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  • Traditional Private Lease Line and Private Virtual Connection (PVC) are provided through T1/T3 or SONET/SHD access loops. They are complicated, costly, somewhat slow and not very scalable. They do offer very consistent and reliable performances, and have built-in OAM for fault detection and management.
  • Standards-based, end-to-end OAM is required for reasons such as: Automated configuration; fast service turn up End to end service control Hop-by-hop fault management Preventative maintenance and troubleshooting Customer notification of service degradation PM and SLA verification with CoS and QoS Network resilience and fast recovery Management and Control Plane to manage End-to-End OAM: Network Audit, NE Back-up, Restore etc. Configuration Management Fault of Troubleshooting Interface PM Collection Security Management with NE Access Control
  • Traditional Private Lease Line and Private Virtual Connection (PVC) are provided through T1/T3 or SONET/SHD access loops. They are complicated, costly, somewhat slow and not very scalable. They do offer very consistent and reliable performances, and have built-in OAM for fault detection and management.
  • Commence from the bottom up 802.3ah for local link monitoring 802.1ag for hierarchical service connectivity verification Y.1731 for end-to-end service performance monitoring Saying all that, all these standard have some duplicate capabilities in the fault and connectivity areas.
  • Mechanisms are: Discovery Remote Failure Indication - Dying gasp, link fault & critical event Remote Loopback Control – The ability to set remote port to loopback mode. This will loopback all control protocols inc. routing, OAM etc Performance monitoring and threshold crossing alarms Also intended for “Emulated” point-to-point links (e.g. OLT-ONT in PON case over a P-MP topology) are also included. But note that always 802.3 phy is required Slow Protocol (Max rate of 10 frames per second) Ethernet OAM shares BW with data payload OAMPDUs identified by MAC address and Ethernet Length/Type/subtype field Uses a protocol sub layer between physical and Data link layers All 802.3ah OAM PDUs must be untagged Extensibility: OAM is extensible through the use of the following: Organization Specific OAMPDU Organization Specific Information TLV Organization Specific Event TLV
  • CFM? Employs regular Ethernet frames that travel in-band with the customer traffic Devices that cannot interpret CFM Messages forward them as normal data frames
  • This example shows Maintenance Associations (MAs) between Maintenance End Points (MEPs) at three levels within a Maintenance Domain (MD). Maintenance Intermediate Points (MIPs) can be associated per MD or per MA which depends on the visibility the administer has configured.
  • Technically aligned with 802.1ag Uses slightly different terminology (Eg. MEG = MA in IEEE 802.1ag) 802.1ag specifies the FRAME FORMAT used by Y.1731 802.1ag and Y.1731 bodies worked closely together; hence, the standards provide extremely similar functionality Differences in recommendations exist as the work in IEEE was not completed when SG13 commenced its work on Y.1731 ETH-CC, ETH-LB, ETH-LT ETH-TEST Used to perform one-way on-demand in-service or out-of-service diagnostics tests. This includes verifying bandwidth throughput, frame loss, bit errors, etc.
  • SW_2009Carrier-Etherne...

