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

Agenda MEF Specifications Roadmap Services Model Traffic Management

Services Model Customer Edge (e.g., router) (CE) Customer Edge (CE) Metro Ethernet Network Service Attributes A service is what the CE sees. The technology used inside the MEN is not visible.

User Network Interface The demarcation point between Service Provider and Subscriber Responsibilities CE CE Metro Ethernet Network 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 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 Frames must be delivered from ingress UNI to egress UNI(s) transparently except possibly as follows: Ingress Service Frame Egress Service Frame* Untagged Tagged Tagged w/ different value *Frame Check Sequence recalculated

Each Service Instance is a Layer 2 VPN Example showing a green service and a blue service. Service Multiplexed 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 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

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

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 CE-VLAN ID/EVC Map Service Frame Format Untagged* Priority Tagged* Tagged, VID = 1 Tagged, VID = 2 . . . Tagged, VID = 4094 Tagged, VID = 4095 CE-VLAN ID 1 2 . . . 4094 4095 EVC Red Green . . . 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 EVC Blue EVC Blue CE-VLAN ID 37 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) Untagged* Priority Tagged* Tagged, VID = 1 Tagged, VID = 2 . . . Tagged, VID = 4094 Tagged, VID = 4095 CE-VLAN ID 1 2 . . . 4094 4095 EVC Red 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 Disaster Recovery Service Provider Branch HQ Branch Bridge or Router Private Line Replacement LAN Extension

One to One Map Untagged Priority Tagged Tagged, VID = 1 Tagged, VID = 2 . . . Tagged, VID = 4094 Tagged, VID = 4095 CE-VLAN ID 1 2 . . . 4094 4095 EVC Red Blue 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 EVC Blue EVC Blue CE-VLAN ID 156 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 Internet Service Provider CE-VLAN ID Preservation would constrain ISP 178  Blue 179  Yellow 180  Green 2000  Green ISP Customer 3 2000  Blue 2000  Yellow ISP Customer 1 ISP Customer 2 Frame Relay PVC Replacement Router

Bundling (Map) Untagged* Priority Tagged* Tagged, VID = 1 Tagged, VID = 2 . . . Tagged, VID = 4094 Tagged, VID = 4095 CE-VLAN ID 1 2 3 . . 4094 4095 EVC Red Blue 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 CE-VLAN ID/EVC Map Characteristic EVC Type Point-to-Point Multipoint-to-Multipoint All to One Bundling Private Line replacement with Router or Bridge LAN Extension with Router or Bridge One to One Map Frame Relay replacement with Router Uses TBD Bundling Ethernet Line Service (E-Line) Ethernet LAN Service (E-LAN)

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 Need to worry about Layer 2 Control Protocols Bridge Bridging Example 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 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

Agenda Specifications Roadmap Services Model Traffic Management

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

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 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 Committed Information Rate Excess Information Rate “Green” Tokens “Yellow” Tokens Overflow Overflow Committed Burst Size Excess Burst 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 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 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)* 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 green Bc(tj) = Bc(tj) - lj lj ≤ Bc(tj) No Yes Declare frame yellow Be(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 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 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 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 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

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