7 steps to choosing a LAN switch

By Barbara Finer, Director of SMB Marketing, 3Com | Aug 1, 2008

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How does an SMB select a LAN switch to meet its business needs? Here are 7 deciding factors.

1. Number of ports
This is a function of the number of devices to be connected. Here is an easy way to identify how many switch ports you need:

• Count the number of user devices to be physically connected (by cables) on your LAN. Include PCs, laptops, printers, scanners, fax machines, IP video surveillance cameras and IP phones, etc. Remember to include those in conference rooms, reception areas, stock rooms or warehouses. Do not count wireless user devices; they connect to your LAN through a wireless access point, a network device that is included in the next bullet.
   
• Count the number of network devices to be physically connected on your LAN. Include routers, servers, wireless access points (each of which typically supports 20 or more wireless users), IP-PBXs and security devices such as firewalls, etc.
   
• Add ports to accommodate the growth that you anticipate in user and network devices within a few years. The sum of these numbers is the minimum number of switch ports you need; a rubric often used by technical experts is that the number of ports should be about 15% greater, to accommodate unforeseen needs. 3Com switches range from just a few ports to dozens of ports. Switches can often be connected to each another to multiply the number of available ports, and some higher-end switches can be "stacked" (combined to operate as a single entity, as if all their ports are in one very large switch).

2. Network speed
Speed is sometimes referred to as "bandwidth", which is the amount of digital data that can pass through a network connection in one second. Speed is measured in megabits (millions of bits) per second (Mbps).

Although the LAN connection capability in newer computers transfers data packets at close to 1000 Mbps (one Gigabit per second), many business LANs still transfer packet traffic at 10 Mbps or 100 Mbps.

A "10/100" LAN (which uses the 10BASE-T and 100BASE-TX Ethernet standards) supports both 10 Mbps and 100 Mbps ("Fast Ethernet" or "FE") speeds; the switch port matches the speed of the device connected to it. 10/100 LANs most often use twisted-pair (copper) cable, which allows the physical connection (between a switch and device) to be up to 100 meters long. Some 10/100 LANs also use fiber-optic cable, which allows connection lengths up to 2 kilometers.

Although 10 Mbps technology is over 25 years old, and 100 Mbps is over 10 years old, 10/100 LANs are fine for most data applications and many web and graphics applications. Most computers have a built-in Ethernet interface, a network interface card (NIC), for network connections. The NIC provides a unique media access control (MAC) address that enables the computer to send and receive data packets. In computers made prior to 2006, this interface
typically supports data transfers at 10 Mbps or 100 Mbps.

A Gigabit Ethernet LAN switch (which uses 1000BASE-T and/or 1000BASE-X standards) actually supports all three speeds-10/100/1000 Mbps-making it an ideal solution for computers of various ages. A business with a Gigabit LAN can use twisted-pair cable, which allows physical connections up to 100 meters long, or fiber-optic cable (1000BASE-X), which allows higher-quality data signals, greater speed and longer connection lengths. A switch that is equipped with a small form-factor plugable (SFP) optical transceiver can connect to either twisted-pair or fiber-optic cabling; this lets the SMB select the appropriate cabling for each link.

Gigabit connectivity is important for applications that use video, voice or complex digital images (including Web 2.0 applications). LAN ports that can deliver Gigabit speed are also best for connecting wireless devices that use the new high-performance IEEE 802.11n standard, because its data rate exceeds 100 Mbps.

The 3Com SMB switching portfolio offers extensive Gigabit and 10/100 port options. 3Com also offers enterprise-class switches with 10 Gigabit ports for larger networks and especially demanding applications such as video broadcasting, digital imaging, real-time financial transactions, large database access and data backup.

3. Switch management
This option determines the level of control you can have over your network, including the degree of security that your business wants for its networked data and communications. Managed switches offer more control; they also usually require more technical expertise. A network can be a mixture of managed and unmanaged switches.

Unmanaged switches are preconfigured entirely by the manufacturer based on industry-standard best practices for security and performance. This makes setup quick and easy, and reduces the price. You cannot use an unmanaged switch to segment one group from another or give priority to certain users; however, many 3Com unmanaged switches have a feature-support of the IEEE 802.1p standard-that can prioritize voice or video traffic higher than data traffic. Unmanaged switches are appropriate for many businesses. They satisfy most small business needs and can be quickly set up.

Managed switches provide control capabilities that can increase LAN security and performance, and let you segment traffic. For example, you could allow only certain employees to have access to your financial applications. You could also give some applications more bandwidth, or ensure that video and voice communications take priority over data.

Managed switches are typically required-for performance or security reasons-for business-critical applications such as Customer Relationship Management (CRM), Sales Force Automation (SFA), video surveillance, digital medical images and regulatory compliance, as well as for real-time applications such as audio/video streaming, distance learning, sales demos and VoIP. Many businesses that have multiple switches prefer the managed versions because they can configure them for consistency.

Some managed switches are "plug and play", meaning that they work out of the box using the manufacturer's configuration, without any need for technical expertise. You, your value-added reseller (VAR) or IT consultant can implement more of the switch's management capabilities later, as needed. Managing a switch beyond its plug-and-play settings requires some technical expertise, which can be obtained through the user guide, training, or a VAR.

