In computer networking, dynamic routing is a method of routing network traffic between networks and devices that allows routing paths to be determined automatically based on network conditions and traffic demands. This is in contrast to static routing, in which routing paths are predetermined and manually configured by an administrator.
Dynamic routing protocols discover and maintain routes to different destinations within a network or between networks. These protocols use various algorithms and metrics to determine the best route for a given data packet based on factors such as network congestion, link cost, and network distance.
There are several different dynamic routing protocols in use today, including the following:
OSPF (Open Shortest Path First)
Open Shortest Path First (OSPF) is a routing protocol used for Internet Protocol (IP) networks. It is a link-state protocol, which means that each router in an OSPF network maintains a database of the entire network topology and calculates the best path to each destination based on that information. OSPF is a routing protocol designed for use in Internet Protocol (IP) networks.
It is a link-state protocol, which means that each router in an OSPF network maintains a database of the entire network topology and calculates the best path to each destination based on that information. OSPF is designed to run on large, enterprise-level networks and is commonly used in Internet Service Provider (ISP) networks. It is known for its fast convergence and efficient use of network resources.
One of the key features of OSPF is that it is a classless routing protocol, which means that it supports variable length subnet masks (VLSMs) and can route traffic based on the subnet mask of a destination address. . This allows OSPF to support multiple network topologies and to address schemes within a single routing domain.
OSPF uses a hierarchical routing structure, dividing the entire network into areas. Each area is a collection of networks that share a standard area ID and are connected to a central routing device called an area border router (ABR). ABR is responsible for exchanging routing information between different areas and connecting them to the rest of the network.
Another essential aspect of OSPF is the concept of “neighborhood” relationships. OSPF routers establish and maintain relationships with their neighbours by exchanging hello messages and database information. These relationships allow routers to determine the best path to a destination and quickly converge on a new path if an existing path is unavailable.
BGP (Border Gateway Protocol)
Border Gateway Protocol (BGP) is a standard external gateway protocol designed to exchange routing and reachability information between autonomous systems (AS) on the Internet. BGP is used to build the Internet’s routing tables and is the glue that holds the Internet together.
BGP is designed to self-heal, so if one of the Internet’s backbone routers goes down, BGP will automatically route traffic around the failed router to keep it connected. BGP is an essential part of the Internet infrastructure and is used by Internet Service Providers (ISPs) to exchange routing information with each other.
BGP works by exchanging routing information between network routers. Each router maintains a routing table that lists all known networks, and the router uses this table to determine the best path to a destination network.
BGP routers exchange routing information with their neighbours using BGP messages. When a BGP router receives a BGP message from a neighbour, it updates its routing table with the information in the message.
BGP has several essential features that make it well-suited for use on the Internet. First, BGP is a path vector protocol which changes not only the destination network but also the path to that network. This allows BGP to choose the best path to a destination based on several factors, such as the shortest path, lowest cost, or highest availability.
Second, BGP is designed to be scalable, handling many routers and networks that make up the Internet. BGP can also handle changes in network topology quickly and efficiently, so it can adapt to changes in the Internet.
Finally, BGP is designed to be resilient and self-healing, so it can continue functioning even if part of the network goes down. If a router or link fails, BGP will automatically route traffic around the failed segment to keep it connected to the Internet.
EIGRP (Enhanced Interior Gateway Routing Protocol)
Enhanced Interior Gateway Routing Protocol (EIGRP) is a routing protocol used to exchange routing information between routers in a network. EIGRP is a hybrid protocol, meaning that it combines some of the characteristics of both distance vector and link-state routing protocols. It was developed by Cisco Systems and is proprietary to them.
EIGRP uses a combination of distance vector and link-state algorithms to determine the best path to a destination. It maintains a routing table that contains the best paths to various destinations and sends updates to its neighbours to inform them of changes in the network.
EIGRP uses a metric called the composite metric, which takes into account factors such as bandwidth, delay, reliability, and load to determine the best path.
EIGRP is considered to be a very efficient and stable routing protocol, and it is widely used in enterprise networks. It is also used in some service provider networks, although it is less common in this environment due to its proprietary nature.
EIGRP has several features that make it a popular choice for enterprise networks:
- Fast convergence: EIGRP can quickly adapt to changes in the network and find new routes to a destination if the primary path becomes unavailable. This allows it to maintain stable and reliable communication in the network.
- Low overhead: EIGRP uses a minimal amount of network resources, making it efficient and scalable.
- Support for multiple protocols: EIGRP can carry routing information for multiple network layer protocols, including IPv4, IPv6, and AppleTalk.
- Support for VLSM: EIGRP supports Variable Length Subnet Masks (VLSM), which allows it to route traffic between subnets of different sizes.
- Support for load balancing: EIGRP can load balance traffic over multiple paths to a destination, providing additional network redundancy.
These are some examples of dynamic routing protocols. There are many others in use, each with its unique features and capabilities.