Layer 3 switches take the fast route
Layer 3 switches take the fast route<@VM>These 19 switches can route a network toward better performance
This class of switches enhances routing technology to avoid bottlenecks and keep your network traffic at maximum speedBY J. B. MILES
| SPECIAL TO GCN
In the best of all possible networks, large volumes of data flow from high-end workstations and data centers, and e-mail messages with complex multimedia attachments flit about effortlessly, all without bringing transmissions to a crawl.
That day is coming, as networking technologies improve, but it won't be tomorrow. In the meantime, the best most organizations can afford is a mix of 10-Mbps Ethernet and 100-Mbps Fast Ethernet service to the desktop PC, with one or two Gigabit Ethernet backbone links.
size="2" color="#FF0000">Extreme Networks' Summit24 and Summit48 provide advanced Layer 3 switching with IP and IPX protocols. They range in price from $3,495 to $5,995.
Ethernet has dug in as the world's most popular network topology for good reasons. Using small servers and inexpensive hubs, many organizations can get by with shared 10-Mbps or 100-Mbps bandwidth to the desktop for noncritical applications such as departmental e-mail.
For more critical applications, 10/100-Mbps Ethernet switches can provide dedicated bandwidth to users at wire speed. Meanwhile, 1-Gpbs Gigabit Ethernet switches can be used effectively to connect high-speed servers or link to network backbones.
What is it? A Layer 3 switch operates at the network layer of the OSI model, combining fast Layer 2 switching with routing functions normally handled by independent, slower routers. 10/100 Fast Ethernet switches provide 10-Mbps Ethernet or 100-Mbps Fast Ethernet service.
What are the benefits? Layer 3 Fast Ethernet switches keep data moving while avoiding bottlenecks. Once installed, an Ethernet topology also provides an easy, inexpensive upgrade path to faster speeds, such as Gigabit Ethernet and 10-Gigabit Ethernet.
What are the drawbacks? The switch market currently is in flux'with buyouts, mergers and takeovers'which could affect your system down the road.
Price? Per-port 10/100 Layer 3 switch prices generally range from about $150 to $500 or more, depending on the features you select.
8Must-know info? Layer 3 Fast Ethernet switches provide fast, flexible, scalable and easily managed service at a price that is low compared with the other elements of a network.
This guide features 10/100 Layer 3 Fast Ethernet switches designed mainly to provide dedicated high-speed bandwidth and routing capabilities to multiple workgroups at the edges of large networks.
This category of hardware barely existed a year ago. Limited numbers of Layer 3 Gigabit Ethernet switches with a few 10/100Base-T ports were available. But there were very few Layer 3 10/100 switches for workgroups and small departments.A growing market
Things are changing. In a search of more than 70 switch manufacturer Web sites, I found 18 companies that make Layer 3 switches targeted to the dedicated 10/100 Fast Ethernet market. Most also make Layer 3 Gigabit Ethernet products.
I selected 10/100 switches that come in eight-, 12-, 16- and 24-port configurations for workgroup service. Many of the products listed are modular or stackable, and can provide switching for up to 96 ports. Most also offer one or two optional or built-in slots for Gigabit Ethernet backbone links or 100Base-FX fiber links.
The accompanying chart lists only a sampling of available switches from each manufacturer. Check the companies' Web sites to find other switches in the Layer 3 category; one of them might best meet your requirements.
The real benefits in Layer 3 switches come in the routing of data. Layer 2 switches can deliver dedicated data to any station on the network at wire speeds because they don't have to handle individual data packets and route them to their destinations'that job, by definition, belongs to network routers.
|Before you buy, make sure|
these features are standard
Auto-negotiation. A switch should have the ability to negotiate between half-duplex and full-duplex modes. Full-duplex, which allows bidirectional transmission of data, theoretically doubles of the usual throughput'for instance, from 100 Mbps to 200 Mbps.
Auto-sensing. It should be able to determine the speed of attached 10-Mbps or 100-Mbps devices and set port speeds accordingly.
Backup power. Redundant power supplies or uninterruptible power supply devices are provided as options with most Layer 3 switches.
Broadcast traffic control. Broadcast throttling detects excessive packets sent by a failed or improperly configured network device and prevents them from overwhelming the network.
