ethernet oam overview: making ethernet manageable · link oam (ieee 802.3, clause 57) ethernet uni...

© 2008 Cisco Systems, Inc. All rights reserved. 1

Ethernet OAM Overview:Making Ethernet Manageable

Dr. Frank Brockners

DFN-Forum, Mai 2008

© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 2

Drivers for Ethernet OAM

OAM benchmarksSet by TDM and existing WAN technologies

Operational EfficiencyReduce OPEX, avoid truck-rolls

Downtime cost

Management ComplexityLarge Span Networks

Multiple constituent networks belong to disparate organizations/companies


Ethernet OAMProtocol positioning

Access AccessCoreCustomer Customer

ProviderBridges

BackboneBridges

ProviderBridges

BackboneBridges

IP/MPLS

Business

Residential

Business

Residential

UNI UNINNINNINNI

EthernetLink OAM

E-LMIConnectivity

Fault Management

E-LMI: User to Network Interface (UNI)Link OAM: Any point-point 802.3 linkCFM: End-to-End Ethernet virtual connection


Different Service Domains……Result in Different OAM Domains

The Domain-Onion: Visibility of each domain is limited to its border elements with its peering domains and its own internal elements

U-PE C

N-PE 3

N-PE 4N-PE 2

N-PE 1

CustomerEquipment

SP Network

PW

Access Core

U-PE D

MPLS

MPLSSONET/SDH

NativeEthernet

CE

CE CE

CEU-PE A

U-PE B

Operator 1Operator 1 Operator 2Operator 2

Operator 3Operator 3


Service ProviderService Provider

CustomerCustomer


OAM and Layering

The only common element between Source and Sink is the transport of a Layer-2 Ethernet frame

The whole Layer-2 world (all Layer-2 devices) needs to support E-OAM

Proper layering allows you to put together a network using very different Layer 1 media

Layer 2 world ( ) consists of end-stations, e.g. hosts, routers, bridges connected by a layer-1 media (or layer-1 media emulation)

Layer 3 tunnel (e.g. EoMPLS) or EoS is an Emulated Layer 1 (pseudowire) in this environment

Native Ethernet(over dark fiber)

EoMPLS EoSONET/SDH Native Ethernet(over dark fiber)

“Layer 1”

Layer 2Ethernet

Bridge Bridge Bridge Router Router Router Router XC Router Bridge

Incorrect –Violates Layering


Ethernet Physical OAM & LMI


U-PE C

N-PE 3

N-PE 4N-PE 2

N-PE 1

CustomerEquipment

SP Network

PW

Access Core

U-PE D

MPLS

MPLSSONET/SDH

NativeEthernet

CE

CE CE

CEU-PE A

U-PE B

Link OAM (IEEE 802.3, Clause 57)

Ethernet UNI

Link OAMLink OAM

Maintain consistency of an Ethernet transport connection (per link, or “physical” OAM)

Address three key operational issues when deploying Ethernet across geographically disparate locations

Operates on a single point-to-point link between 2 devices

Slow protocol using packets called OAMPDUs which are never forwarded

Standardized: IEEE 802.3, clause 57


802.3 Clause 57 OAM—Key Functions

Link monitoringbasic error definitions for Ethernet so entities can detect failed and degraded connections

Fault signalingmechanisms for one entity to signal another that it has detectedan error

Remote loopbackused to troubleshoot networks, allows one station to put the other station into a state whereby all inbound traffic is immediately reflected back onto the link

OAM DiscoveryDiscover OAM support and capabilities per device


U-PE C

N-PE 3

N-PE 4N-PE 2

N-PE 1

CustomerEquipment

SP Network

PW

Access Core

U-PE D

MPLS

MPLSSONET/SDH

NativeEthernet

CE

CE CE

CEU-PE A

U-PE B

Ethernet LMI

Ethernet UNI

E-LMIE-LMI

Enables service providers to reduce customer configuration errors, as well as improve EVC performance by shaping on CE egress

Eases deployment for service providers

Reduces the policing configurations required on Metro Ethernet gear

LMI is complementary to OAM


U-PE C

N-PE 3

N-PE 4N-PE 2

N-PE 1

CustomerEquipment

SP Network

PW

Access Core

U-PE D

MPLS

MPLSSONET/SDH

NativeEthernet

CE

CE CE

CEU-PE A

U-PE B

Ethernet LMI

Ethernet UNI

E-LMIE-LMI

An LMI may be used to signal various parameters regarding a service to a customer device from a PE deviceTypes of Information

