802.1Qay PBB-TE Protection Switching Overview

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802.1Qay PBB-TE Protection Switching Overview
Joint ITU-T/IEEE Workshop on The Future of
Ethernet Transport (Geneva, 28 May 2010)

• Panagiotis Saltsidis
• Ericsson

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What is PBB-TE?
Provisioned Control
Customer Network
Customer Network

• Provider Backbone Bridges Traffic Engineering
  is the latest development in a series of ongoing
  efforts to enable support for advanced
  connectivity service offerings by a network of
  Bridges.
• It corresponds to a set of functions that enable
  support for full traffic engineering of paths in
  a bridged network.
• PBB-TE disables the MSTP control plane for a
  subset of VLANs, using instead either the
  management plane or another (possibly external)
  control plane to populate filtering database
  table entries of related bridges

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Services in a Bridged Network

• The main design principle is based on a building
  blocks model where the added functionality is
  mainly confined at the external interfaces
  associated with a specific service demand.
• The same network is able to offer PBB-TE services
  (Traffic Engineered Service Instances TESIs),
  Provider Backbone Bridged services (B-VLANs) and
  Provider Bridged services (S-VLANs).

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UNI
4
Geneva, 28 May 2010
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IEEE802.1Qay Summary

• Enables construction of point-to-point and
  point-to-multipoint traffic engineered paths
  (TESIs) by splitting of the VID space between
  distributed spanning tree protocols and
  provisioned control.
• Supports discard of frames with unknown
  destination addresses and disables learning for
  B-VIDs under provisioned control.
• Supports the operation of Continuity Check,
  Loopback, and Linktrace protocols on
  point-to-point and point-to-multipoint TESIs.
• Supports 11 protection switching capable of load
  sharing for point-to-point TESIs.
• Provides required extension to SNMP management by
  SMIv2 MIB modules

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TESI Definitions

• Ethernet Switched Path (ESP) A provisioned
  traffic engineered unidirectional connectivity
  path among two or more Customer Backbone Ports
  (CBPs) that extends over a PBBN. An Ethernet
  Switched Path is point-to-point or
  point-to-multipoint.
• point-to-point TE service instance A TE service
  instance supported by two point-to-point ESPs
  where the ESPs endpoints have the same Customer
  Backbone Port (CBP) MAC addresses.
• point-to-multipoint TE service instance A TE
  service instance supported by a set of ESPs that
  comprises one point-to-multipoint ESP from the
  root to n leaves plus a point-to-point ESP from
  each of the leaves to the root.

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802.1Qay - Protection

• PBB-TE provides end-to-end linear protection for
  point-to-point TESIs, where a dedicated
  protection point-to-point TESI is established for
  one particular working point-to-point TESI, and
  the traffic is automatically switched from the
  working TESI to the protection TESI when a
  failure occurs on the working entity.
• Failure is detected by the operation of the
  Continuity Check protocol
• Switching is achieved by changing the Backbone
  Service Instance table B-VID entries on the
  Customer Backbone Ports associated with the TESI
  MEPs.

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IEEE802.1Qay PS State Machines

• The local protection commands and protection
  behavior specified by IEEE802.Qay follow the
  architectural model used in ITU-T Recommendation
  G.8031.
• The priorities associated with the various
  requests in IEEE802.1Qay are in general alignment
  with the corresponding priorities in ITU-T G.8031
  and the corresponding state machine operation in
  IEEE802.Qay is in alignment to the state
  transition tables in G.8031. The only differences
  in the state machine operation are related to the
  inclusion of the MStoWorking request which is
  referred by protection switching documents in
  ITU-T (e.g., G870) but has been dropped by G.8031
  and that the precedence of p.SF and FS are
  inverted since G.8031 relies on an APS protocol
  to be running on the protection path.

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G.8031/IEEE802.1Qaydifferences

• The protected entity is different.
• G.8031 protection applies to point-to-point VLAN
  based Ethernet Subnetwork Connections.
• IEEE802.1Qay protection applies to a
  point-to-point TESI in a traffic engineered
  region.
• The protection scope is different.
• G.8031 supports linear 11 and linear 11
  protection switching architectures.
• IEEE802.1Qay is required to support 11 path
  protection capable of load sharing.
• G.8031 specifies an in-band Automatic Protection
  Switching (APS) protocol, whereas signaling in
  IEEE802.1Qay is provided by CCM flags.
• There are a few specific differences regarding
  the externally observable protection switching
  behavior. In particular, in IEEE802.1Qay
• The Hold-off function is applied to all SF
  indications,
• A Manual Switch request is supported to switch
  traffic to the working entity,
• A Force Switch has precedence over an SF-P,
• The receiver combines traffic from both the
  working and protected entities,
• An SF results from any of the following defects
  xconCCMdefect, errorCCMdefect, someRMEPCCMdefect,
  someRDIdefect.

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TE Protection Groupsand load sharing

• The protection switching mechanism is capable of
  load sharing as the TE service instances that are
  assigned to a TE protection group can be re-used
  in a number of TE protection groups enabling a
  list of I-SIDs to be distributed among a set of
  interdependent TE protection groups.
• A set of interdependent TE protection groups
  forms a coordinated protection group.
• Protection switching requests to interdependent
  TE protection groups must be coordinated for an
  operator to manage the TESIs in a coherent manner
  and to avoid potentially competing requests for
  each TESI.

Protection Group Working TESI Protection TESI Coordinated PGs
PG_A TESI_1 TESI_2 PG_A, PG_C
PG_B TESI_3 TESI_4
PG_C TESI_2 TESI_1 PG_A, PG_C
Backbone Service Instance Protection Group
I-SID_1 PG_A
I-SID_2 No PG
I-SID_3 PG_C
I-SID_4 PG_B
I-SID_5 PG_B
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Traffic Field in the CCM flags

• TESI MEPs make use of the Traffic Field in the
  CCM Flags Field in order to identify traffic
  misalignments on point-to-point TESIs

RDI
Traffic Field
CCM Interval

• The bit is set whenever the BSI instance table
  associated to the TESI MEP has an I-SID entry for
  the monitored TESI

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Mismatch Defects

• Mismatch Defects are detected whenever
• Differences in the Traffic fields of transmitted
  and received CCMs
• simultaneous settings of the RDI and Traffic
  fields
• are reported for a specified period of time

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802.1Qay PS operation summary

• IEEE802.1Qay follows the architectural model used
  in ITU-T Recommendation G.8031 and the state
  machine operation is similar to the state
  transition tables in G.8031.
• The main differences are due to the different
  requirements associated with PBB-TE
• TESIs are provided in a network domain that is
  under the overall control of an external agent
  with high levels of management/control
  requirements
• The PBB-TE PS operation is capable of load
  sharing