Towards PAR for Segment
Protection Switching
M Vinod Kumar
Abhay Karandikar
Agenda
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Refresh
Motivation
Gaps in Present Standard
Terminology for Segment Protection- agreed so
far
Summary of Segment Protection Requirements
Summary of Segment Protection Solutions
discussed so far in the group
Pros and Cons of various solutions
Need for a PAR
Prior Arts
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Eilat (May Interim) - Abhay presents SPS as means to solve P2MP protection
ay-Abhay-Protection-Switching-for-P2MP-0508.ppt
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Denver (July Plenary) – Jointly by Abhay, Bob and John
new-sultan-fast-reroute-te-0708-v02.pdf
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Seoul (Sept Interim) - Bob presents interpretations and observations, Dave presents
issues to address and Vinod presents case for SPS
new-sultan-segment-protection-scaling-0908-v01.pps
new-martin-PBB-TE-segment-prot-0908-v01.pdf
new-Protection-Vinod-Case-for-Segment-Protection-0908-v1.pps
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Dallas (Nov Plenary) -Vinod uploads document on case for SPS and No new work
prez due to Lack of time
new-Vinod-SegmentProtectionSwitching-1108-v01.doc
new-martin-PBB-TE-segment-prot-1108-v00.pdf
new-sultan-segment-protection-requirements-1108-v02.pdf
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New Orleans (Jan Interim) – Dave presents client-server method, Wei presents 3tupple translation, Bob presents segment protection for infrastructure, and Vinod
presents four distinct methods
new-martin-PBB-TE-segment-prot-0109-v00.pdf
new-weiyh-segment-protection-0109-v00.pdf
new-sultan-segment-protection-technical-proposal-0109-v01.pdf
new-vinod-SPS-modeling-0109-v1.ppt
Motivation
• Reference:
new-Protection-Vinod-Case-for-SegmentProtection-0908-v1.pps
• Carrier Requirements:
– Infrastructure failure- major cause of outage
– Service providers have the knowledge that
certain links are more prone to failure
• Upcoming areas/floods/road construction
– Protection models must include N:1
Gaps in Present Standard
• PBB-TE has addressed end-to-end
protection of P2P TESI within a single
domain.
• Service providers need efficient
mechanism to protect vulnerable links of
the topology
• N:1 is not addressed in PBB-TE.
Definitions of Segment
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A Segment is a single link, or a sequence of links and bridges, providing connectivity between two
bridges. The segment is bounded at each end by a Provider Network Port (PNP). A bridge lying
within the segment is a BCB. A segment endpoint bridge is a BCB or an IB-BEB.
A Primary segment is a segment along whose path one or more TESIs have been coincidently
provisioned
A Backup segment is a segment having the same endpoint bridges as the primary segment but
whose path is otherwise disjoint from the primary segment.
An Infrastructure Segment is Sequence of links and bridges that protects atleast one TESI
coincident with it
A Data Path Segment is portion of a TESI bounded by a PNP at each end
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Multiple Data Path segments can be associated with an infrastructure segment
Infrastructure Protection - Preserve connectivity of all TESIs transiting an active infrastructure
segment on the failure of one or more links or bridges associated with that segment.
Data Path Protection - Preserve connectivity of a TESI in the presence of a TESI data path
failure occurring within the active TESI segment due to link failure, node failure, FDB corruption,
etc.
M:1 Protection – Support multiple backup segments (M≥1) to which traffic can be switched in the
event of the failure of the primary segment. The backup segment having the highest provisioned
priority value among operational backup segments is selected to be the active segment. Should
support Load Balancing. M = 3 atleast.
Types of Segment Protection
Schemes
• Infrastructure Segment Protection
• Data Path Segment Protection
There is an agreement on the requirements
for Infrastructure Segment Protection
Infrastructure Segment Protection
Requirements
new-sultan-segment-protection-requirements-0109-v01.pdf
new-irene-Segment-Protection-Requirements-0309-v01.ppt
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Maintain the same or better quality of transport as offered by PBB-TE
End-to-end integrity must be honored
Solution must be operationally simple and should not require large number
of provisioning action
Solution shall not switch traffic when there is no fault unless required by
management commands
Shall have minimal impact on bridge architecture
Shall support N:1 protection group with load sharing support
Address the relatively high failure rate of particular links or bridges within a
network.
Address the likelihood of concurrent failures occurring in different segments
of a network.
Allow maintenance activities to be performed independently in different
segments of the network.
Provide an efficient means of protecting portions of a PtMP TESI.
