ECMP for 802.1Qxx
Proposal for PAR and 5 Criteria
Version 2
16 people from ECMP ad-hoc committee
Project Authorization Request
Title
• PAR for an amendment to existing Standard 802.1Q-2011
• P802.1Qxx
• IEEE Standard for Local and Metropolitan Area Networks--Virtual Bridged Local Area Networks :
Amendment:
Equal Cost Multiple Paths (ECMP)
Scope
• This standard specifies protocols, procedures and managed objects
to support utilizing multiple possible next hop choices for frames
within a single service in SPBM networks.
• This is accomplished by applying one of a set of standard functions
per frame at ingress and using the result as an input to all subsequent
choices among multiple next hops as the frame transits the SPBM
network. These functions are selected to ensure that frames
belonging to the same data flow take the same path.
• It is anticipated that a new Tag will be defined possibly including a
Time to Live (TTL) field.
• The standard will ensure that Connectivity Fault Management (CFM)
can be used to proactively monitor and diagnose the paths that data
takes through the network.
Dependencies
• This standard is dependent on the
completion of 802.1aq.
Purpose
• .1Qxx provides the additional capability to use many more equal cost
paths than 802.1aq’s current ECT mechanism due to improved
scaling properties with respect to network diameter.
• .1Qxx would be used in conjunction with an 802.1aq based control
plane and would use specific B-VIDs and new ECT-ALGORITHMs as
defined by 802.1aq.
• .1Qxx may include multipath function information and may use TTL
loop mitigation. Corresponding new EtherTypes would identify the
new Tag formats.
• It is expected that both the current 802.1aq ECT and 802.1Qxx
ECMP would be used at the same time in the same network (for
different traffic/service categories) but differentiated by B-VID.
• 802.1Qxx enhances Connectivity Fault Management (CFM) to
monitor and diagnose the richer connectivity of .1Qxx.
Need
• As diameter and number of adjacencies grow the number
of paths increases exponentially. In such richly connected
networks ECMP in addition to ECT allows for better
utilization in proportion to the state required.
• TTL augments loop mitigation in the face of hardware,
software and design failures.
• An augmented SPBM with this capability addresses
urgent customer requests to meet the above needs with a
single protocol, a single data path and a unified OA&M
suite.
Stakeholders
• Vendors, users, administrators, designers, customers,
and owners of Provider Backbone Bridged Networks,
Carrier Ethernet Networks or next generation data
centers.
Other Standards with a Similar
Scope
• There are no IEEE standards solving this
problem.
• There are other standards (TRILL, VPLS)
that cover parts of the problem
encompassed by 802.1Qxx but the scope
of this standard is more complete than any
of them.
Other Questions
• no
Five Criteria
Broad Market Potential
– Broad sets of applicability.
• The commercial provision of Ethernet services across a Data Center,
metropolitan or larger networks is large and growing business. Provider
Backbone Networks are a significant part of this market and a required
component of the evolving Data Center. 802.1Qxx enables even
greater use of these richer topologies.
– Multiple vendors and numerous users.
• This work is being proposed by a number of major vendors
representing the majority of current users in the market.
– Balanced costs (LAN versus attached stations).
• This project does not materially alter the existing cost structure of
bridged networks. Attached stations would not be aware of the
operations by transit bridges.
Compatibility
– IEEE 802 defines a family of standards. All standards shall be in
conformance with the IEEE 802.1 Architecture, Management and Interworking 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.
• 802.1Qxx would use the 802.1aq SBPM ECT-Algorithm framework for
forwarding compatibility. This guarantees that 802.1Qxx bridges can be added
to a network of 802.1aq bridges to increment the network functionality.
– Each standard in the IEEE 802 family of standards shall include a definition
of managed objects that are compatible with systems management
standards.
• Such a definition will be included.
.
Distinct Identity
– Substantially different from other IEEE 802 standards.
• This is an amendment to 802.1Q the only standard for VLAN aware
bridges.
– One unique solution per problem (not two solutions to a problem).
• There is currently no general on-data-path solution for ECMP
forwarded frames.
– Easy for the document reader to select the relevant specification.
• This project will amend only the IEEE 802 standard defining VLAN
aware bridges.
Technical Feasibility
– Demonstrated system feasibility.
• Hash based ECMP is widely deployed in IP networks and is well understood.
The main issue is one of OA&M and we will standardize Ethernet solutions
to OA&M issues raised by this new behavior.
– Proven technology, reasonable testing.
• The main concepts are well proven. No unproven test technologies are
required.
– Confidence in reliability.
• ECMP has wide spread use today with known acceptable reliability.
– Coexistence of 802 wireless standards specifying devices for
unlicensed operation.
• Not applicable
Economic Feasibility
– Known cost factors, reliable data.
• Minimally this will require either a software upgrade to NPU based
Ethernet switches, or in the case of ASIC based devices a new BVID behavior that mirrors existing 802.1ah with the exception of a
hash based choice of possible next hops. There would therefore be
a cost upgrade for ASIC based switches.
– Reasonable cost for performance.
• The required hardware and software changes are a fraction of the
cost of a typical network and provide commensurate additional
capabilities.
– Consideration of installation costs.
• This functionality can be incrementally introduced thus minimizing
installation costs.