Preliminary draft of PAR Scope, Purpose, Reason, and 5 Criteria for Shortest Path Bridging - for comment - revision 0.2

As agreed at the closing 802.1 plenary in Atlanta, the upcoming interim meeting is empowered to draft a PAR for Shortest Path Bridging for circulation to other working groups and possible approval at the July 802 plenary  meeting. The following is a preliminary draft to get the discussion on the PAR started.

The most important part of all this is the Scope,  as the scope words need to appear verbatim (or very close) in the final amendment.

Title of Document: Draft:

Standard for Local and Metropolitan Area Networks: Virtual Bridged Local Area Networks – Amendment 7?: Shortest Path Bridging

Scope of Proposed Project:

This standard specifies shortest path bridging of unicast and multicast frames, including protocols to calculate multiple active topologies that can share learnt station location information, and support of a VLAN by multiple, per topology, VLAN identifiers (VIDs).

Purpose of Proposed Project:

This amendment will augment the existing, successful, multi-vendor interoperable bridging specifications to allow use of shortest path communication within administratively defined network regions, while retaining concurrent support for all existing capabilities and configurations.

Reason for the Proposed Project:

At present traffic for each VLAN (Virtual Local Area Network) is confined to a single spanning tree of bridges and LANs. By removing this restriction, this amendment will increase the bandwidth that can be supported by bridged subnetworks, improve network utilization, and minimize latency.

5 Criteria

1. Broad Market Potential

A standards project authorized by IEEE 802 shall have a broad market potential. Specifically, it shall have the potential for:

a) Broad sets of applicability.

Shortest path bridging is applicable wherever the size of each bridged region in the network is currently limited by lack of the bandwidth efficiency due to the restricted communications paths available to individual VLANs, rather than by other considerations. The coexistence of this technology with existing VLAN deployments and configurations means that these will not have to be 'traded off' to realize its benefits. A significant part of the installed base of VLAN bridges is believed to be capable of taking advantage of shortest path bridging as a software upgrade, easing and speeding deployment.

b) Multiple vendors and numerous users.

The multiple bridge vendors that are represented in the IEEE 802.1 WG have all expressed strong interest in shortest path bridging. There has been continued strong interest in the user community in technologies that offer best path capability and relieve the current restriction of each VLAN to a single spanning tree.

c) Balanced costs.

Shortest path bridging capability is not expected to materially increase the cost of individual VLAN bridges, while lowering the overall cost of newly designed large bridged networks through improved link utilization. In some new designs the number of IP routers necessary in the network may be reduced. The overall effect of this technology will be to lower network costs.

2. Compatibility

IEEE 802 defines a family of standards. All standards shall be in conformance with the IEEE 802.1 Architecture, Management and Internetworking documents as follows: 802. Overview and Architecture, 802.1D, 802.1Q and parts of 802.1f. If any variances in conformance emerge, they shall be thoroughly disclosed and reviewed with 802.

Each standard in the IEEE 802 family of standards shall include a definition of managed objects which are compatible with systems management standards.

This amendment will not change the conformance of IEEE Std 802.1Q to Std 802. Overview and Architecture, or its relationship to that specification.

Equipment conforming to the proposed amendment to IEEE Std 802.1Q will be compatible and interoperable with bridge implementations that conform to IEEE Std 802.1D and prior revisions of IEEE Std 802.1Q, and support of existing network configurations will be retained in parallel with use of the additional capabilities provided by this amendment. No change to end stations will be required to take advantage of these capabilities.

This amendment will include extensions to MIBs, existing or under development as part of other 802.1 projects, to allow management of shortest path bridging as a natural extension of existing capabilities.

3. Distinct Identity

Each IEEE 802 standard shall have a distinct identity. To achieve this, each authorized project shall be:

a) Substantially different from other IEEE 802 standards

IEEE Std 802.1Q is the sole and authoritative specification for VLANs and VLAN-aware Bridges

b) One unique solution per problem (not two solutions to a problem).

The proposed amendment will extend existing VLAN technology and has not been anticipated by any other specification, in IEEE 802 or elsewhere.

c) Easy for the document reader to select the relevant specification.

IEEE Std 802.1Q is the natural reference for VLAN bridging technology, which will make the capabilities added by this amendment easy to locate.

4. Technical Feasibility

 For a project to be authorized, it shall be able to show its technical feasibility. At a minimum, the proposed project shall show:

 a) Demonstrated system feasibility.

The proposed amendment is based on known 802.1Q VLAN technology.

b) Proven technology, reasonable testing.

The proposed amendment is based on known 802.1Q VLAN technology.

c) Confidence in reliability.

The reliability of this solution is anticipated to be the same as that of others based on existing 802.1Q VLAN technology.

d) Coexistence of 802 wireless standards specifying devices for unlicensed operation.

Not applicable.

5. Economic Feasibility

 For a project to be authorized, it shall be able to show economic feasibility (so far as can reasonably be estimated), for its intended applications. At a minimum, the proposed project shall show:

 a) Known cost factors, reliable data.

The proposed technology is no expected to materially alter individual VLAN Bridge equipment costs, while lowering the overall costs of new network designs (see also Broad Market Potential). The Connectivity Fault Management technology being developed as P802.1ag will continue to be supported by shortest path bridging, thus containing operational costs.

b) Reasonable cost for performance.

The proposed technology will provide additional network performance without the addition of equipment.

c) Consideration of installation costs.

Installation costs of VLAN Bridges are not expected to be significantly affected, any increase in network design costs is expected to be more than offset by a reduction in the number of separate bridged subnetworks required.