Class of Service. CoS is a standard IEEE 802.1d method for prioritizing various traffic types to allow users to specify high-priority applications. Most Layer 3 switches also support layers 4 through 7 of the OSI model to ensure enhanced traffic control.
Fault tolerance. Dual CPUs, redundant cooling fans and other components can be provided as options for some Layer 3 switches serving in mission-critical operations.
Flow control. By monitoring the port activity, a switch can eliminate dropped packets on congested ports.
Hot-swappabilty. You should be able to swap interface modules holding various port configurations without shutting down the switch.
IP firewall. This feature, often available as a software option on switches, protects your network against intruders coming through the Internet.
Management. Most Layer 3 switches come with proprietary management software based on Simple Network Management Protocol and Remote Management protocols. In most cases, Microsoft Windows and Web-based management interfaces are also provided.
Multicast filtering. This feature allows the automatic configuration of filters for IP multicast traffic, such as video and audio broadcasts. It allows multimedia applications to be efficiently delivered to workgroups.
Multiprotocol support. High-end switches come with options for handling protocols in addition to IP and Novell IPX, such as AppleTalk, IBM SNA and others.
Policy-based broadcast management. The ability to broadcast according to specific user-defined domains, such as IP subnets, protocol types or Medium Access Control addresses, reduces overall traffic loads by preventing the need for data to be sent to every station on the network. It also supports virtual LANs.
Port trunking. Treating multiple parallel links as one backbone pipe provides network redundancy. If any link fails, traffic is re-routed to other links.
Redundant uplinks. Multiple uplink ports on switches provide alternate paths into the network in case one link fails.
Scalability. Stackable switches can multiply the total number of available ports. A modular switch can add extra modules for the same purpose or add support for different network protocols.
Spanning tree support. The spanning tree protocol protects against network loops and provides redundant network paths.
But because most of a LAN's legacy routers are software-based, they can't keep up with Layer 2 switch speeds. Traffic bottlenecks often occur wherever they are installed.
Layer 3 switches bypass this problem by combining the raw throughput speeds of Layer 2 switches with advanced routing technology. They are built around hardware-based, application-specific integrated circuits and specialized switching fabrics, which enable them to handle packet forwarding much faster than can software-based routers.
Most Layer 3 switches employ software protocols running in the background over built-in RISC processors to help them perform routing calculations at similar, lightning speeds.
Some advanced routing protocols, more commonly known by their acronyms, include Routing Information Protocol (RIP and RIP2), Open Shortest Path First (OSPF), Dynamic Host Configuration Protocol (DHCP) and Bootstrap Protocol (BootP), and multicast protocols such as Distance Vector Multicast Routing Protocol (DVMRP) and Internet Group Management Protocol (IGMP).Problem solvers
Layer 3 switches not only overcome slow packet routing, they also alleviate common problems encountered with flat Layer 2 networks, such as broadcast storms and address limitations. As a result, managers can configure and manage large network segments more easily without having to create as many subnets'using traditional routers'as they did in the past.
More of the management capabilities of layers 4 through 7 currently are being built into the newest Layer 3 switches.
Layer 4 is the transport layer of the Open Systems Interconnect model and is used with the other top layers of the OSI model to help prioritize traffic types and allow users to specify applications that should receive high priority. For example, a switch with Layer 4 capability could set a lower priority for departmental e-mail than for mission-critical data from a high-end system.
Beside their terrific performance ratings, the best thing about Layer 3 switches is their price relative to other network gear. Per-port Layer 3 switch prices range from a low of about $150 per 10/100 port to $500 or more depending on the features'with one or two Gigabit Ethernet slots often included.J.B. Miles of Pahoa, Hawaii, writes about communications and computers. E-mail him at [email protected].
|Vendor||Product||10/100 ports||VLAN and Web configuration support||Price|
Alcatel USA Inc.
OmniStack 6000 Series
24 to 96
Stackable; supports up to four Gigabit Ethernet or eight FE fiber slots; features IP multicast switching, optional ATM support, optional firewall software; allows SMTP and RMON network management
$8,045 to $9,995
Allied Telesyn International Corp.
