Routing In Fat Trees Protocol

Data Centers have been steadily growing to commonly host tens of thousands of end points, or more, in a single network. Because of their topologies (traditional and emerging), traffic patterns, need for fast restoration, and for low human intervention, data center networks have a unique set of requirements that is resulting in the design of routing solutions specific to them. Clos and Fat-Tree topologies have gained popularity in data center networks as a result of a trend towards centralized data center network architectures that may deliver computation and storage services.

The Routing in Fat Trees (RIFT) protocol addresses the demands of routing in Clos and Fat-Tree networks via a mixture of both link-state and distance-vector techniques colloquially described as 'link-state towards the spine and distance vector towards the leafs'. RIFT uses this hybrid approach to focus on networks with regular topologies with a high degree of connectivity, a defined directionality, and large scale.

The RIFT Working Group will work on a standards track specification of a specialized, dynamic routing protocol for Clos and fat-tree network topologies. The protocol will:
- deal with automatic construction of fat-tree topologies based on detection of links
- minimize the amount of routing state held at each topology level
- automatically prune topology distribution exchanges to a sufficient subset of links
- support automatic disaggregation of prefixes on link and node failures to prevent black-holing and suboptimal routing
- allow traffic steering and re-routing policies
- and provide mechanisms to synchronize a limited key-value data-store that can be used after protocol convergence

It is important that nodes participating in the protocol should need only very light configuration and should be able to join a network as leaf nodes simply by connecting to the network using default configuration.

The protocol must support IPv6 and should also support IPv4.

Working Group Details can be found here.