Routing In Fat Trees

Document Charter Routing In Fat Trees WG (rift)
Title Routing In Fat Trees
Last updated 2018-02-09
State Approved
WG State Active
IESG Responsible AD Alvaro Retana
Charter Edit AD Alvaro Retana
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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.

The Working Group may establish additional requirements to constrain and inform
their work.

The RIFT Working Group is chartered for the following list of items:

 - A Standards Track specification that will include:
   - an Implementation Status section as described in RFC 7942
   - an Operational Considerations section to explain how the protocol is
   configured, deployed, and diagnosed, security and privacy mitigations for
   the protocol as identified in the threat analysis document. (q.v.)

 - A YANG module focused on configuration and monitoring of protocol instances

 - An Applicability Statement that describes how to deploy and configure the
 protocol in networks with different topologies

 - A Security Threat Analysis document that describes the attack vectors, which
 shall be sent for publication at the same time as the protocol