    1. 1. Carrier Ethernet In-Depth: End-to-end OAM & Network-to-Network Interfaces Presenters Johannes Weingart Director, Application & Solution Management ADVA Optical Networking [email_address] Enrique Hernandez-Valencia Alcatel-Lucent [email_address]
    2. 2. Carrier Ethernet: End-to-End OAM A Key Element of the MEF’s Global Interconnect Strategy Johannes Weingart ADVA Optical Networking
    3. 3. Topics <ul><li>The challenge of End-to-End OAM </li></ul><ul><li>Solutions for fault detection and performance monitoring to support SLAs </li></ul><ul><li>Latest developments in the MEF </li></ul>
    4. 4. Challenges of CE for Service Providers <ul><li>Turn-up services quickly and efficiently </li></ul><ul><ul><li>Be competitive; get revenues ASAP </li></ul></ul><ul><li>Reliability/Up-time (99.999%) </li></ul><ul><ul><li>Enable SLAs and keep revenues </li></ul></ul><ul><li>Quality </li></ul><ul><ul><li>Enhance customer satisfaction and retention </li></ul></ul><ul><li>Efficient operation </li></ul><ul><ul><li>Reduce OPEX costs; be competitive and profitable </li></ul></ul><ul><li>On/Off-Net services </li></ul><ul><ul><li>Increase effective footprint </li></ul></ul><ul><ul><li>Access to national and global customer base </li></ul></ul>
    5. 5. OAM Drivers <ul><li>Carriers want visibility across other carriers’ networks, not into other carriers networks. </li></ul><ul><li>Standard based, End-to-End OAM </li></ul><ul><ul><li>Fault Detection, Verification & Isolation at every level </li></ul></ul><ul><ul><li>Customer notification of service degradation </li></ul></ul><ul><ul><li>PM and SLA verification with CoS </li></ul></ul><ul><li>Management Control Plane </li></ul><ul><ul><li>Configuration Management </li></ul></ul><ul><ul><li>PM Collections </li></ul></ul>
    6. 6. Response to Challenges – Advanced Tools <ul><li>Point-to-Point Link OAM (802.3ah) </li></ul><ul><li>End-to-End Service Connectivity Fault OAM (802.1ag) </li></ul><ul><li>End-to-End Service Performance Monitoring (Y.1731) </li></ul><ul><li>Two types of OAM– enhance automation </li></ul><ul><ul><li>Link OAM </li></ul></ul><ul><ul><ul><li>P2P Connectivity monitoring and troubleshooting </li></ul></ul></ul><ul><ul><li>Service OAM </li></ul></ul><ul><ul><ul><li>E2E Connectivity and Performance monitoring and troubleshooting </li></ul></ul></ul>
    7. 7. Outline <ul><li>The challenge of End-to-End OAM </li></ul><ul><li>Solutions for fault detection and performance monitoring to support SLAs </li></ul><ul><li>Latest developments in the MEF </li></ul>
    8. 8. OAM Layer Components <ul><li>Each layer supports OAM capabilities independently </li></ul><ul><li>OAMs interoperate </li></ul><ul><li>Component responsibilities are complementary </li></ul>E2E Performance Monitoring E2E Fault Monitoring “CFM” P2P Link Fault Management “EFM”
    9. 9. Architecture Building Blocks Point-to-Point EVC Carrier A E-NNI UNI Multi-point to Multi-point EVC UNI UNI Point-to-Point EVC UNI UNI UNI Link OAM 802.3ah E2E Service OAM: Fault-802.1ag Perform-Y.1731 Carrier B
    10. 10. Link OAM (IEEE 802.3ah, Clause 57) <ul><li>Provides mechanisms useful for ‘monitoring link operation’, such as: </li></ul><ul><ul><li>Discovery & Link Monitoring </li></ul></ul><ul><ul><li>Remote Failure Indication </li></ul></ul><ul><ul><li>Remote Loopback Control </li></ul></ul><ul><li>Sometimes referred to as Ethernet OAM or more commonly EFM (Ethernet First Mile) </li></ul><ul><li>Defines an optional OAM sub-layer: </li></ul><ul><ul><li>Intended for point-to-point IEEE 802.3 links </li></ul></ul><ul><ul><li>Uses “Slow Protocol” 1 frames called OAMPDUs which are never forwarded by MAC clients </li></ul></ul><ul><ul><li>Standardized: IEEE 802.3ah, clause 57 (now in 802.3-2005) </li></ul></ul>Data Link OSI Model Application Presentation Session Transport Network LLC OAM (Optional) MAC Physical
