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Metro Ethernet Forum Layer 2 Services

Metro Ethernet Forum Layer 2 Services. Bob Klessig Member of the Board and Co-Chair of the Technical Committee Director of Engineering, Cisco Systems bklessig@cisco.com. Agenda. MEF Specifications Roadmap Services Model Traffic Management. MEF Services Technical Specifications.

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Metro Ethernet Forum Layer 2 Services

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  1. Metro Ethernet Forum Layer 2 Services Bob Klessig Member of the Board and Co-Chair of the Technical Committee Director of Engineering, Cisco Systemsbklessig@cisco.com

  2. Agenda • MEF Specifications Roadmap • Services Model • Traffic Management

  3. MEF Services Technical Specifications MEF 1.0Ethernet Services Model, Phase1* Technical descriptions of service features MEF x.0Traffic Management Specification, Phase1 Fractional Bandwidth and Performance MEF x.0Ethernet Services Definitions, Phase1 Specific service instances *http://www.metroethernetforum.org/PDFs/Standards/MEF-1.0.doc

  4. Agenda • MEF Specifications Roadmap • Services Model • Traffic Management

  5. Services Model CustomerEdge (e.g., router) (CE) CustomerEdge (CE) MetroEthernetNetwork ServiceAttributes A service is what the CE sees. The technology used inside the MEN is not visible.

  6. User Network Interface The demarcation point between Service Provider and Subscriber Responsibilities CE CE MetroEthernetNetwork • Dedicated to a single Subscriber • Based on Standard Ethernet PHYs for Phase 1, e.g., • RJ45 Socket on Service Provider owned Ethernet switch • RJ45 plug on Service Provider owned cable UNI UNI

  7. Service Frame • The Layer 2 protocol data unit exchanged between the CE and the MEN at the UNI • Standard Ethernet • With IEEE 802.1Q tag (up to 1522 bytes) • Without IEEE 802.1Q tag (up to 1518 bytes) • Includes everything but the preamble • More than 100 Million devices exist that are potential Customer Edge devices

  8. Service Frame Transparency Service Frames must be delivered from ingress UNI to egress UNI(s) transparently except possibly as follows: *Frame Check Sequence recalculated

  9. Each Service Instance is a Layer 2 VPN Example showing a green serviceand a blue service. ServiceMultiplexed UNI • Service Frames cannot leak in or out of a Service Instance • Multiple Service instances can exist at a UNI, called Service Multiplexing

  10. Formal Service Instance Definition Ethernet Virtual Connection (EVC) • Association of two or more UNIs • Service Frames can only be exchanged among the associated UNIs • A Service Frame sent into the MEN via a particular UNI MUST NOT be delivered out of the MEN via that UNI

  11. Point-to-Point EVC Exactly two UNIs are associated.

  12. Multipoint-to-Multipoint EVC • Two* or more UNIs are associated • A broadcast or multicast ingress frame is typically replicated and delivered to all of the other UNIs * A MP2MP EVC with two UNIs is different than a P2P EVC since additional UNIs can be added at any time.

  13. Identifying an EVC at a UNI CE-VLAN ID/EVC Map Service Frame Format Untagged*Priority Tagged*Tagged, VID = 1Tagged, VID = 2...Tagged, VID = 4094Tagged, VID = 4095 CE-VLAN ID 12...40944095 EVC RedGreen...Blue CE-VLAN ID/EVC Map *Untagged and Priority Tagged Service Frames have the same CE-VLAN ID and that value is configurable at each UNI. This is the behavior expected by an IEEE 802.1Q CE.

  14. CE-VLAN ID Preservation CE-VLAN ID37 EVCBlue EVCBlue CE-VLAN ID37 • CE-VLAN ID/EVC Map for EVC must be identical at all UNIs in the EVC and • Priority Tagged in must be priority tagged out • Untagged in must be untagged out

  15. All to One Bundling (Map) Untagged*Priority Tagged*Tagged, VID = 1Tagged, VID = 2...Tagged, VID = 4094Tagged, VID = 4095 CE-VLAN ID12...40944095 EVCRed CE-VLAN ID/EVC Map • Only one EVC at the UNI (no service multiplexing) • All CE-VLAN IDs map to this EVC – no need for coordination of CE-VLAN ID/EVC Map between Subscriber and Service Provider • EVC must have CE-VLAN ID Preservation

  16. Using All to One Bundling Disaster RecoveryService Provider Branch HQ Branch Bridgeor Router Private LineReplacement LANExtension

  17. One to One Map UntaggedPriority TaggedTagged, VID = 1Tagged, VID = 2...Tagged, VID = 4094Tagged, VID = 4095 CE-VLAN ID12...40944095 EVCRedBlue CE-VLAN ID/EVC Map • No more than one CE-VLAN ID is mapped to each EVC at the UNI • If CE-VLAN ID not mapped to EVC, ingress Service Frames with that CE-VLAN ID are discarded • Service Multiplexing possible • CE-VLAN ID Preservation not required • Subscriber and Service Provider must coordinate CE-VLAN ID/EVC Map

  18. CE-VLAN ID Translation CE-VLAN ID37 EVCBlue EVCBlue CE-VLAN ID156 • CE-VLAN ID/EVC Map can be different at different UNIs in an EVC • Fine for CE routers • Problematic for CE bridges

  19. Using One to One Map InternetService Provider CE-VLAN ID Preservationwould constrain ISP 178  Blue179  Yellow180  Green 2000  Green ISPCustomer 3 2000  Blue 2000  Yellow ISPCustomer 1 ISPCustomer 2 Frame Relay PVCReplacement Router

