The ability for a node to specify a forwarding path, other than the normal shortest path, that a particular packet will traverse, benefits a number of network functions, for example: o Some types of network virtualization, including multi- topology networks and the partitioning of network resources for VPNs o Network path and node protection such as fast re-route o Network programmability o New OAM techniques o Simplification and reduction of network signalling components o Load balancing and traffic engineering Source-based routing mechanisms have previously been specified for network protocols, but have not seen widespread adoption other than in MPLS traffic engineering. These applications may require greater flexibility and per packet source imposed routing than can be achieved through the use of the previously defined methods. The SPRING working group will define procedures that will allow a node to steer a packet along an explicit route using information attached to the packet and without the need for per-flow state information to be held at transit nodes. Full explicit control (through loose or strict path specification) is gained through a network comprising only SPRING nodes, however SPRING must inter-operate through loose routing in existing networks and may find it advantageous to use loose routing for for other network applications. There is an assumed trust model such that any node imposing an explicit route on a packet is assumed to be allowed to do so, however administrative and trust boundaries may strip explicit routes from a packet. Initial work will focus on SPRING within in a single AS, however design decisions must not preclude operation of SPRING across AS boundaries. SPRING should support both centralised and distributed path computation. SPRING should both provide support for its use as an OAM tool in SPRING enabled networks, and the necessary OAM and other management tools needed to manage a SPRING enabled network. SPRING should avoid modification to existing data planes that would make them incompatible with existing deployments. Where possible, existing control and management plane protocols must be used within existing architectures to implement the SPRING function. Any modification of or extension to existing architectures, data planes, or control or management plane protocols must be carried out in the working groups responsible for the architecture, data plane, or control or management plane protocol being modified and in co-ordination with this working group, but may be done in this working group after agreement with all the relevant WG chairs and responsible Area Directors. The SPRING working group is chartered for the following list of items: o Identification and evaluation of use cases for SPRING. These use cases must include a definition of the data plane for the environment in which they are to be deployed. o Definition of requirements and/or any new data plane encodings and procedures, required to implement the use cases. Such procedures must include the necessary security considerations. o Definition of requirements and/or any new control plane mechanism needed to enable the use cases. o Definition of requirements and/or management plane mechanism needed to manage and operate a SPRING enabled network. The SPRING working group will not work on any mechanisms for use in networks that forward IPv4 packets. The working group will develop the following documents: o One or more documents describing SPRING use cases. o Specification of a high-level abstract architecture for SPRING and requirements for modifications to existing architectures to support SPRING. o Specification of any required new procedures to support SPRING use cases. o One or more data plane extension requirements documents, including documenting the impact on existing deployments of the existing data plane. o One or more control protocol extensions requirements documents. o Document inter-working and co-existence between the new procedures and the existing signalling and routing protocols. o Inter-operability reports pertaining to the implementation of extensions supporting SPRING.