    11. 11. Service OAM - 802.1ag (aka “CFM”) <ul><li>What is IEEE 802.1ag? </li></ul><ul><ul><li>Provides for FAULT management of EVC-based service offerings. 802.1ag allows troubleshooting an end-to-end Ethernet Virtual Circuit (EVC) across multiple providers / vendors. </li></ul></ul><ul><li>What is “CFM”? </li></ul><ul><ul><li>CFM stands for “Connectivity Fault Management </li></ul></ul><ul><ul><li>Family of protocols that provides capabilities to detect, verify, isolate and report end-to-end Ethernet connectivity faults </li></ul></ul><ul><ul><li>CFM and 802.1ag are used interchangeably </li></ul></ul><ul><li>Standardized by IEEE (P802.1ag) in late 2007 </li></ul><ul><ul><li>IEEE std. 802.1ag-2007 </li></ul></ul><ul><ul><li>802.1ag is currently at revision 8.1 (CFM 8.1) </li></ul></ul>
    12. 12. Hierarchical OAM Domains <ul><li>A flat network is difficult to manage and define accountabilities </li></ul><ul><li>Hierarchical Maintenance Domains will bound OAM Flows & OAM responsibilities </li></ul>Network OAM Service OAM Customer Domain Provider Domain Operator Domain Operator Domain Customer Customer Service Provider UNI UNI E-NNI
    13. 13. End to End Service OAM: Maintenance Associations <ul><li>Maintenance Association (MA) – Boundaries of an Administrator’s scope of monitoring part of the network </li></ul><ul><li>Maintenance Domain (MD) – A level of monitoring within the hierarchy </li></ul><ul><li>Maintenance End Points (MEP) – End Points of the MA or MD </li></ul><ul><li>Maintenance Intermediate Points (MIP) – Intermediate Points within MA or MD </li></ul>
    14. 14. ITU-T Y.1731: Fault and Performance Management <ul><li>What is ITU-T Y.1731? </li></ul><ul><ul><li>A set of mechanisms for user-plane OAM functionality to provided fault and performance monitoring for point-to-point Ethernet networks. </li></ul></ul><ul><ul><li>Technically aligned with IEEE 802.1ag </li></ul></ul><ul><ul><li>Introduces performance measurements for SLA monitoring </li></ul></ul><ul><ul><ul><li>Delay Measurement (DM) </li></ul></ul></ul><ul><ul><ul><li>Delay Variation Measurement (DVM) </li></ul></ul></ul><ul><ul><ul><li>Loss Measurement (LM) </li></ul></ul></ul><ul><ul><li>Expands on fault notification and isolation </li></ul></ul><ul><ul><ul><li>Automatic Protection Switching (APS) </li></ul></ul></ul><ul><ul><ul><li>Ethernet Alarm Indication Signal function: ETH-AIS </li></ul></ul></ul><ul><ul><ul><li>Ethernet Test Signal function: ETH-TEST </li></ul></ul></ul>
    15. 15. OAM – Putting it all Together E-LMI E-LMI Service OAM; 802.1ag/Y.1731 <ul><li>End-to-End per EVC OAM </li></ul><ul><ul><li>Link Monitoring </li></ul></ul><ul><ul><li>Connectivity Fault Management </li></ul></ul><ul><li>Performance Monitoring and SLA metrics verification </li></ul><ul><li>MEF 16 E-LMI Service awareness; configuration and notification </li></ul>UNI UNI E-NNI 802.3ah 802.3ah 802.3ah 802.3ah 802.3ah 802.3ah 802.3ah 802.3ah 802.3ah
    16. 16. Outline <ul><li>The challenge of End-to-End OAM </li></ul><ul><li>Solutions for fault detection and performance monitoring to support SLAs </li></ul><ul><li>Latest developments in the MEF </li></ul>
    17. 17. MEF 20: UNI Type 2 Implementation Agreement <ul><li>Allows provider equipment to provision, configure and distribute EVC information and attributes to customer equipment. </li></ul><ul><li>Allows customer equipment to retrieve EVC status and configuration information from service provider equipment. </li></ul><ul><li>Adds new set of functionalities to the ones defined in UNI Type 1 </li></ul><ul><ul><li>Link OAM </li></ul></ul><ul><ul><li>E-LMI </li></ul></ul><ul><ul><li>Service OAM </li></ul></ul><ul><ul><li>Protection </li></ul></ul><ul><ul><li>Enhanced UNI Attributes </li></ul></ul><ul><ul><li>L2CP Handling </li></ul></ul>Private Customer Network End - user Ethernet Virtual Connection S S End - user Private Customer Network Subscriber Subscriber UNI UNI Metro Ethernet Network (MEN)
