Everything you should know about Cisco Routers.
Cisco is the largest brand that makes routers to route the various parts (LANs) of a network together. Cisco is the largest maker of this technology for business users where consumer grade equipment has a lot more competition. There is a wide variety of routers intended for a variety of purposes. For example a home or small office (SOHO) with 5 or fewer people is fine with a consumer grade router such as D-Link or LinkSys that normally costs $40-$80. While there are Cisco routers (800 series) intended for this role I strongly recommend using a consumer grade router or a PIX (a very wimpy firewall router) that is made for locations with under 40 people. Most work locations of any size put far more load on the router than a consumer route can handle. Most of the Cisco routers fit in this role specifically for offices ranging from 10-250 people. This normal sized location would be the 1600 - 2900 series of routers. There are routers designed for midsized locations such as a regional office or the headquarters of a moderately large firm. For the fortune 500 type firms there are some seriously powerful (and expensive) routers (7200 - 7600 series). Of course they are too big to forget about the friendly carriers (communication companies) who provide the internet and WAN connections. The carrier class models are numbered 100000 - 120000 and are powerful enough to manage traffic for their many customers. In the business networking hardware arena Cisco Systems owns the market with the vast majority of the market share. This is true for the switches as well, although other firms do provide a small amount of competition.
At the smaller offices a Cisco router is frequently used to connect to either the greater WAN or directly to the internet. Depending on the security requirements the Cisco router may or may not be suitable for a firewall. There is a feature called an access control list (ACL) that can be used to restrict traffic on any combination of source or destination ports and IP addresses. While this is fundamentally quite simple it can usually be used to filter out exactly what you want as long as you know what it is in terms of port numbers and packet flow. However this isn’t really designed for a firewall so many organizations offload that to another device designed for it. Another feature is network address translation (NAT). NAT takes IP addresses and changes the numbers as the packets go through it. A perfect reason to use this is to conserve the public IP (version 4) addresses most organizations don’t have enough of. There are many other features that these devices do as well such as Quality of Service (QoS) and Cisco discovery Protocol (CDP) which identifies what devices are directly connected to it if they run the protocol. Obviously the router has to do routing including some form of routing protocol. I personally like the proprietary EIGRP routing protocol the best. There are a lot of features in Cisco routers which makes the infrastructure much easier to manage.
Cisco routers and switches are the workhorse of most modern business networks in developed nations. It is possible to get these used, for a fraction of what they would have cost new. Unfortunately the very large ones don’t usually make their way to the sale block. They tend to get moved from the core of the network to someplace with less load on it to save the cost of buying a low-end new one. There is also a discount where used hardware can be exchanged for a discount on new hardware as a ploy to keep market share. Fortunately there is still plenty of used Cisco hardware on the market despite this. For example I recently took the time to review the used Cisco 1721 router product due to popular demand. There is a lot to any given Cisco router but that is part of networking and IT in general.
If you’re interested in further learning about this you can take an online course here or buy a book. I personally prefer the official CCNA certification book
If you want to learn more we also took the time to review the Cisco 2600 series of routers and a specific Router, the Cisco 2610. The 2610 is in the same series. We also looked at the Cisco Systems 1841 router as well which is one of the more popular modern models for network routing.