EVC StatusProvisioning & Configuration Data

Technical approach based on Frame Relay LMIPart of MEF UNI Type 2 (beyond standard Ethernet)Specification Completed:http://www.metroethernetforum.org/PDFs/Standards/MEF16.doc


EEE P802.1ag Connectivity Fault ManagementITU Y.1730, Y.1731MEF 9

Service OAM and Assurance


OAM Functions and Mechanisms for Ethernet NetworksConnectivity Fault Management

IEEE 802.1D;P802.1aq;P802.1Qay; G.8031

MST/STP; SPB; PBB-TE; Ethernet Protection Switching

Fault Recovery

Y.1731MEF 9

ETH-TestEquipment Test SuiteTest

MEF ProjectY.1731Multiple ParametersPerformance

Y.1731Alarm Indication Signal (ETH-AIS)

Fault Notification/ Alarm Indication

P802.1ag CFMY.1731

Path Trace and LoopbackFault Isolation

P802.1ag CFMY.1731LoopbackFault Verification

P802.1ag CFMY.1731Continuity CheckFault Detection and

Fault Notification


ComparingIEEE 802.3 (Clause 57) OAM and IEEE 802.1ag CFM

802.1ag Connectivity Fault Management Provides Service Level OAM, and Therefore Is Typically Higher Priority than 802.3 OAM

IEEE P802.1ag (Published December 17, 2007), ITU SG 13/3Standard Approved by IEEE 802

Joint Effort by IEEE 802.1, ITU-TCreated by One Committee (IEEE 802.3)

Multiple Instances Operating at Multiple Levels SimultaneouslySingle Instantiation per Wire

Connectivity Verification, Traceroute, Ping, Alarm Indication/Suppression

Discovery, Statistics Enquiry, Keepalive, Loopback (Mirror) Mode

May Be Per-Service or Per-Wire; Passes End-to-End through Bridges

Operates on Physical Link Only, Cannot Pass through a Bridge

IEEE 802.1ag Connectivity Fault Management

IEEE 802.3 Clause 57 Link OAM


Ethernet OAM Supports the Domain Concept

Maintenance DomainsDefined by Operational/Contractual Boundaries

Customer/Service Provider/Operator

MD may nest and touch, but never intersect

Up eight levels of “nesting”: MD-Level (0..7)

Maintenance AssociationsMonitor connectivity of a particular service instance in a given MD

Identified by MAID (“Domain name”—multiple forms possible, including DNS)

U-PE C

N-PE 3

N-PE 4N-PE 2

N-PE 1

CustomerEquipment

SP Network

PW

Access Core

U-PE D

MPLS

MPLSSONET/SDH

NativeEthernet

CE

CE CE

CEU-PE A

U-PE B

Operator 1Operator 1 Operator 2Operator 2


Operator 4Operator 4Service ProviderService Provider

CustomerCustomer


P802.1ag CFM ConceptsMaintenance Association Points

Maintenance Association Point (MP) is function an interface (port) participating in CFM

Defined per MA-Level and VLAN

Maintenance Association End Points (MEPs, 13-Bit MEP-ID): At the edge of a MA/Domain; Active: Source/Rcv CFM messages

Maintenance Association Intermediate Points (MIPs): Internal to a MA/Domain; Passive: Recv and Respond to certain CFM messages

CustomerEquipment

CustomerEquipment

Operator ABridges

Operator BBridges

MEP MEPMIP MIP

MEP MEPMIPMIP

MEP MEP MEP MEPMIP MIP MIPMIPMIPMIP

MIPMIP

CustomerLevel

ProviderLevel

OperatorLevel


P802.1ag CFM ConceptsCFM Messages

CFM uses standard Ethernet Frames

CFM frames are distinguishable byEther-Type (and MAC Address for multicast messages): 0x8902

CFM frames are sourced, terminated, processed and relayed by Bridges

Bridges that cannot interpret CFM Messages must forward them as normal data frames; routers can support limited CFM functionality

All CFM Messages are confined per Maintenance Domain and per VLAN

Three types of Messages:Continuity Check Message (CCM)

Loopback Message (LBM), Loopback Reply (LBR)

Link Trace Message (LTM), Link Trace Reply (LTR)

556677

Four address bits “y”MD Level of CCM

1100

223344

01-80-C2-00-00-3y

556677

Four address bits “y”MD Level of CCM

1100

223344

01-80-C2-00-00-3y

Continuity Check Message (CCM)Group Destination MAC Addresses

D5E6F7

Four address bits “y”MD Level of LTM

9180

A2B3C4

01-80-C2-00-00-3y

D5E6F7

Four address bits “y”MD Level of LTM

9180

A2B3C4

01-80-C2-00-00-3y

Linktrace Message (LTM)Group Destination MAC Addresses


P802.1ag CFM ConceptsContinuity Check (CCM; ITU: ETH-CC)

