Table of Contents

RIFT - Routing in Fat Trees

RIFT (Routing In Fat Trees) is a routing protocol that is designed for use in data center networks that use a fat tree topology. Fat tree is a network topology commonly used in modern data centers, which is characterized by its ability to provide a high degree of network bandwidth and low-latency communication between servers.

In a fat tree topology, the network is organized in a hierarchical structure with multiple layers of switches. At the top layer of the tree, there are one or more core switches that interconnect the lower layers of the tree. The middle layer of the tree is composed of aggregation switches, which interconnect multiple access switches at the bottom layer. Each access switch connects to multiple servers.

RIFT is designed to address the challenges of routing in fat tree networks, which include the need for efficient use of network bandwidth, low latency, and high network availability. RIFT achieves this by using a combination of centralized and distributed routing algorithms.

In RIFT, the core switches in the top layer of the tree are responsible for computing and distributing routing information to the other switches in the network. Each switch in the network maintains a routing table that specifies the best path to each destination.

RIFT also employs a technique called equal-cost multi-path (ECMP) routing, which allows multiple paths to be used for traffic between any two switches in the network. This helps to distribute traffic across the network and provides better network performance.

Overall, RIFT is a scalable and efficient routing protocol that is well-suited for use in modern data center networks that use a fat tree topology.


RIFT and BGP (Border Gateway Protocol) are both routing protocols used in data center networks, but they differ in their design goals and capabilities.

BGP is a widely used routing protocol that is commonly used in large-scale service provider networks and enterprise networks. It is designed for routing between different autonomous systems (AS) and exchanging routing information between different networks.

In contrast, RIFT is specifically designed for use in data center networks that use a fat tree topology. RIFT is optimized for high-bandwidth, low-latency communication within the data center network, and it can provide efficient and scalable routing in large data centers.

one of the important differences is that BGP is a more flexible protocol that can handle a wider range of routing scenarios, such as interconnecting different networks and providing transit services. In contrast, RIFT is designed specifically for fat tree topologies and may not be as suitable for other types of network topologies or routing scenarios.

In summary, while both RIFT and BGP are routing protocols used in data center networks, they have different design goals and capabilities. RIFT is optimized for high-bandwidth, low-latency communication within fat tree data center networks, while BGP is more flexible and suitable for a wider range of routing scenarios.

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Orhan Ergun, CCIE/CCDE Trainer, Author of Many Networking Books, Network Design Advisor, and Cisco Champion 2019/2020/2021

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