    18. 18. MEF 21: Abstract Test Suites for UNI Type 2 Part 1: Link OAM <ul><li>UNI Type 2 Certification Part 1 </li></ul><ul><ul><li>More complex to test than UNI Type 1 </li></ul></ul><ul><ul><li>Includes Ethernet link and service OAM </li></ul></ul><ul><ul><li>UNI Type 2 service requires backwards compatibility with UNI Type 1 </li></ul></ul><ul><ul><li>Components of UNI type 2 test suite such as Link OAM </li></ul></ul><ul><ul><li>Test one of the six elements of MEF 20 </li></ul></ul><ul><ul><li>Work on other areas is in progress </li></ul></ul><ul><ul><li>Comprehensive: 272 Test Cases </li></ul></ul><ul><ul><li>Approved July 2008 </li></ul></ul>
    19. 19. Service OAM: Performance and Fault Management <ul><li>Service OAM: Performance Management </li></ul><ul><ul><li>Purpose: service performance monitoring </li></ul></ul><ul><ul><li>Planned to consist of extensions to the Y.1731/IEEE 802.1ag procedures and protocols </li></ul></ul><ul><ul><li>Extensions are required to manage performance for multipoint EVCs since Y.1731 only covers Point-to-Point EVCs </li></ul></ul><ul><li>Fault Management </li></ul><ul><ul><li>Q.1731 and IEEE 802.1ag specify protocols and procedures for fault management of Ethernet services. </li></ul></ul><ul><ul><li>The goal of this Implementation Agreement is to specify how to use these two standards for the MEF standardized Ethernet services. </li></ul></ul>IMPORTANT NOTE This information is preliminary and is subject to change
    20. 20. Abstract Test Suites <ul><li>UNI Type 2 Testing Parts 2, 3 </li></ul><ul><ul><li>More complex to test than UNI Type 1 </li></ul></ul><ul><ul><li>Includes Ethernet service OAM </li></ul></ul><ul><ul><li>UNI Type 2 service requires backwards compatibility with UNI Type 1 </li></ul></ul><ul><ul><li>Components of UNI type 2 test suite such as Link OAM (completed as MEF 21) and E-LMI are work in progress </li></ul></ul><ul><li>E-NNI Testing </li></ul><ul><ul><li>Tests the function, protection & recovery mechanisms of two interoperating MENs via their External Network to Network Interfaces. Uses similar constructs used in MEF 9 & MEF 14 </li></ul></ul><ul><ul><li>Abstract Test Suite is work in progress, depends on completion of E-NNI base specification </li></ul></ul><ul><ul><li>Plans to include UNI services as far as they are mapped to E-NNI services </li></ul></ul><ul><li>Certification </li></ul><ul><ul><li>UNI Type 2 and E-NNI Certification are planned to be part of the MEF Certification Program </li></ul></ul>IMPORTANT NOTE This information is preliminary and is subject to change
    21. 21. Ethernet Standards Summary - <ul><li>G.8010 – Layer Architecture </li></ul><ul><li>G.8021 – Equipment model </li></ul><ul><li>G.8010v2 – Layer Architecture </li></ul><ul><li>G.8021v2 – Equipment model </li></ul><ul><li>Y.17ethmpls - ETH-MPLS Interwork </li></ul><ul><li>MEF 4 – Generic Architecture </li></ul><ul><li>MEF 2 – Protection Req & Framework </li></ul><ul><li>MEF 11 – UNI Req & Framework </li></ul><ul><li>MEF 12 – Layer Architecture </li></ul><ul><li>MEF 20 – UNI Type 2 </li></ul>- <ul><li>G.8011 – Services Framewrk </li></ul><ul><li>G.8011.1 – EPL Service </li></ul><ul><li>G.8011.2 – EVPL Service </li></ul><ul><li>G.asm – Service Mgmt Arch </li></ul><ul><li>G.smc – Service Mgmt Chnl </li></ul><ul><li>MEF 10.1 – Service