Interior Gateway Routing Protocol


The Interior Gateway Routing Protocol (IGRP) is a network routing protocol developed by Cisco Systems. It’s used by routers to exchange routing data within an autonomous system. IGRP is a distance-vector routing protocol, meaning it determines the best path for data packets based on distance and network speed.


The phonetics of “Interior Gateway Routing Protocol” are:Interior: In-tee-rih-orGateway: Gayt-wayRouting: Row-tingProtocol: Proh-tuh-kawl

Key Takeaways

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  1. Interior Gateway Routing Protocol (IGRP): IGRP is a proprietary protocol developed by Cisco. It is a distance-vector routing protocol used by routers to exchange routing data within an autonomous system.
  2. Metrics: IGRP utilizes a combination of factors or metrics to decide the best path for data transmission including bandwidth, delay, load, and reliability. It provides a more comprehensive and flexible approach to routing than protocols that use a single metric.
  3. Scalability and Stability: IGRP has the ability to scale for larger networks, supporting networks with up to 100 hops. It is also designed for a high degree of stability in changing network conditions, reducing unnecessary network traffic due to route changes.

“`I hope this summarizes the most important points about IGRP.


The Interior Gateway Routing Protocol (IGRP) holds significant importance in the field of Information Technology, particularly in networking, due to its advanced routing capabilities. IGRP, a proprietary protocol developed by Cisco Systems, allows routers in an autonomous system to exchange routing information, and this aids in maintaining the overall efficiency and accuracy of internetwork data transmission. Its noteworthy features like multiple metric attributes, load balancing, and the ability to avoid routing loops contribute to enhanced network stability and reliability. Moreover, its hierarchical network design allows for better scalability and control in large network environments. Thus, IGRP’s central role in supporting efficient, scalable, and reliable data transmission across networks underscores its technological importance.


The Interior Gateway Routing Protocol (IGRP) is a crucial aspect of networking and serves a fundamental purpose of helping to route data across large and complex networks, particularly those within an autonomous system, which refers to a network operated by a single enterprise or organization. IGRP performs its work through an algorithm for adjusting and designing the best possible path for data movement across a given network. This protocol, invented by Cisco Systems, is primarily used due to its optimization abilities and excellent ability to manage larger networks.The usage of IGRP avoids one of the most critical issues in networking — looping and route redundancies. By implementing a limit to the maximum looping in networking, IGRP assures a smooth data itinerary. Not only does it make the data transmission more efficient by choosing optimal paths based on factors like line delay, reliability, load, and bandwidth, but it also rebalances load dynamically across various routes. Hence, IGRP’s primary role is to maintain efficient and smooth digital communications within large and interrelated systems, ensuring optimal performance and consistent fluidity in data transmission.


1. Corporate Networks: Within a large corporation, IGRP could be used to manage the routing of data across a variety of internal networks. Sub-divisions or departments of the company may each have their own network, and IGRP will determine the fastest and most efficient route for data to travel among them. 2. University or College Campus: A university system could use IGRP to handle the routing within their campus network. With many buildings, facilities, departments, and research centers, the university network would require efficient management of data traffic. IGRP would help ensure that data is sent efficiently and accurately across the campus network.3. Internet Service Provider (ISP) Networks: ISPs could use IGRP for managing routing within their vast infrastructure network. Since ISP infrastructures are usually divided into several sub-networks (access, aggregation, core, etc.), this protocol can be used to decide the most effective path for data to pass from one network to another, ultimately ensuring better service for the consumers.

Frequently Asked Questions(FAQ)

**Q1: What is the Interior Gateway Routing Protocol (IGRP)?**A: The Interior Gateway Routing Protocol (IGRP) is a proprietary protocol used to exchange routing data within a computer network. It was developed by Cisco Systems.**Q2: How is IGRP different from other routing protocols?**A: IGRP takes several metrics into account such as bandwidth, reliability, delay and load, which makes it more flexible and robust compared to other routing protocols that only account for the path length.**Q3: What is the main objective of IGRP?**A: The main goal of IGRP is to offer a fast and efficient way to transfer information within a network and prevent loops that can lead to system failure.**Q4: Is IGRP still in use?**A: IGRP has largely been replaced by Enhanced Interior Gateway Routing Protocol (EIGRP) and Open Shortest Path First (OSPF) protocol. However, certain systems and networks may still use IGRP, especially those that haven’t been updated or replaced.**Q5: How does IGRP prevent routing loops?**A: IGRP mitigates routing loops by limiting the path that information travels to 100 hops. If the path exceeds this hop count, the data packet is considered to be unreachable.**Q6: What is the difference between IGRP and EIGRP?**A: EIGRP is an advancement of IGRP. It uses the same metrics as IGRP, but it also includes some additional factors like the interior gateway protocol and Autonomous System numbers. Moreover, EIGRP uses special algorithms for faster convergence.**Q7: Can IGRP and EIGRP interact with each other?**A: Yes, IGRP and EIGRP can interact through a process called redistribution, but this needs to be correctly configured to avoid common problems such as routing loops. **Q8: What networks support IGRP?**A: IGRP is a Cisco-proprietary protocol and is mainly supported in Cisco routers. However, with appropriate interoperability features, equipment from other manufacturers can also interact with IGRP networks. **Q9: How is the routing table created in IGRP?**A: IGRP uses the DUAL (Diffusing Update Algorithm) to create and update the routing table. Based on bandwidth, delay, reliability, and load, it determines the best route for data packets.**Q10: What is the maximum hop count in IGRP and why is it important?**A: The default maximum hop count in IGRP is 100, although it can be manually configured up to 255. This hop count is used to prevent routing loops and enables routers to determine the reachability of remote networks.

Related Tech Terms

  • Routing Information Protocol (RIP)
  • Open Shortest Path First (OSPF)
  • Enhanced Interior Gateway Routing Protocol (EIGRP)
  • Autonomous System
  • Distance Vector Algorithm

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