Difference between IGRP and BGP

When it comes to network routing there are two major protocols that many relate to IGRP (Interior Gateway Routing Protocol) and BGP (Border Gateway Protocol). These protocols are crucial in the guiding of data in networks but they are very different in their functions and work under different settings. It is therefore important for the network professional, who will implement the protocols in the design and management of efficient and reliable networks to understand the fundamental difference between IGRP and BGP. In this article we will learn about these two protocols and their uses, the pros and cons of applying these protocols in the network.

What is Interior Gateway Routing Protocol (IGRP)?

IGRP, in which uses distance vector protocol (interior) to exchange data within a system. IGRP uses composite metrics such as bandwidth, delay, load, and reliability, which are combined into a single metric to select the best route. IGRP uses IP protocol number 9 (it does not use TCP or UDP ports). Which is used for communication and by default every 90 seconds it updates the routing information.

Advantages of IGRP

Scalability: IGRP sustains large network with multiple subnets, it makes IGRP applicable for internal network complicated structure.
Metrics for Route Selection: IGRP uses bandwidth, delay, load, and reliability as composite metrics to select the best route.
Loop Prevention: split horizon, route poisoning and holddown timers are some of the mechanisms that IGRP brings into play meant at avoiding the development of routing loops, thus enhancing network stability.

Disadvantages of IGRP

Proprietary Protocol: IGRP is Cisco specialty, which is a proprietary interconnect protocol, which makes it incompatible with manufacturers’ equipment of other vendors.
Convergence Speed: IGRP is a distance-vector protocol and has slow convergence time than the present link-state protocol like OSPF, which leads to delayed in routing table updates.
Limited by Classful Routing: IGRP is a classful routing protocol and does not support VLSM, which can lead to inefficient IP address usage.

What is Border Gateway Protocol (BGP)?

In BGP, the Transmission control protocol is used. BGP is a path vector routing protocol used to exchange routing information between autonomous systems. It works by two independent networks (Autonomous Systems or AS) exchanging routing information. The two routers agree to exchange information about how to reach certain IP-ranges. BGP uses Transmission control protocol (TCP) port 179.

Advantages of BGP

Scalability: BGP is scalability in nature and it can work with the huge routing tables of the global internet environment and it can handle millions of routes.
Policy-Based Routing: BGP common characteristic is a richness of the filtering schemes reflection on the various attributes such as AS path, community tags, and prefix, which gives the administrators precise control over routing traffic.
Path Selection: The attributes like AS path length, next hop IP and route preference are used by the BGP to select the best path thus facilitating efficient path selection.
Support for VLSM: Another key feature is that the BGP also supports what is known as classless routing and hence better IP address usage.

Disadvantages of BGP

Complexity: BGP involves configuration and managing of routing policies as well as network topologies hence can be complicated.
Convergence Time: Although BGP is fully meshed. It can take long time to converge if there is a huge change in the routing domain, which affects the efficiency of the routing temporarily.
Security Risks: Currently, BGP is at risk of several threats which include route hijacking and BGP spoofing, which if executed can cause a major interference with internet traffic.