EIGRP, or Enhanced Interior Gateway Routing Protocol, is a dynamic routing protocol that was developed by Cisco in the early 1990s. It is based on the Distance Vector algorithm, but with some enhancements that make it more efficient, scalable, and reliable than its predecessors. In this article, we will explore how EIGRP has evolved over time, from its original version to its current standard.
The original version of EIGRP, also known as EIGRP Classic, was proprietary to Cisco and only supported IPv4 networks. It used a complex metric that combined bandwidth, delay, reliability, and load to determine the best path to a destination. It also used a Diffusing Update Algorithm (DUAL) to maintain a loop-free topology and avoid counting to infinity. EIGRP Classic had several features that made it superior to other routing protocols at the time, such as fast convergence, partial and incremental updates, multiple equal-cost paths, and support for various network types.
EIGRP was really the choice if you ran an all Cisco network back in the olden times. Stuck In Active routes where a challenge once your network reached a certain side. This is where good IPAM practices can actually help your network. Ultimately the end solution for many SIA routes is the use stub routing with EIGRP of course! The real benefit was the ability to filter EIGRP routes. The more backup links you have the messier things get for path redundancy. Things can get very messy by the acquisition of one company and another, you will most likely need to filter routes until a network redesign is completed.
EIGRP (Enhanced Interior Gateway Routing Protocol) has evolved significantly since its introduction. Initially proprietary to Cisco, it became an open standard in 2013. Over time, Cisco introduced enhancements to improve scalability, stability, and convergence times. The introduction of named EIGRP made configuration more straightforward and added support for IPv6, addressing the growing need for advanced networking protocols. With the advent of EIGRPv6, it further solidified its place in modern networking, facilitating the transition to IPv6.
In 2013, Cisco introduced a new version of EIGRP, called EIGRP Named Mode, that aimed to simplify the configuration and management of the protocol. EIGRP Named Mode allowed administrators to create a single configuration block for each EIGRP instance, instead of using multiple commands for different aspects of the protocol. EIGRP Named Mode also introduced some new features, such as support for IPv6 networks, wide metrics that can handle higher bandwidth links, and stub routers that can limit the amount of routing information exchanged with other routers.
In 2016, Cisco decided to make EIGRP an open standard and submitted a draft to the Internet Engineering Task Force (IETF). The draft defined the basic functionality and operation of EIGRP, as well as the packet formats and message types. The draft also specified how EIGRP can interoperate with other routing protocols, such as OSPF and BGP. The draft did not include some of the Cisco-specific features, such as named mode, wide metrics, or stub routers. The draft was intended to encourage other vendors and developers to implement EIGRP on their platforms and devices.
EIGRP is a popular choice for network administrators due to its ease of configuration and troubleshooting, as it only requires a single command to enable the protocol and automatically discovers and forms neighbor relationships with other routers. Additionally, EIGRP offers fast and reliable convergence in case of network changes or failures, while maintaining multiple backup paths to a destination. It is also scalable and flexible, able to support large and heterogeneous networks with different topologies and link speeds. Furthermore, EIGRP is secure and efficient, utilizing authentication and encryption to protect routing information while only sending updates when necessary.
EIGRP is quick and easy to setup as a LAN routing protocol should be. Tweaked with a few routing options, EIGRP was the stalwart of many networks located within Canada. Some of these networks spanned coast to coast, while others may have only been retail sites together. EIGRP was used by many critical infrastructures because of the scalability and reliability. One of the major selling points was that you could run multiple instances to create "Bridge Routers". Put that along with the ability to filter routes and tag routes for complex routing environments it made it the choice de jour.
Network administrators need to be aware of the challenges associated with EIGRP, such as its lack of support from other vendors, granularity, transparency, and adaptability. EIGRP is mainly a Cisco protocol and has compatibility issues with other routing protocols. Additionally, it does not allow for different routing policies or preferences based on criteria such as source, destination, or application. Furthermore, it does not provide much visibility into the internal workings of the protocol or the state of the network. Lastly, it does not support advanced features such as traffic engineering, load balancing, or multipath routing.
Some key aspects of EIGRP's evolution include: 1. Improved convergence time: EIGRP has been optimized to reduce convergence time, making it quicker to adapt to network changes and failures. 2. Enhanced security features: EIGRP now includes additional security features, such as authentication mechanisms, to protect against unauthorized access and attacks. 3. Scalability improvements: EIGRP has been enhanced to support larger networks and accommodate the growing number of devices and routes. 4. Integration with other routing protocols: EIGRP has been designed to work alongside other routing protocols, such as OSPF and BGP, to provide more flexibility and options for network administrators.