Attributes </li></ul><ul><li>MEF 3 – Circuit Emulation </li></ul><ul><li>MEF 6.1 – Service Definition </li></ul><ul><li>MEF 8 – PDH Emulation </li></ul><ul><li>MEF 9 – Test Suites </li></ul><ul><li>MEF 14 – Test Suites </li></ul><ul><li>Services Phase 2 </li></ul>TMF ITU MEF <ul><li>TMF814 – EMS to NMS Model </li></ul><ul><li>Y.1730 – Ethernet OAM Req </li></ul><ul><li>Y.1731 – OAM Mechanisms </li></ul><ul><li>G.8031 – Protection </li></ul><ul><li>Y.17ethqos – QoS </li></ul><ul><li>Y.ethperf - Performance </li></ul><ul><li>MEF 7– EMS-NMS Info Model </li></ul><ul><li>MEF 15– NE Management Req </li></ul><ul><li>MEF 17 – Service OAM Requirements & Framework </li></ul><ul><li>Service OAM Protocol – Ph. 1 </li></ul><ul><li>Performance Monitoring </li></ul><ul><li>802.3ah – EFM OAM </li></ul><ul><li>802.1ag – CFM </li></ul><ul><li>802.1AB - Discovery </li></ul><ul><li>802.1ap – VLAN MIB </li></ul>Ethernet OAM <ul><li>802.3 – MAC </li></ul><ul><li>802.3ar – Congestion Management </li></ul><ul><li>802.1D/Q – Bridges/VLAN </li></ul><ul><li>802.17 - RPR </li></ul><ul><li>802.1ad – Provider Bridges </li></ul><ul><li>.1ah – Provider Backbone Bridges </li></ul><ul><li>.1ak – Multiple Registration Protocol </li></ul><ul><li>.1aj – Two Port MAC Relay </li></ul><ul><li>.1AE/af – MAC / Key Security </li></ul><ul><li>.1aq – Shortest Path Bridging </li></ul>Architecture/Control - Ethernet Services - <ul><li>G.8012 – UNI/NNI </li></ul><ul><li>G.8012v2 – UNI/NNI </li></ul><ul><li>MEF 13 - UNI Type 1 </li></ul><ul><li>MEF 16 – ELMI </li></ul><ul><li>E-NNI </li></ul><ul><li>802.3 – PHYs </li></ul><ul><li>802.3as - Frame Expansion </li></ul>Ethernet Interfaces Standards Body IEEE
    22. 22. Carrier Ethernet: External Network-to-Network Interfaces (E-NNI) A Key Element of the MEF’s Global Interconnect Strategy Enrique Hernandez-Valencia Alcatel-Lucent January 2009
    23. 23. Ethernet Service Demarcation Points <ul><li>UNI (User-to-Network Interface) </li></ul><ul><ul><li>Demarcation point between </li></ul></ul><ul><ul><ul><li>Ethernet Service Provider/Access Network Provider and Subscriber </li></ul></ul></ul><ul><ul><li>Ethernet Service (EVC) starting/ending point </li></ul></ul><ul><li>E-NNI (External Network-to-Network Interface) </li></ul><ul><ul><li>Demarcation/peering point between: </li></ul></ul><ul><ul><ul><li>Ethernet Service Provider (ESP) and Access Network Provider </li></ul></ul></ul><ul><ul><ul><li>ESP and Transport (Long Haul) Network Provider </li></ul></ul></ul>E-NNI Access Network Provider Transport Network Provider Ethernet Service Provider Subscriber Subscriber E-NNI E-NNI UNI UNI EVC
    24. 24. What is the MEF E-NNI? <ul><li>External Network to Network Interface (E-NNI) </li></ul><ul><li>A reference point where 2 Service Providers meet in support of specified MEF Services </li></ul><ul><li>Technical functionally supported by equipment at the specified reference point in support of MEF Services (*E-NNI Functional Element) </li></ul>UNI UNI UNI UNI UNI E-NNI UNI Reference Point EVC-1 Carrier A network Carrier B network
    25. 25. <ul><li>Service </li></ul><ul><ul><li>Type </li></ul></ul><ul><ul><li>MTU </li></ul></ul><ul><li>Endpoint </li></ul><ul><ul><li>Service Mux </li></ul></ul><ul><ul><li>Tag ID/CoS Preservation </li></ul></ul><ul><li>Link </li></ul><ul><ul><li>Rate </li></ul></ul><ul><ul><li>L2CPs </li></ul></ul>E-NNI Attributes Basic OAM Protection QoS <ul><li>Link OAM </li></ul><ul><ul><li>IEEE 802.3ah </li></ul></ul><ul><li>Service OAM </li></ul><ul><ul><li>IEEE 802.1ag & ITU-T Y.1731 </li></ul></ul><ul><li>Link Protection </li></ul><ul><ul><li>IEEE 802.3ad (LAG) </li></ul></ul><ul><li>Service Protection </li></ul><ul><ul><li>IEEE 802.1D (STP/MSTP) </li></ul></ul><ul><li>Bandwidth Profiles </li></ul><ul><ul><li>By EI </li></ul></ul><ul><ul><li>By EVC </li></ul></ul><ul><ul><li>By PCP </li></ul></ul><ul><ul><li>By DSCP </li></ul></ul><ul><li>Performance </li></ul><ul><ul><li>Delay </li></ul></ul><ul><ul><li>Loss </li></ul></ul><ul><ul><li>Availability </li></ul></ul>Similar attribute structure as current MEF specifications E-NNI Attributes