  20. Bundling (Map) Untagged*Priority Tagged*Tagged, VID = 1Tagged, VID = 2...Tagged, VID = 4094Tagged, VID = 4095 CE-VLAN ID123..40944095 EVCRedBlue CE-VLAN ID/EVC Map • More than one CE-VLAN ID is mapped to an EVC at the UNI • Service Multiplexing possible • CE-VLAN ID Preservation is required for EVC if multiple CE-VLAN IDs mapped to it • Subscriber and Service Provider must coordinate CE-VLAN ID/EVC Map

  21. Ethernet Line Service(E-Line) Ethernet LAN Service(E-LAN) Feature Combinations and Uses

  22. Delivery of Service Frames • Broadcast • Deliver to all UNIs in the EVC but the ingress UNI • Multicast • Typically delivered to all UNIs in the EVC but the ingress UNI • Unicast • Typically delivered to all UNIs in the EVC but the ingress UNI if not learned • Otherwise, deliver to the UNI learned for the destination MAC address • Learning is important for Multipoint-to-Multipoint EVCs • Type of Service Frame determined from the destination MAC address

  23. Handling Layer 2 Control Protocols Need to worry about Layer 2 Control Protocols Bridge BridgingExample Bridge Bridge • Bridges will try to run Spanning Tree Protocol by exchanging Bridge Protocol Data Units (BPDUs) • If BPDUs are blocked, loop will result and Ethernet Service will be unusable • Solutions: Use routers or deliver Subscriber BPDUs

  24. Options for Layer 2 Control Protocols • Discard • PDU from CE discarded by MEN • PDU never egresses from MEN • Peer • MEN peers with CE to run protocol • Tunnel • PDUs carried across MEN as if they were normal data • EVC is that associated with the CE-VLAN ID of the PDU, e.g., the Untagged CE-VLAN ID for most standard Layer 2 Control Protocols defined by IEEE 802

  25. Agenda • Specifications Roadmap • Services Model • Traffic Management

  26. Caveat MEF Traffic Management work is still evolving and likely to change significantly.

  27. Two Areas Covered by Traffic Management • Bandwidth Profile • How to buy just the bandwidth you need and have a predictable bill • Class of Service • Identifying the CoS for a Service Frame • Performance parameters that define a CoS

  28. Bandwidth Profile Overview • Similar in concept to the traffic policing of Frame Relay • Bandwidth Profile is a characterization of the lengths and arrival times of Service Frames at the UNI • The level of compliance with the Bandwidth Profile is assessed for each ingress Service Frame • Green = full compliance • Yellow = partial compliance • Red = non-compliance • Delivery performance then based on compliance level

  29. Bandwidth Profile Defined by Token Bucket Algorithm CommittedInformationRate ExcessInformationRate “Green”Tokens “Yellow”Tokens Overflow Overflow CommittedBurst Size ExcessBurst Size C-Bucket E-Bucket If (Service Frame length less than C-Bucket tokens) declare green and remove tokens from C-Bucket else if (Service Frame length less than E-Bucket tokens) declare yellow and remove tokens from E-Bucket else declare red

  30. Two Options for Algorithm Option 1: Decoupled Option 2: Coupled “Green”Tokens “Green”Tokens Overflow Overflow C-Bucket C-Bucket “Yellow”Tokens “Yellow”Tokens Overflow Overflow E-Bucket E-Bucket

  31. Bandwidth Profile Parameters • Committed Information Rate (CIR) expressed as bits per second. CIR  0. • Committed Burst Size (CBS) expressed as bytes. CBS  0. • Excess Information Rate (EIR) expressed as bits per second. EIR  0 • Excess Burst Size (EBS) expressed as bytes. EBS  0. • Coupling Flag (S). S = 0 or 1.

  32. Detailed Algorithm (Extension of RFC 2697)* Frame of length lj arrives at tj Bc(tj) = min{CBS, Bc(tj-1) + CIR(tj – tj-1)} Be(tj) = min{EBS, Be(tj-1) + EIR(tj – tj-1) + Smax[0, Bc(tj-1) + CIR(tj – tj-1) – CBS]} Yes Declare frame greenBc(tj) = Bc(tj) - lj lj≤ Bc(tj) No Yes Declare frame yellowBe(tj) = Be(tj) - lj lj≤ Be(tj) No Declare frame red *Algorithm for “color blind” mode. A “color aware” version exists but requires some way to identify the color of the ingress Service Frame.

  33. Three Ways to Apply Bandwidth Profile to a Service Frame • Per ingress UNI • Per EVC at the ingress UNI • Per CoS instance at the ingress UNI (see below for CoS identification) • Multiple methods can apply at a UNI but configuration must be such that only one Bandwidth Profile is applied to each ingress Service Frame

  34. Bandwidth Profile Policing • Green • Deliver Service Frame with performance levels as per the Service Level Agreement for the CoS instance • Yellow • Deliver Service Frame but Service Level Agreement for the CoS instance does not apply • Red • Discard

  35. Two Ways to Identify CoS Instance • EVC • All Service Frames mapped to the same EVC receive the same CoS • <EVC,set of user_priority values> • All Service Frames mapped to an EVC with one of a set of user_priority values receive the same CoS

  36. Class of Service • A Class of Service is defined by three performance objectives • Frame Delay: P percentile of delay ≤ d msec • Frame Jitter: Definition TBD • Frame Loss: Percent of frames lost ≤ p% • Phase 1 will cover only Point-to-Point EVCs

  37. “Ethernet for MAN-kind”www.MetroEthernetForum.org

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