Routing Protocol for Computer network from kurose and ross

Useful for computer network

1. Routing Protocol

2. Before knowing RPs, we need to know Forwarding Table A forwarding table is consulted by a router to decide which outbound link to use for a given packet, based on the packet's destination address Forwarding tables are crucial for routers to quickly decide where to send incoming packets. They enable efficient and accurate packet delivery across the network.

3. Routing Protocol : Definition A routing protocol is a key component of computer networks, responsible for automatically setting the forwarding tables in routers. These protocols determine the best paths for packets to travel from source to destination, enabling efficient data transmission across the network

4. Routing Protocol: Classification (Based on the scope of operation) Intra-AS routing protocols These protocols, like OSPF, operate within a single Autonomous System (AS), typically an ISP's network. They focus on finding the best paths within the AS, considering factors like bandwidth, delay, and policy Inter-AS routing protocols Protocols like BGP (Border Gateway Protocol) handle routing between different ASs, essentially connecting the entire Internet. They deal with issues like policy, reachability, and economics, allowing ASs to control how their traffic flows and interacts with other ASs

5. Routing Protocol: Classification (Based on the scope of operation) Static routing protocols Routes are configured manually and change infrequently, often requiring human intervention to update. Static routing is suitable for simple networks or specific situations where precise control over paths is needed Dynamic routing protocols These protocols adapt to changes in the network topology or traffic conditions by automatically updating routes. Dynamic routing protocols like OSPF and RIP exchange routing information periodically or when changes occur, enabling them to adjust to network fluctuations and maintain connectivity

6. Routing Protocol: Classification (Based on whether the protocol is load-sensitive or insensitive) Load-sensitive routing protocols These protocols consider the current level of congestion on links when calculating routes. Early ARPAnet routing protocols were load-sensitive, but challenges arose in their implementation Load-insensitive routing protocols Most current internet routing protocols, including RIP, OSPF, and BGP, do not explicitly factor in link congestion when determining paths. This simplification makes them easier to manage and less prone to instability

7. Routing Protocol: Classification (Based on the algorithm used for route calculation) Link-state routing protocols These protocols, such as OSPF (Open Shortest Path First), require each router to have a complete network topology map. Routers exchange link-state information with all other routers in the autonomous system. This allows routers to build a complete map of the network and independently calculate the best paths using Dijkstra's algorithm. Link-state protocols are generally considered more scalable and converge faster than distance-vector protocols Distance-vector routing protocols Protocols like RIP (Routing Information Protocol) fall under this category. They operate by having each router maintain a table of distances to all destinations in the network. Routers exchange this distance information with their neighbors, allowing them to update their tables and learn about new routes. Distance-vector protocols are simpler to implement but can suffer from issues like slow convergence and the "count to infinity" problem

8. Dijkstra’s link-state routing algorithm centralized: network topology, link costs known to all nodes accomplished via “ link state broadcast” all nodes have same info computes least cost paths from one node (“ source”) to all other nodes gives forwarding table for that node iterative: after k iterations, know least cost path to k destinations