MEP MEPMIPMIPCatalogue Catalogue Catalogue and Terminate

11 22 33

CustomerEquipment

CustomerEquipment

Operator ABridges

Operator BBridges

Per-Domain, per-VLAN Multicast “heart-beat” messages.Carries status of port on which MEP is configured

Uni-directional (no response)

Transmitted at a configurable periodic interval by MEPs (3 1/3ms–10min)

Catalogued by MIPs at the same MA-Level, terminated by remote MEPs at the same MA-Level


CCM – Parameters & Performance

Source: IEEE 802.1ag, D8.1


P802.1ag CFM ConceptsLoopback (LBM, LBR; ITU: ETH-LB)

Source DestinationCustomerEquipment

CustomerEquipment

Operator ABridges

Operator BBridges

MEP MEPMIPMIP

1. Loopback Request2. Loopback Reply

11

22

11

22

ping Ethernet mac-address {domain domain-name | level level-id} vlan vlan-id

‘Ethernet Ping’: Specify destination MAC Address, VLAN and Maintenance Domain

Unicast frame (P802.1ag) or Unicast/Multicast frame (ITU Y.1731); Source must be a MEP, destination may be a MEP or a MIP; reply is unicast


Source DestinationCustomerEquipment

CustomerEquipment

Operator ABridges

Operator BBridges

MEP MEPMIPMIP

P802.1ag CFM ConceptsLink Trace (LTM, LTR; ITU: ETH-Trace)

Multicast message, source must be a MEP, destination must be a MEP too; reply is a unicastSpecify destination MAC Address, VLAN and Maintenance DomainAllows the discovery of all MIPs belonging to the same Maintenance Domain along the path to destination MEPHas TTL to limit propagation within networkOn each visible MIP indicate: Ingress Action, Relay Action, Egress Action

11 33 55Request Request Request

2244 66

Reply

ReplyReply

traceroute Ethernet {mac-address}{domain domain-name | level level-id} vlan vlan-id


P802.1ag – Connectivity Fault ManagementPutting Everything Together

1. Run Connectivity Check to detect a soft or hard failure

2. Upon a failure detection, use Loopback to verify it

3. Upon verification, run Traceroute to isolate it; multiple segment LPs can also be used to isolate the fault

4. If the isolated fault points to a virtual circuit, then the OAM tools for that technology can be used to further fault isolation—e.g., for MPLS PW, VCCV and MPLS ping can be used


ITU Y.1731Extensions over 802.1ag: Tools

ETH-LB: Ethernet Loopback—unicast and multicast

ETH-AIS: Alarm Indication Signal

ETH-Test: Test SignalTest bandwidth throughput, detect frame disorders, bit-errors, etc.

Bi- or Uni-Directional

PRBS patterns could be included

ETH-USR: Ethernet Maintenance ChannelRecently added, e.g. for performing remote management

ETH-APS: Ethernet Automated Protection SwitchingG.8031 (leverages ETH-AIS)


ITU Y.1731Alarm Indication Signal (ETH-AIS)

AIS is to proactively inform possibly all MEPs about a failure in the network

MEP response options include: always send AIS in-case of failure; only sent AIS in case of a MEP reported a failure; suppress further AIS propagation

AIS is multiplied (potentially to every VLAN and Level) and propagated upwards to domain hierarchy

AISAIS

AIS

To: NMS To: NMS

CustomerEquipment

CustomerEquipment

Operator ABridges

Operator BBridges

CustomerLevel

ProviderLevel

OperatorLevel


ITU Y.1731, MEFExtensions over 802.1ag: Performance Management

OAM for Performance Management

ParametersFrame Loss Ratio (currently P2P only, MP for further study)

Frame Delay (could use ETH-LB)

Frame Delay Variation

Availability

Errored Frame Seconds

Service Status

Frame Throughput

Frame TX/RX/Drop

Unavailable Time

Close alignment withIEEE P802.1ag andITU SG 13

Metrics and TLVs per performance management

Metrics for P2P EVCs:DelayDelay VariationFrame Loss

Metrics for MP EVCs (new!)Availability Metrics

MEF Performance Monitoring Project

ethernet oam overview: making ethernet manageable · link oam (ieee 802.3, clause 57) ethernet uni...

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