Rapier Layer 3 Series
16, 24, 48
Features two Gigabit Ethernet slots; VLAN tagging; RIP, RIP2 and OSPF routing; optional software for IPX and AppleTalk; plug-in cards for WAN connectivity, and SNMP, RMON Telnet and command-line interface for management
$2,995 to $6,495
San Jose, Calif.
Features one Gigabit Ethernet slot; simultaneous Layer 2, 3, 4, 7 switching; VLAN support; SNMP and RMON management; load balancing; hot-standby, and Web-based user interface
24 to 32
Has two expansion slots on Model 5048 for Gigabit Ethernet; FE fiber or ATM slots; full redundancy of all components; load balancing, and IP, IPX and AppleTalk routing
$9,216 to $15,312
Cisco Systems Inc.
San Jose, Calif.
Has two Gigabit Ethernet slots; RIP and RIP2 routing; VLAN support; quality-of-service (QoS) support; SNMP and RMON management, and optional redundant power supply
SGX89216 Layer 3
Has two Gigabit Ethernet slots; VLAN support; SNMP and RMON management; Web-based user interface, and optional T1/E1 WAN module
price not available
8 or 16
Has 16 10/100 slots (900CC) or eight 1/100 slots and one Gigabit Ethernet slot (900CG); flow control;SNMP clearVISN management; VLAN support, and hot-swappable modules
Extreme Networks Inc.
Santa Clara, Calif.
24 or 48
Has one Gigabit Ethernet slot; basic and advanced Layer 3 switching with IP and IPX protocols; policy-based QoS; fault-tolerance; and HTTP, SNMP
RMON and command-line interface management
$3,495 to $5,995
Foundry Networks Inc.
San Jose, Calif.
FastIron Workgroup Switch
Stackable; has optional Gigabit Ethernet ports; QoS support; IP multicast support; VLAN support; fail-safe support; SNMP and RMON management, and multiple security options
Palo Alto, Calif.
Procurve Routing Switch 9304m
8 to 72
Modular, with support for up to 72 10/100 or 32 Gigabit Ethernet slots, or a combination; has IP and IPX routing, policy-based VLAN support, hot-swappable modules and automatic failover
Santa Clara, Calif.
Express 550T/F Switch
Stackable, with copper (Model T) and fiber (Model F)port support; integrated IP and IPX routing; QoS support; advanced flow control; VLAN support, and SNMP, RMON and Web-based management
$3,195 to $7,995
Lucent Technologies Inc.
Murray Hill, N.J.
Cajun P333R Routing Switch
Stackable, multilayer IP routing, expansion slot for 16 additional 10/100, two FE fiber or two GB Ethernet ports, QoS, RMON support
Has 6-slot modular chassis with support for up to 62 10/100, 16 Gigabit Ethernet or 32 FE fiber ports; RIP and RIP 2 routing, and is pre-configured either as a Layer 2 switch or Layer 3 router
Nortel Networks Corp.
Passport 1100 Routing Switch
Has two field-installable modules for Gigabit Ethernet or FE fiber ports; IP and IPX protocols; MultiLink trunking; IGPM multicast filtering; QoS support; VLAN support, and a Web-based configuration
Plaintree Systems Inc.
Has two optional Gigabit Ethernet or FE fiber slots; IP routing and IGPM multicast filtering; QoS support; VLAN support; SNMP and RMON management; HTTP HTML and Java support, and selectable security
SMC Networks Inc.
Has two optional FE fiber slots; flow control; VLAN support; optional redundant power unit, and SNMP, RMON and Telnet management
Telco Systems Inc.
16, 24, 32
Modular and stackable; has optional fiber or copper ports; one Gigabit Ethernet slot; VLAN support; a large variety of interface modules, and SNMP and RMON management
$4,592 to $5,650
Santa Clara, Calif.
Layer 3 Module
Adds Layer 3 routing capabilities to 3Com's SuperStack II 1100, 3300 and 3300 FX switches
$1,300 to $2,000
Has one or two optional Gigabit Ethernet slots; RIP and RIP2 routing; flow control; policy-based VLAN support; user-definable packet filters; QoS support, and SNMP and RMON management
$5,000 to $9,975