Skip to content
Oct 7 / Greg

Cheap High Density Layer 2 Aggregation

Lets say we have a company that has several locations. They are about to all move into a new building, the majority of these users will be in a cube farm. All of the users will be within 280′ of your IDF. Each user is getting two ports, and you want them both to be hot for phone or for data. They will also be using Cisco IP phones, so we want PoE. This all works out to be about 298 ports. How would you go about aggregating all of these users?

Most people, I believe, will think, “Just put in a bunch of switches.” Indeed, this method works. There are some down sides to this. For one, you would require seven 48 port PoE switches. Each switch will run you $1850 for a 48 port 3560 PoE(WS-C3560-48PS-S) with a total of $12950. To save money you can get fourteen 24 port PoE 3550s (WS-C3550-24PWR-SMI) which cost $380 each for a total of $5320. On top of this you are looking at a beefy set of UPSs to power all of this gear. We want to have PoE power on our phones for at least 20 minutes in case of failure. The 3560s could be powered by a single triplite(SU6000RT4U
) which will run you around $3000, though the 3550s will most likely run you 2 UPSs. Beyond all of this, you have 7 or 14 switches that you have to interconnect, maintain and secure. The administrative burden gets somewhat high and should also be factored into the cost. Now, I’ll tell you what I would do in this situation.

I would choose to go with a larger chassis based system. A Cisco 6509 fits the bill quite well. My build is below:

  • WS-C6509 – chassis – $350
  • WS-C6K-9SLOT-FAN2 – fan tray – $299
  • 2 WS-CAC-2500W – power supplies – $410 each
  • 2 CAB-7513AC – power cables – $20 each
  • 7 WS-X6348-RJ45V – 48 port PoE line cards – $75 each
  • WS-C6X09-RACK & CK-CRSHELF – rack mount kit – $80

As for supervisor choice, you have a couple of options. I wanted to be able to do extensive layer 2 security, so I went with a sup32. If you aren’t concerned about securing layer 2, which you should be, you could simply use a sup2 which is MUCH cheaper.

  • WS-SUP32-GE-3B – sup32, my choice – $2500
  • OR
  • WS-X6K-S2U-MSFC2 – sup2, which I wouldn’t recommend because of it’s limited security – $530

So, for my system you are looking at a total of about $4650. You would also want the SU6000RT4U UPS which can maintain our chassis for the allotted 20 minutes. You’ve consolidated down to a single device, you’ve saved money and you now have a higher level of redundancy. If you wanted, you could slap a second supervisor in the chassis and you would bring the redundancy up even higher!

If you would like to know where I got my pricing, I used Teksavers and CablesAndKits which are both reputable distributors.

I have a following article that will show you how I plan to secure these devices, so keep checking back.

Leave a Comment