Getting Started with Cisco Router Hardware

Router Hardware

For many new network engineers it is a rare occurrence to have physical equipment to work with. Often network engineers could be working on Cisco equipment for years and still not have had the opportunity to physically set up a router. These days, with the different emulation and simulation options available, many certified Cisco network engineers don’t have to access this equipment to obtain the skills required to pass exams and be proficient. This article is written for those who are interested in getting some familiarity with the physical Cisco equipment. Here, the 2901 series router will be used as an example.

Most small to medium sized businesses utilize Cisco’s Integrated Service Routers (ISR). These routers are intended to be a general purpose, flexible option for a number of different environments that support a number of different capabilities from simple routing to VoIP and videoconferencing. The 2901 router that will be used as an example in this article is the successor to Cisco’s 2500, 2600 and 2800 series lines of routers. It is 1RU (Rack Unit) in size and is often referred to as a ‘pizza box’ router. The figure below shows a picture of the front and back of the 2901:

Router

Figure 1 – 2901 Front and Rear View

This article focuses on the hardware setup of a Cisco router. There are a number of different module options that are available for the 2901. The image in Figure 1 is of a 2901 without any additional modules installed. The first thing that any engineer must do with a new router (or new to them) is to configure and update it to meet the needs of its intended role in the network. To do this the engineer must connect a cable to the 2901 to access the console of the device. With older routers the only option when connecting to the console was via a custom rollover cable which was then used in combination with a RJ-45 to DB-9 or DB-25 converter which enabled a connection with a serial port on a PC. Since almost all newer PCs (including laptops) no longer have conventional serial ports many companies have developed USB to serial cable adapters which allow a connection to these older devices via a modern USB port. The 2901 has two different available methods of connection; via the older style RJ-45 port and a rollover cable OR via a direct mini-USB connection to the device.

The 2901 (and most new series devices) includes built-in Gigabit Ethernet interfaces (2) that can be used to connect the router to the network. The Gigabit Ethernet ports on routers are pinned the same as hosts/PC’s and do not require crossover Ethernet cables to connect to Switches. Some of the higher model routers also support small-form-factor pluggable (SFP) Gigabit Ethernet ports which enable the use of fiber directly into the device.

The 2901 is able to be used in a number of different physical locations. It is small enough to be used as a desktop device or it can be used in a 19 or 23 inch rack with the addition of rack brackets. The routers that are placed into racks are higher in model number than the 2901 and therefore are larger than 1RU.

Limitations

The 2901 is limited in the type of additional modules that it can utilize. In the rear of the 2901 there are four Enhanced High-Speed Interface Card (EHWICs) slots. The 2911, for example, also supports a single Service Module (SM) on top of supporting the same four EHWIC slots. Generally speaking the higher the router series number the more flexibility will exist on type of module supported.

Summary

Overall, the Cisco 2900 series (and its successors) have been built with flexibility in mind. The more recent versions of the routers (2800, 2900) have included support for many of the more common technologies seen in today’s environments (Voice, Video). The idea for this article came up because so many new network engineers never have access to real gear to physically set up and configure. Hopefully this will at least cover the basics of what an engineer would need to know before getting their hands on the equipment and playing with it to become familiar.

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