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murisonc
Asked: 2010-11-19 19:57:54 +0800 CST

Rear mount or front mount switches

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Where I work all the switches in a rack are mounted in the rear of the rack, but this presents a problem with hot isle cold isle cooling. The alternative is to mount the switches in the front of the rack with patch panels. But this wastes rack space because you are doubling or tripling the U's needed for a typical 48 port switch. We recently implemented hot isle cold isle in the server room leaving the switches to consume hot isle air. Do we need to suck it up and install pass through patch panels for each switch and sacrifice the rack space to get proper cooling? Maybe leave a 1U space above or below front mounted switches for cable routing to the rear of the rack where the server connections are located?

switch server-room rackspace

2 Answers

  1. Best Answer

    Most facilities I've seen just put the switches in the rear, and assume that they will find enough cool air to operate. Many switches are designed to operate in extended temps (they are often deployed in unconditioned wiring closets.) You may want to check with your vendor:

    Third party Vendors are addressing the switch issue for contained aisles. This product features plenums that provide cool air to the sides, and let hot air exit from the back of certain Cisco switches whether they are front or back mounted:

    http://www.wrightline.com/images/Products/Airflow%20Director%20Kit/Airflow%20Manager%20for%201U%20Switches.pdf

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  2. I generally suggest keeping the U above and below the switch open anyhow. As crazy as it sounds many vendors literally use stickers on their switches.

    I just the other day had to pull a NetGear GSM7352S switch for a client and try to get them an RMA on the unit. NetGear denied it because the serial # was partially scratched and the client did not know the full #.

    I pulled apart another old netgear switch and swapped power supplies - made it live and found the serial # - (go figure)/...

    In any event - it is always better to be safe than sorry. Stick with the airflow as needed. Use proper cable management - it really does make a huge difference.

    One suggestion would be to use something like a punch down block with very small short cat5/6/fiber cables going into the front of the switch - AND then run the cables to the back of the cabinet or rack.

    This is the most common setup we do for clients - and it works very well. I also suggest a good tool such as RackTables to help manage the punchdowns, cables, switches, etc...

    Bottom line - PLAN EVERYTHING Once you get to the point of having an entire 42U Rack filled - it is generally time to upgrade and move to a 2nd rack for heat and power issues...

    A good example of proper cable runs front to back is on this wiki. No clue who they are - but the setup is dead on

    https://wiki.appnexus.com/display/documentation/Racks

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