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luxerama
Asked: 2011-01-25 09:19:30 +0800 CST

Network setup (is there any penalty for having multiple switches)

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My expertise in networking are limited thus I'd be grateful for your opinion on the following.

We will soon be moving into a new office, the question now is how to best rig up the network. To illustrate I have created some v. crud diagrams of two different options.

Network Diagrams

Option one would only require one switch in the comms room however it would mean that we would have to run a network cable (approx 20m) per pc through the sealing.

Option two would require multiple switches, one in the comms room, and one for each row of tables in the office.

Does anyone know whether one of the two options has any great advantages over the other?

networking network-design

4 Answers

  1. Best Answer

    I'd prefer option 3 ! Its neither 1 or 2 really, more a hybrid.

    What happens in option 2 is your company gets bigger and you end up with many many little cheapo switches under every block of desks. Then you find looped cables take out your network when some joker starts messing with the wires. You'll also spend you whole life on your knees messing with switches in a hiddeous pile of wires under people's desks.

    Option 1 take a little more thought, but is better overall, however you normally dont run cables from pc's to the server room in one hit. What you likely want is:

    A group of cat ports under desks (typically under the suspended floor if you have one) - 3 per person is usually enough to allow for voip phones and laptops

    Each of those ports under a desk is wired to a patch panel in a cabinet (one per floor say)

    Also in cabinet is the switch(es), you patch those floor ports into live switch ports as needed. Make sure you label up the patch panel fully !

    Uplink the switch(es) to the server room.

    I've seen this done several times and it worked out really well. When people join you just wire in the floor ports to the switch, and it makes it easy in the future if you migrate to VoIP phones or want to segregate the network, and when people move desks.

    The key is to make sure you have a fair number of ports (employees x 3 say) all wired to the patch panel. That way you can pick and choose what you make live, and avoid the hundred mini switch nightmare of option 2.

    In your case you may need to alter this slightly to take the cables up and into the roof space, but its one of those jobs where a weekend of work will make your life a million times easier.

    I've also had the "everyone has a switch under the desk" situation (not by choice) and you'd be amazed how bad the wiring nests get after being kicked by feet for a few months.

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  2. The second option is easier to implement and to manage, but it has an obvious problem: the link between the two switches is a bottleneck that could severely limit the total throughput between the two network segments. Many high-end switches (such as Cisco ones) have dedicated ports for this role, with greater speeds than the other ones; they also often let you bind together two or more ports, creating a single logical link with more bandwidth.

    Other than bandwidth (and cost) considerations, the presence of an additional switch doesn't usually create any problem by itself.

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  3. If you're small and plan to stay small (<10 stations) then there no real disadvantage either way. But if you plan on any sort of growth I'd recommend option one.

    Most offices keep all their switching equipment in the comm room for the following reasons:

    1. Easier to manage their physical state. (not kicked, accidentally unplugged, dusty, hot, etc..)
    2. You can easily move/change connections to a different switching path from a centralized location. (Lab Network vs. Production, spanning tree, topology changes)
    3. Fairness in forwarding. If you are flat switching, then whoever shares a switch with the server will have a lion's share of the bandwidth.
    4. Aggregation of ports. If you're buying 24 port switches and your table rows only have 16 people that's a lot of unused ports. If you have all your switches in one place you only need one spot with excess capacity.

    Other thoughts:

    Consider buying managed switches. The prices are very low these days, and if you need to make complicated changes later it will be easier.

    If you've got more than 10 stations, consider having a network/wiring tech come out to do this setup. Chasing network/physical layer issues is not fun, and definately something to do right the first time.

    Before running wire in the ceiling check local fire codes. Cat-5E wire can create toxic fumes when it burns. If your ceiling is part of the ventilation system you're probably required to use plenum rated cable. In some cases fire codes require that all cables be run through conduit.

    Edit: Sirex is right. Use patch panels/jacks to wire everything down. Don't just run straight cable through the ceiling without terminating it correctly at each end. I assumed this is what you would do anyway.

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  4. I would prefer option two, because it greatly simplifies cabling in cost of insignificant delay to forward frame from one switch to another.

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