    26. 26. E-NNI Phase I <ul><li>In Scope: </li></ul><ul><li>E-LINE and E-LAN services (but not E-TREE) </li></ul><ul><ul><li>Inc. hair-pinning (e.g., frame may go in/out same PHY) </li></ul></ul><ul><li>Multiple Carrier Ethernet Networks </li></ul><ul><ul><li>Inc. multiple E-NNIs or links between two Carrier Ethernet Networks </li></ul></ul><ul><li>E-NNI link protection (but not End-to-End service protection) </li></ul><ul><ul><li>Customers & SP must provide loop-free connectivity </li></ul></ul><ul><li>End-to-End OAM and QoS </li></ul><ul><ul><li>Inc. traffic “coloring” via IEEE PCPs or IETF DSCPs </li></ul></ul><ul><li>Service Frame delineation via IEEE 802.1 </li></ul><ul><ul><li>No S-Tag or single S-Tag </li></ul></ul><ul><li>Approved MEF Specification </li></ul><ul><li>Available 2H 2009 </li></ul>
    27. 27. E-NNI Constructs: Component EVC (CEVC) <ul><li>MP-to-MP EVC 1 associates UNI 4 , UNI 5 and UNI 6 </li></ul><ul><li>EVC 1 decomposed into 3 CEVCs </li></ul><ul><ul><li>CEVC A1 within Operator A’s network </li></ul></ul><ul><ul><li>CEVC B1 within Operator B’s network </li></ul></ul><ul><ul><li>CEVC C1 within Operator C’s network </li></ul></ul>UNI 4 Operator A UNI 6 E-NNI Operator C E-NNI UNI 5 Operator B C1 A1 EVC 1 B1
    28. 28. Digging Tunnels <ul><li>Terminating Tunnel introduces the Termination End Points on a third party network </li></ul><ul><ul><li>Connects a Remote UNI on Network Operator to a Virtual UNI (V-UNI) from the Service Provider </li></ul></ul><ul><ul><li>The Terminating Tunnel passes all Subscriber traffic as is to </li></ul></ul><ul><li>Generalization of ESC* may introduce additional types of tunnels </li></ul>* ESC: Ethernet Services Constructs (Ongoing Project)
    29. 29. E-NNI Constructs: Tunnels, VUNIs and RUNIs <ul><li>Tunnels </li></ul><ul><ul><li>Terminating Tunnels (associates a VUNI and an RUNI) </li></ul></ul><ul><li>VUNI (Virtual UNI) </li></ul><ul><ul><li>Logical interface at endpoint of E-NNI side of Terminating Tunnel </li></ul></ul><ul><ul><li>Maps CEVC(s) to its Terminating Tunnel </li></ul></ul><ul><li>RUNI (Remote UNI) </li></ul><ul><ul><li>Logical interface at end point of UNI side of the Terminating Tunnel </li></ul></ul>UNI EVC 2 EVC 1 Operator 3 VUNI Terminating Tunnel E-NNI UNI Operator 2 RUNI EVC 1 EVC 2 EVC 3 E-NNI UNI UNI Operator 1
    30. 30. E-NNI Constructs: Putting it all together <ul><li>Access Network Provider </li></ul><ul><ul><li>Provides CEVC 1 connection between Subscriber UNI 1 (RUNI) and E-NNI 1 with Transport Network Provider </li></ul></ul><ul><li>Transport Network Provider </li></ul><ul><ul><li>Provides CEVC 2 connection between E-NNI 1 and E-NNI 2 with Ethernet Service Provider </li></ul></ul><ul><li>Ethernet Service Provider </li></ul><ul><ul><li>Provides connection to E-NNI 2 with Transport Network Provider </li></ul></ul><ul><ul><li>Provides End-to-End Ethernet Service to Subscriber </li></ul></ul><ul><ul><ul><li>Connects VUNI to Terminating Tunnel </li></ul></ul></ul><ul><ul><ul><li>Provides EVC between UNI 1 and UNI 2 </li></ul></ul></ul>E-NNI Transport Network Provider Ethernet Service Provider Access Network Provider RUNI E-NNI 1 and ENNI 2 Subscriber Subscriber VUNI UNI 2 UNI 1 Term.Tunnel Terminating Tunnel EVC E-NNI 1 E-NNI 2 CEVC 1 CEVC 2
    31. 31. For more information Visit: Thank You