AirDesign Network and Computing Services

Network and Computing Services

Network Routers

Most enterprise organizations find that providing information to external customers and internal users in a timely and reliable manner is a significant challenge. Failure to meet this challenge can result in slow or unreliable information systems, which can lead to loss of business; conversely, fast and reliable systems can create significant competitive advantage. Information systems also need to adapt to changing requirements such as changes in product lines, office locations, customers’ purchasing habits, technology evolution, and acquisition of other organizations. In other words, organizations require agile information systems that can grow with time and not impose restraints on growth in the future.

At the heart of an information system is the computer network. Routers and switches are two critical components in the network; proper selection of these key devices helps ensure that the network provides fast and reliable service and can adapt to fast changing needs. High levels of reliability are also required as customers become more dependent on critical services such as online purchasing and rapid delivery of purchased products. Poor reliability can lead to loss of customer goodwill and potential business; conversely, good reliability helps ensure customer retention.

Higher returns are being demanded of the investments in IT infrastructure all the time; therefore, overall costs need to be controlled. A well-designed network, with properly placed routers and switches, can help reduce the operational costs and improve the availability, manageability, reliability, and utilization of expensive resources such as telephone links.

Router Operation

Routers operate at layer 3 of the OSI model. They effectively route traffic based on the destination IP address of the incoming data and link together devices on different IP networks. Routers provide the following two functions in the enterprise model:

• Connecting an internal LAN to the Internet through a WAN link.

• Linking the VLANs of the internal network; this enables users of one VLAN to access devices, such as servers, on another VLAN.

In the enterprise model, routers facing the Internet, typically known as edge or border routers, are standalone routers whereas the internal network routers are often integrated into switches. Routers embedded in switches provide layer 3 switching, which is functionally identical to standalone routing but is usually much faster because the router is directly attached to the switch rather than through a LAN link and the routing process operates in hardware at wire speed with no significant latency.

Classes are defined for routers that perform different tasks within the network, such as the perimeter routers facing the Internet, internal routers linking VLANs and smaller SBO routers. For each class of router, there may be manufacturers who provide the best router for that class, but they may not be able to provide the best possible router in the other classes. For example, at the SBO level there are a large number of manufacturers with good products at very competitive prices but most of these manufacturers may not satisfy the requirements for enterprise-level routers. The longevity of the manufacturer and the service level they can provide for problems
should also be considered. Smaller manufacturers may not survive at the SBO level, due to fierce competition and requirement of rapid technical support for business-critical solutions.

Although it may be tempting to get the best price in each class, cost of operation and maintenance must also be considered, for example, the cost of training the staff in different methods of configuring routers for each manufacturer. The total cost of ownership (TCO) should be reviewed and selecting one manufacturer to provide every
class of router required could prove to be a good solution in the long run. The same philosophy may be carried over to the selection of a single manufacturer for switches and all other network components, if possible.

Many enterprise-class routers provide virtual private network (VPN) capability, often as a software option, and although it is not necessarily used on every router in the network, it is a useful feature to include because it might become a requirement in the future.