Routing involves finding optimal routes between networks in a topology. Determining the best path requires defining the criteria and metrics.
What is Routing in Computer Networks?
The routing function determines paths for groups of devices based on configuration. It identifies the best way to use the table entries. The configured addresses help establish connectivity between devices. Additionally, proximity among similar addresses influences the routing decisions.
In large networks, structured addressing surpasses unstructured addressing due to its efficiency. Routing plays a fundamental role in managing Internet traffic. Meanwhile, bridging remains popular for local area networks.
Routing Parameters
Network Metric
The network metric is the hops required to go from one point to the destination. Initially, this value is 1 for all connections and increases by one as the LAN grows.
Another metric type is measuring latency between neighboring nodes in units of time. This latency varies based on network traffic, not constant network values.
The network metric values mentioned above determine the best route. They vary with protocols and measurement values for target LANs.
When a router has many paths to the target network, various methods help determine the closest and optimal way. Sometimes, the router may prefer a more relative path, selecting the way with the optimal bandwidth for the best outcome.
Depending on LAN protocols, metric calculation systems may vary in finding optimal routes.
The Best Way
Different structures and protocols determine the best way. Typically, the basis for this is the delay and minimum hop count between nodes.
Selecting the best path relies on the shortest way to reach the destination. Generally, a network’s distance or cost refers to the link’s quality based on the defined metric.
Virtual Circuit and Datagram Networks
The packet-switched network operates in a virtual circuit model. The way function typically creates a path throughout the lifetime of this virtual circuit. In this case, the session manages the routing process between LANs.
A network in datagram mode doesn’t guarantee regular packet transmission. Nodes can change the terms of sending each packet. The algorithm discovers the optimal way for a new LAN. In case of topology changes, we create an alternative method.
Classification of Routing Algorithms
Static
Manually configured static routes do not consider subnet state. Administrators can delete or change path tables, resulting in the deletion of these routes.
Static routes cannot automatically adjust when there are changes in the network or if there is a failure. The algorithm for static routes can be complex, and it takes a while to figure out the best path. However, static routes can perform faster if we don’t need to calculate the best way.
Dynamic
Subnets adapt to subnet changes like dynamic route changes or increased latency. Moreover, they respond to topology failures and ensure rapid convergence within the network.
We divide this type into three groups based on where we decide things for the network and share information. These groups are called central adaptability, distributed adaptability, and isolated adaptability.
In the central adaptive structure, all nodes in the network are essential. These nodes gather information and data from other nodes. They use this information to figure out the best path for communication. It helps make sure that messages travel quickly and smoothly within the network. The disadvantage of this method is that it consumes plenty of resources from the web.
The purpose of the distributed adaptive structure is to run an algorithm on all nodes. Each node relies on information and continuously updates based on its data. Consequently, the LAN maintains efficient communication.
Distance-vector and link-state algorithms are prevalent for routing on the Internet. They help networks adapt by using a dynamic structure for routing information.
In an isolated structure, the method used to adapt is simple. It handles the changing state of the LAN. This method utilizes each node’s local database information for traffic or topology changes.
Dynamic Route with Distributed Algorithms
Distributed algorithms and route operations rely on the dynamic model’s structure. Furthermore, these algorithms use up-to-date network data for rapid convergence. Additionally, route tables adjust to network changes and heavy traffic.
We divide these types into two main groups based on this type of operation.
1. Distance Vector
The distance vector uses the Bellman-Ford algorithm. It finds the lowest-cost route using an indirect search method. Then, it sends the packet to its destination efficiently. It is a control packet that calculates the distance to nodes about a network node.
Each node sends distances to neighbors through a packet. Neighbors examine and update their tables based on this information. It allows for comparisons with existing data. Examples of distance vector protocols include RIPv1 and v2, IGRP, and EIGRP.
2. Link State
The link-state network structure relies on each node’s topology and latency values. It utilizes the Dijkstra algorithm for efficient routing. Examples of this type are OSPF and IS-IS protocols.
Autonomous Systems
An autonomous system (AS) consists of IP networks and routers on the Internet. These LANs and routers are under the control of the same entity. Moreover, they have a similar route policy in place for efficient routing.
We base the classification of different protocols on a router’s relationship to an autonomous system.
Ad Hoc Protocols
Networks with little or no infrastructure use these protocols.
Interior Gateway Protocols
Systems that transfer tables within a single autonomous system use interior gateway protocols. For example;
- IGRP (Interior Gateway Routing Protocol)
- EIGRP (Enhanced Interior Gateway Routing Protocol)
- OSPF (Open Shortest Path First)
- RIP (Routing Information Protocol)
- IS-IS (Intermediate System to Intermediate System)
Exterior Gateway Protocols
Systems that exchange tables between different autonomous systems use exterior gateway protocols. For example;
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