Routing protocols - data exchange between company branches

The information exchange within the computer networks between distant subnetworks i.e. company branches requires proper IP package routing configuration. Routing can be configured manually on the edge devices or one of the available routing protocols can be deployed. Manual configuration can only be used in very simple solutions where the network number is small and fixed in time. For other deployments it is advised to run one of the available protocols on the edge devices such as routers or firewalls. Properly-configured systems feature the variability of the package transmission route between subnetworks depending on the existing infrastructure conditions. In case of failure of one of the nodes the system automatically changes the package traffic route so that they reach their destination avoiding the damaged node. Keeping the work continuity is of crucial importance for most business applications. The above functionality is not reachable with manual routing configuration. Deploying our IT services we use one of the following solutions:

• RIP protocol – the protocol works on the basis of the distance vector that is to create a metric the amount of skips needed to reach the destination is used. The protocol features free convergence time or the convergence achievement time. It is used in small implementations up to 15 skips
• OSPF protocol – the protocol works on the basis of the connection status and contrary to RIP it enables creating multiple routes while still choosing the one with the lowest cost coming from the connection status. While implementing the OSPF protocol we operate on areas that are a set of networks that a certain protocol instance should work on. The feature of the OSPF protocol is the fact that every router in the area knows the full area topology and not just the information on the closest neighbors. The area exit points are served by the edge routers and aggregate metrics of the routes from and to a certain area. The area division during implementation is essential and we can use the division strategy based on the network location or functionality. The location-based division includes i.e. company branches that are considered autonomous areas from the OSPF point of view and the data exchange between them is possible though the edge routers. The division based on the network functionality means that during the implementation the OSPF will be configured in a way that the defined service traffic will take place in a certain way. For instance, the business data exchange between the branches can take place using one link and the VoIP telephony traffic using a separate link or a tunnel that is characterized by different parameters.
• EIGRP protocol – it is a closed protocol in comparison to the above two and it is implementation only on the CISCO devices. The algorithms used in EIGRP calculate the routing based on the connection status and distance vector. The router only stores the information on its closes neighbors and it does not possess full network topology as it happens in case pf OSPF. EIGRP protocol is well-integrated with devices and CISCO functionality and serves scenarios where the RIP and OSPF protocols fail.

Complicated scenarios may require the deployment of more than one routing protocol in a company network. In such case you should determine the cross-protocol data exchange rules on selected devices.