Routing Information Protocol (RIP)

1. Routing Information Protocol or RIP is one of the first routings protocols to be created.

2. RIP is used in both Local Area Networks (LANs) and Wide Area Networks (WANs), and also runs on the Application layer of the OSI model.

3. There are multiple versions of RIP including RIPv1 and RIPv2. The original version or RIPv1 determines network paths based on the IP destination and the hop count of the journey.

4. RIPv1 interacts with the network by broadcasting its IP table to all routers connected to the network.

5. RIPv2 is a little more sophisticated than this and sends its routing table onto a multicast address. RIPv2 also uses authentication to keep data more secure and chooses a subnet mask and gateway for future traffic.

6. The main limitation of RIP is that it has a maximum hop count of 15 which makes it unsuitable for larger networks.

Open Shortest Path First (OSPF)

1. Open Shortest Path First or OSPF protocol is a link-state IGP that was tailor-made for IP networks using the Shortest Path First (SPF) algorithm.

2. The SPF routing algorithm is used to calculate the shortest path spanning tree to ensure efficient data transmission of packets.

3. OSPF routers maintain databases detailing information about the surrounding topology of the network. This database is filled with data taken from Link State Advertisements (LSAs) sent by other routers.

4. LSAs are packets that detail information about how many resources a given path would take.

5. OSPF also uses the Dijkstra algorithm to recalculate network paths when the topology changes. This protocol is also relatively secure as it can authenticate protocol changes to keep data secure.

6. It is used by many organizations because it’s scalable to large environments. Topology changes are tracked and OSPF can recalculate compromised packet routes if a previously-used route has been blocked.

Border Gateway Protocol (BGP)

1. Border Gateway Protocol or BGP is the routing protocol of the internet that is classified as a distance path vector protocol. BGP was designed to replace EGP with a decentralized approach to routing.

2. The BGP Best Path Selection Algorithm is used to select the best routes for data packet transfers. If you don’t have any custom settings then BGP will select routes with the shortest path to the destination.

3. However many administrators choose to change routing decisions to criteria in line with their needs.

4. The best routing path selection algorithm can be customized by changing the BGP cost community attribute. BGP can make routing decisions based on Factors such as weight, local preference, locally generated, AS_Path length, origin type, multi-exit discriminator, eBGP over iBGP, IGP metric, router ID, cluster list, and neighbor IP address.

5. BGP only sends updated router table data when something changes. As a result, there is no auto-discovery of topology changes which means that the user has to configure BGP manually.

6. In terms of security, the BGP protocol can be authenticated so that only approved routers can exchange data with each other.