Source Demand Routing

Document Charter Source Demand Routing WG (sdr)
Title Source Demand Routing
Last updated 1998-03-23
State Approved
WG State Concluded
IESG Responsible AD (None)
Charter Edit AD (None)
Send notices to (None)


The SDR Working Group is chartered to specify and promote the use of 
(Source Demand Routing Protocol) as an inter-domain routing protocol
capability in conjunction with IDRP and BGP inter-domain routing
protocols.  The purpose of SDR is to support explicit selection of 
domain routes, to complement the implicit hop-hy-hop route selection
provided by BGP/IDRP.  The group is also chartered to specify and 
the use of a similar protocol for IPv6, referred to as the Explicit
Routing Protocol (ERP).

The goal of the SDR Working Group is to release the components of SDR as
``experimental'' IETF protocols and to obtain operational experience 
SDR in the Internet.  Once there is enough experience with SDR, the
working group will submit the SDR components to the IESG for

SDR has four components: packet formats for protocol control messages
and encapsulation of user datagrams, processing and forwarding of user
data and control messages, routing information distribution/collection
and route computation, configuration and usage.

The group's strategy is to:

(1) Define the format, processing and forwarding of user datagram and
control messages so that SDR can be used very early on as an efficient
means of supporting ``configured'' inter-domain routes.  User packets
are encapsulated along with the source route and forwarded along the
``configured'' route.  Routes are static at the inter-domain level, but
are not static in terms of the intra-domain paths that packets will
take between specified points in the SDR route. The impact of
encapsulation on MTU, ICMP, performance, etc., are among the issues that
must be evaluated before deployment.

(2) Develop simple schemes for collecting (a) dynamic domain-level
connectivity information and (b) route construction based on this
information, so that those domains that want to can make use of a
richer, and dynamic set of SDR routes.

(3) Apply the experience with SDR design and implementation to the
design and implementation of ERP.

(4) Develop SDR and ERP deployment plans.

(5) In parallel with (1), (2) and (3) , develop usage and configuration
documents and prototypes that demonstrate the utility of static-SDR and
simple-dynamic-SDR and ERP.

(6) After gaining some experience with the simple schemes for
distribution, develop a second generation of information distribution
and route construction schemes.  The group hopes to benefit from
discussions with IDPR and NIMROD developers at this future stage because
the issues faced are similar.  The route distribution and construction
mechanisms are common to both ERP and SDRP.

(7) Investigate the use of SDRP and ERP alternate routing as a mechanism
for supporting reservation traffic (e.g., based on RSVP).  This will
require that we address integration of SDRP/ERP and multicast routing
(e.g., running PIM over SDRP/ERP), as well as the interface between
SDRP/ERP and RSVP.  Moreover, we will investigate the construction of
SDRP/ERP routes that make use of some dynamic control information, in
additional to the more traditional hop count.

(8) The group will also investigate the addition of security options
into the SDRP/ERP forwarding and packet format specifications.

(9) Coordinate with the IDR and IPng Working Groups.