You have several options in user-interface formats for switch management. Most SMBs prefer management that is "centralized" (vs. local) because it eliminates the need to physically travel to a switch to adjust, monitor or restart (reboot) it. IT staff can manage the switch remotely, using a number of user interfaces. Centralized management is available in these formats:

• Smart web-managed. This simplified format requires little or no expertise. It provides a select set of management features (such as configuration of port speed and traffic prioritization) for a price much lower than a fully managed switch. 3Com smart web-managed switches are plug-and-play; they also can be easily configured and operated without any need for a lot of technical expertise, using the built-in online help for each of the features. Web-managed switches are configured through a browser instead of a desktop utility; managing over the web can be secured by using HTTPS.
   
• Command-line interface (CLI) management. This type of management is convenient for quick set up and configuration, and provides more control than the web-managed format. It also requires more technical expertise.
   
• SNMP management. The Simple Network Management Protocol format offers the highest degree of control and the most comprehensive management, including automatic monitoring, reporting and correlation. It requires the most technical expertise. It is the basis of most network management applications software.

To find out whether you need switch management, and a brief tutorial on Layers 2/3/4, click here. 

4. Power over Ethernet
With this option, a switch port provides electrical power through the Ethernet cable to the attached device. Industry standard (IEEE 802.3af) PoE ports eliminate the need to install ("run") and operate separate electrical and network wiring: the inline power from a PoE switch port allows a PoE-compatible device to be placed anywhere there is a twisted-pair Ethernet cable (CAT5 or better). PoE switch ports are especially useful for connecting devices such as wireless access points, IP security cameras and IP phones.

PoE technology provides three major benefits:

• Flexibility. PoE increases the placement options for devices. For example, you can place a wireless access point up high on a wall or on the ceiling to get optimum RF coverage. All you need is one Ethernet cable, there's no need for another power source.
   
• Cost savings and time savings. You save the labor and materials costs-and delay-that otherwise would be incurred to have an electrician run more electrical wiring and install outlets. The lower voltage of PoE means that the twisted-pair Ethernet cabling can safely be installed in many locations by anyone. For example, you could quickly place and connect a video surveillance camera yourself.
   
• Non-Stop business. Devices (such as wireless access points, IP phones and IP cameras) that are connected to the switch's PoE ports can continue operating after a power failure if you have provided your PoE switch with redundant power circuits connected to an uninterruptible power supply. Different devices draw different amounts of power. IEEE 802.3af PoE switches offer a range of internal power supplies and number of PoE ports that let them support a variety of device power requirements and peak usage loads, up to 15.4 watts per port.

5. Voice-ready switching
By choosing a voice-ready switch, your business can run voice traffic over your LAN, and replace a traditional PBX or other telecommunications service, now or in the future.

With an IP telephony system and IP phones (wired or wireless phones that act like specialized computers), you can combine or "converge" your data and voice services into one secure digital network that interoperates with the public telephone system (PSTN) or a contracted VoIP service.

The benefits of doing this are cost savings, greater user and IT staff productivity, and improvements in customer service and sales. For example, convergence can reduce toll call charges and conferencing service charges, unify voicemail and email messaging, and allow a phone to be moved to another location or port and retain the same extension, owner recognition and settings. A business can also take advantage of communications applications such interactive voice response (IVR) and autodialing customers or employees from a database. Because voice traffic is delay-sensitive ("low latency"), the network switch must have technology features that make it voice-ready.

All 3Com switches that are voice-ready include:

• IEEE 802.1p QoS, which expedites and filters traffic. This standard allows the switch to reorder packets based on their priority value so that voice calls get adequate bandwidth to ensure voice clarity.

Some 3Com voice-ready switches also include these voice support features:

• DiffServ, DSCP and IEEE 802.1Q VLANs, which help to process voice and video traffic
   
• Auto-voice VLAN, which automatically detects and connects any standards-based IP phones and assigns VoIP traffic to a voice dedicated VLAN with appropriate QoS. This advanced feature optimizes delay-sensitive traffic

6. Form factor
Your choice of switch format depends on the layout of your work environment, your desire for quiet operation or physical security, and the number of switch ports you require. (Note: the following are the design differentiators, but both formats may be placed on a desk or in a rack.)

Desktop switches are designed to sit atop a desk or table. They are often the choice for conference rooms and smaller offices. They are generally smaller and quieter with a lower port count and cost than other switches.

Rack-mount switches are designed to be placed in a rack that is located in a wiring closet or other enclosed, physically secured room that typically houses other network devices, such as servers and telephony equipment. Rack-mount switches are often the choice of small and midsize businesses, as well as larger enterprises. Rack-mount switches often have fans, mounting brackets and a higher port count.

7. Requirements of your business
It may be last in the list, but this decision factor is certainly the most important when choosing a switch or other network equipment. You are the one who knows which of these product requirements are priorities for your business:

• Easy to set up and use, whether wired or wireless
• Secured against external and internal vulnerabilities
• Affordable without reducing quality
• Simple to integrate into your business
• High performance, whether with data, voice or video applications
• Reliable and backed by strong warranties and service
• Flexible and based on open standards, so you can take advantage of valuable new business technologies