendware International Inc.|
|TE100-S1616||Unmanaged||16||One shared MDI-II port, optional MDA 100Base-FX port||Rackmount||Store-and-forward, full- and half-duplex, |
|Unicom Electric Inc.|
Rowland Heights, Calif.
|Dyna Switch 16||Unmanaged||16||One fixed 10/100||Rackmount||Store-and-forward, full- and half-duplex, auto-negotiation, optional VLAN support||$349|
|Smart-Switch/24||SNMP, RMON||24||One fixed 10/100||Rackmount||Same||$1,575 |