What are the features and limitations of using EIGRP as a dynamic routing protocol?

1 EIGRP basics

EIGRP is a Cisco proprietary protocol that uses a hybrid approach of distance vector and link state algorithms. It supports multiple network layer protocols, such as IPv4, IPv6, IPX, and AppleTalk. It also supports classless interdomain routing (CIDR), variable length subnet masking (VLSM), and route summarization. EIGRP uses a metric based on bandwidth, delay, reliability, load, and MTU to select the best path to a destination. It exchanges routing information with its neighbors using hello packets and update packets.

2 EIGRP features

One of the main features of EIGRP is its fast convergence, which means it can quickly adapt to changes in the network topology and restore connectivity. EIGRP achieves this by maintaining a topology table that contains all the possible routes to a destination, and a feasible successor table that contains the backup routes. EIGRP also uses a diffusing update algorithm (DUAL) that prevents routing loops and ensures loop-free paths. Another feature of EIGRP is its scalability, which means it can handle large and complex networks with minimal bandwidth and CPU overhead. EIGRP uses partial and incremental updates that only send the changed information, and split horizon and route poisoning techniques that prevent unnecessary updates.

3 EIGRP limitations

Despite its features, EIGRP also has some limitations that you should be aware of. One of the limitations is its lack of interoperability, which means it can only work with other Cisco devices or devices that support EIGRP. This can limit your network design and vendor choices, and increase your costs. Another limitation is its complexity, which means it can be challenging to troubleshoot and optimize, especially in large networks with multiple areas and autonomous systems. EIGRP also requires careful planning and configuration of parameters such as bandwidth, delay, variance, and K values, to ensure optimal performance and stability.

4 EIGRP alternatives

If you are looking for alternatives to EIGRP, you might consider some of the other dynamic routing protocols that are available. For example, you could use OSPF, or Open Shortest Path First, which is an open standard protocol that uses a link state algorithm and supports hierarchical network design and load balancing. OSPF also has faster convergence and better security than EIGRP. However, OSPF also has some drawbacks, such as higher memory and CPU consumption, more complex configuration and administration, and potential flooding of link state advertisements. Another option is RIP, or Routing Information Protocol, which is a simple and widely supported protocol that uses a distance vector algorithm and hop count as the metric. RIP is easy to configure and troubleshoot, but it has slow convergence, limited scalability, and prone to routing loops.

5 EIGRP best practices

If you decide to use EIGRP as your dynamic routing protocol, you should follow some best practices to ensure optimal performance and reliability. This includes using consistent network addressing and subnetting schemes, passive interfaces or distribute lists, route summarization and filtering, authentication and encryption, as well as network monitoring and debugging tools. These measures will help limit EIGRP traffic to the necessary interfaces, reduce the size and complexity of the routing table, secure communication from unauthorized access or modification, and verify your configuration and operation for any issues or errors.

6 EIGRP summary

EIGRP is a dynamic routing protocol that offers fast convergence, scalability, and flexibility for your network. However, it also has some limitations, such as lack of interoperability, complexity, and configuration sensitivity. Therefore, you should weigh the pros and cons of EIGRP before choosing it as your routing protocol, and compare it to other options such as OSPF or RIP. You should also follow some best practices to ensure your EIGRP network runs smoothly and securely.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?