Which of the following is an advanced distance vector routing protocol that automates routing tables and also uses some features of link-state routing protocols?
A. OSPF
B. RIP
C. EIGRP
D. BGP
The Correct Answer and Explanation is:
The correct answer is C. EIGRP (Enhanced Interior Gateway Routing Protocol).
EIGRP is an advanced distance vector routing protocol developed by Cisco. While it is primarily categorized as a distance vector protocol, it incorporates features of link-state protocols, making it a hybrid protocol. EIGRP automates the creation and updating of routing tables, allowing routers to exchange information about the best routes for traffic within an autonomous system (AS).
Here’s why EIGRP fits the criteria outlined in the question:
1. Distance Vector Features:
EIGRP operates as a distance vector protocol in the sense that routers share information about the routes they know, specifically the best path to a destination network. Routers using EIGRP exchange this information only with their directly connected neighbors, similar to traditional distance vector protocols like RIP (Routing Information Protocol). However, unlike RIP, EIGRP only sends updates when there are changes in the network, reducing bandwidth usage and processing overhead.
2. Link-State-like Features:
EIGRP borrows key concepts from link-state protocols such as OSPF (Open Shortest Path First). For example, it uses the Diffusing Update Algorithm (DUAL) to ensure loop-free and efficient route calculation. DUAL allows EIGRP to quickly determine the shortest path to a destination network and provide rapid convergence if there are changes in the network topology. This makes EIGRP more efficient and scalable compared to purely distance vector protocols like RIP.
3. Automated Routing Tables:
One of the significant features of EIGRP is its ability to automate routing table updates, ensuring that routers in the network maintain up-to-date information about the best possible routes. EIGRP tracks various metrics such as bandwidth, delay, load, and reliability to compute the best path, compared to simpler protocols like RIP that rely only on hop count.
In summary, EIGRP is considered a hybrid routing protocol because it combines the best of both distance vector and link-state protocols, offering efficiency, fast convergence, and scalability in large networks.