Segment Protection Solutions
• Segment Protection Solutions can be
broadly classified in three types:
– Hierarchical (Client server by Dave, Triple Q
by Vinod Tejas)
– Cascaded (Tuple switch by Wei ZTE, BB-BEB
model by Vinod)
– Port redirection by Bob
• We consider Client-Server, Tuple
translation and port redirect.
Hierarchical Segment Protection
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This is also known as Client-Server model (Dave) or Triple MAC (Vinod)
Upgrade the BCBs at the edges of the segment to IB-BEBs and provide a PBB
hierarchal (802.1ah 26.6.1) S-tagged interface (802.1ah 25.4)􀂾
Each segment is now a new (server layer ) TESI in a regular PBB-TE 1:1 TESI PG,
with the corresponding TESI CCM integrity coverage
Cascaded Segment Protection
• Also known as 3-tupple translation (Wei
Yuehua) or Enhanced BB-BEB (Vinod)
Overlay Segment Protection
• Also known as port-redirect (Bob Sultan)
• Only addresses Infrastructure Segment Protection Switching
• Special logic needed at AIB and PIB to correlate the faults and portredirect or switch the TESI without forwarding ambiguity
Features
Hierarchical PBB-TE
3-Tupple Translation
Port-redirect
Data Frame size
Increase
Same
Same
Estimated Standards
Impact
None
Medium (TBD)
Low
Implications of EdgeSegment Protection
Back-2-back IBBEB
None
None
Protection Granularity
Group of TESIs
Per TESI
Group of TESI
Potential for Blind Switch
No
No
Yes
CCM complexity
Per Segment
Per TESI
Per Segment
Data Path Integrity
Yes
Yes
No
PAR
What do we get?
• Protection segments are pre-provisioned
to allow sub-50ms protection switching
• The segments forming protection group
are constantly monitored
• Optimal network resource utilization
– By protecting portion of e2e TESI
– By supporting load sharing with N:1
– By supporting minimal provisioning for
protection
Value Proposition
• Segment Protection has same economic feasibility as
that of Backbone Edge Bridges
• The protection mechanism is applicable to any topology
• Improves network utilization by not performing e2e
protection whenever possible
• Reduces provisioning complexity of e2e protection
mechanism by protecting portion of e2e transport
• Enables protection of critical portion of a packet transport
• Enables efficient protection of branches of P2MP
OAM requirements
• OAM shall reuse PBB-TE OAM
components
• No need to use unreliable control plane
What would IEEE specify
• Amendment to Qay
– Amend .1ag
Title
• IEEE standard for Local and Metropolitan
Area Networks --- Virtual Bridged Local
Area Networks --- Amendment ?? --Transport Segment Protection Switching
Scope: What project is
• The scope of this project is to define
feature extension of 802.1Q (2005)
supporting protection of critical portion of
the provisioned or traffic engineered
services by offering at-least the same
guarantee as offered originally by the
traffic engineered services with minimal
impact on existing standards
Scope: What Project is not
• The project will only provide features
necessary to support external
management plane command or control
plane.
• The selection of protection segment and
bandwidth management either through
management commands or by control
plane is outside the scope of this project
Scope: Required Features
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The features specified in this project enhance, support and rely on the PBB (IEEE
802.1ah), PBB-TE (IEEE 802.1Qay), and CFM (IEEE-802.1ag) standards. In doing
so, it shall:
– Maintain the same or better quality of transport as offered by PBB-TE
– End-to-end integrity must be honored
– Solution must be operationally simple and should not require large
number of provisioning action
– Solution shall not switch traffic when there is no fault unless required by
management commands
– Shall have minimal impact on bridge architecture
– Shall support N:1 protection group with load sharing support
– Address the relatively high failure rate of particular links or bridges
within a network.
– Address the likelihood of concurrent failures occurring in different
segments of a network.
– Allow maintenance activities to be performed independently in different
segments of the network.
– Provide an efficient means of protecting portions of a PtMP TESI.
Purpose
• An important objective of provisioned
packet transport is to efficiently protection
switch the traffic
– Use less network resources
– Sub-50 ms resiliency
– Build on existing standard building blocks
– Provide aggregate protection of all TESI
• This project will amend the .1Q standard
Need for Project
• Currently there is no mechanism to
manage portion of a (provisioned) packet
transport that is liable to fail more often
than other portion of the packet transport
• The project will address OAMP and
protection switching of critical portion of
the end-to-end packet transport and
support N:1 load sharing
Stakeholders
• Developers and users of networking for
Provider network environments including
networking IC developers, switch and NIC
vendors, and users.
Thank-you