Network Toolkit – When to use a console server

A console server is viewed far too often as a luxury item that can be justified. Console servers are useful at more than just data center locations. Sometimes you don’t know how much you may need or use one until the need arrives.

OpengearAt remote locations, having a device like can be a real lifesaver. When you have a remote office call in reporting their WAN connection is down, you can dial-up over a regular phone line (stealing the fax line should certainly be permissible in this type of situation) and get access to the site router to see if the router is the problem, if one or more WAN circuits are an issue or if the connection to the switch downstream of the router is the culprit. There are several vendors that offers these and they don’t have to break the bank. Opengear is one company that I have seen at Interop in the past has a small device called the ACM5000 (include graphic and hyperlink to www.opengear.com) that includes an analog modem and the ability to console into multiple devices locally. What got my attention on this box is that it doesn’t require the purchase of specially wired patch cables to connect the ACM5000 to the console port on a Cisco router.

For data center or lab rack situations, you have several options to choose from. If you are on a really really tight budget, you should be able to get a 2509 (8 device) or 2511 (16 device) router that is purpose-built for this application. You will need to purchase a “hydra” cable that has a high density connector at one end and terminates into 8 different RJ-45 that are already wired to plug into the console port of your Cisco router/switch/ASA/WLC. If you are using a 2511, you will need to purchase two of these cables. There are several sources available on eBay that wont set you back to much but you may find that the cost of the cable will come close to the cost of the 2509/2511.

If you have a device concentration higher than 8 or 16 or get approval to buy a “used” piece of gear, you have another option by using a NM-16A or NM-32A (the number indicates the number of devices that the network module supports. In this case, you would plug the module into a later generation of router that has a NM slot in it. If you happen to be using a 2900 series router, you would use a HWIC-8A or HWIC-16A. You will use a slightly different hydra cable but it is the same process here.

In a future post on this subject, I will share with you the configuration I use on one of the Console Servers I have on the lab. One thing that you will need to think about is securing the Console Server. On devices like this, I usually like to put them on an entirely separate Vlan to start with. Also restricting what systems are allowed to access the Vlan would be the next step that you should look at.

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