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Picking The Right Switch: A Buyer's Decision Tree

Purchasing a switch requires careful consideration of routing and performance needs, among other factors. Follow this decision tree to save money and avoid buyer's remorse.

When my company helps customers decide what type of switch they should consider, we weigh a variety of factors, from routing requirements and port speeds to manufacturer support. Careful planning before making a switch purchase will save you money by ensuring you don't wind up buying equipment that has functionality your organization doesn't need. At the same time, it can save you grief down the road by making sure you aren't left with switches that can’t expand their capabilities as your requirements change and grow.

Here is a decision tree you can use to help guide your switch purchase. The six decision points are listed from most to least influence in terms of choosing a model.

  1. Routing Requirements

    Routing requirements are a good place to start, since they usually dictate what series or line will be explored, and they can affect pricing dramatically.

    1. Yes, routing required
      1. Dynamic (Basic RIP, OSPF, BGP)
      2. Static (static and inter-VLAN routing)

    2. No routing required
  2. Port Speeds and Types

    When specifying needs with more detail, items a and b below are combined with d, and item a is combined with c. This tells us how many edge Power over Ethernet (PoE) and PoE+ ports we need, and at what speed. In addition, the number of both edge/primary and uplink ports and types is important. If you need 22-Gbit PoE ports for edge devices, but the same closet or data center switch needs to have also 8-Gbit Fiber SFP connections, it changes buying considerations.

    1. Speeds for primary ports
      1. 10/100
      2. Gigabit
      3. 10GbE
      4. 40GbE
      5. Mix
    2. Speeds for uplink ports
      1. Gigabit
      2. 10GbE
      3. 100GbE
      4. Mix
    3. Power requirements When exploring PoE, it’s important to use the manufacturer’s PoE planning guide for the switch models under consideration. Many switches will not support full PoE/PoE+ on all ports. For areas with high-power needs for VoIP phones or wireless APs, be sure to evaluate the maximum power draw per device and the estimated number of devices.
      1. Power
        1. PoE (IEEE 802.3af)
        2. PoE+ (IEEE 802.3at)
      2. None
    4. Number of primary ports
      1. 1-24
      2. 25-48
      3. 48-96
      4. 96+

    5. Number of fiber uplink ports Fiber optics and transceivers would be selected based on the fiber types, and distances and should be specified for each fiber uplink.
      1. 1-4
      2. 4-11
      3. 12-24
      4. 24+

    [There are five configurations a network administrator should apply to a newly provisioned switch or router. Get the checklist in "5 Basic Switch Settings You Must Know"]

  3. Performance Requirements

    Evaluate switch performance requirements for speed, position in the network and redundancy needs.

    1. Position in the network
      1. Edge
      2. Distribution
      3. Core
    2. Fabric speed Instead of detailing specific numbers, check the high and low ranges for the various managed edge and routing switches, and use that as a gauge. Ask your vendor for guidance here, as well. A device at the edge obviously has lower requirements for backplane and processing speeds than a distribution or routing device. Fabric speed is loosely based on the device’s position in the network if no other data is available.
    3. Redundancy Position in the network will likely again dictate the redundancy requirements. Most organizations increase redundancy as the devices get closer to the center or core. For distribution and core devices, as well as any critical intermediary or edge switches and switches supporting WAN devices, redundancy is highly recommended.

      1. Power redundancy
        1. Internal redundant
        2. External redundant
      2. Fabric redundancy
      3. Management redundancy
        1. Requires hitless failover?

  4. Environmental and Physical

    Environmental and physical specs may affect your selection of a particular switch model. In areas with unique environmental needs, and in tight spaces or older racks, the newer deep switch models may be precluded.

    1. Rack requirements, height and depth
    2. Power requirements, all power supplies
    3. Heat dissipation and thresholds
    4. Maximum noise restrictions

  5. Support

    Choose the support level for each device that gives you the support you need in the worst possible scenario, without overkill. Consider the switch's position in the network, and keep in mind that more critical systems will warrant more extensive support. Manufacturers such as HP are offering more advanced support options, including free lifetime support and software updates.

    1. Phone support options
      1. Business hours, 8x5 or 8x7
      2. 24-hour
    2. Onsite support options
      1. 4-hour onsite
      2. 8-hour onsite
      3. Other

    3. Hardware replacement options
      1. Next business day advance replacement
      2. Next business day replacement with Return Material Authorization (RMA) number first.
      3. Standard shipping advance replacement
      4. Standard shipping replacement, RMA first

    4. Software upgrades and firmware
      1. Paid, annually
      2. None
      3. Lifetime, included with product

    5. Duration
      1. 1-year
      2. 3-year
      3. 5-year
      4. Lifetime, included with product

  6. Manageability

    When specifying a brand, model or OS, consider other models and operating systems already in use. These systems are already managed and understood by the technical staff, and finding a comparable platform is helpful.

    1. What brands, models or Oss are currently in the network?
    2. What management software is currently in use?

Once you have gone through this decision tree, you should be ready to do some switch shopping. Are there any other factors your organization considers when preparing to buy a switch? What do you think are the most important factors? Post your comments below.

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