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Metro Ethernet Forum Layer 2 Services. Bob Klessig Member of the Board and Co-Chair of the Technical Committee Director of Engineering, Cisco Systems [email protected] Agenda. MEF Specifications Roadmap Services Model Traffic Management. MEF Services Technical Specifications.

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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 [email protected]


Agenda

Agenda

  • MEF Specifications Roadmap

  • Services Model

  • Traffic Management


Mef services technical specifications

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


Agenda1

Agenda

  • MEF Specifications Roadmap

  • Services Model

  • Traffic Management


Services model

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.


User network interface

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


Service frame

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


Service frame transparency

Service Frame Transparency

Service Frames must be delivered from ingress UNI to egress UNI(s) transparently except possibly as follows:

*Frame Check Sequence recalculated


Each service instance is a layer 2 vpn

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


Formal service instance definition

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


Point to point evc

Point-to-Point EVC

Exactly two UNIs are associated.


Multipoint to multipoint evc

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.


Identifying an evc at a uni

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.


Ce vlan id preservation

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


All to one bundling map

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


Using all to one bundling

Using All to One Bundling

Disaster RecoveryService Provider

Branch

HQ

Branch

Bridgeor Router

Private LineReplacement

LANExtension


One to one map

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


Ce vlan id translation

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


Using one to one map

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


Bundling map

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


Feature combinations and uses

Ethernet Line Service(E-Line)

Ethernet LAN Service(E-LAN)

Feature Combinations and Uses


Delivery of service frames

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


Handling layer 2 control protocols

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


Options for layer 2 control protocols

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


Agenda2

Agenda

  • Specifications Roadmap

  • Services Model

  • Traffic Management


Caveat

Caveat

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


Two areas covered by traffic management

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


Bandwidth profile overview

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


Bandwidth profile defined by token bucket algorithm

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


Two options for algorithm

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


Bandwidth profile parameters

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.


Detailed algorithm extension of rfc 2697

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.


Three ways to apply bandwidth profile to a service frame

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


Bandwidth profile policing

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


Two ways to identify cos instance

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


Class of service

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


Ethernet for man kind www metroethernetforum org

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


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