ethernet oam overview: making ethernet manageable · link oam (ieee 802.3, clause 57) ethernet uni...
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© 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
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 3
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
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 4
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
Operator 4Operator 4
Service ProviderService Provider
CustomerCustomer
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 5
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
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 6
Ethernet Physical OAM & LMI
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 7
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
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 8
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
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 9
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
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 10
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
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 11
EEE P802.1ag Connectivity Fault ManagementITU Y.1730, Y.1731MEF 9
Service OAM and Assurance
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 12
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
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 13
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
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 14
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 3Operator 3
Operator 4Operator 4Service ProviderService Provider
CustomerCustomer
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 15
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
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 16
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
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 17
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
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 18
CCM – Parameters & Performance
Source: IEEE 802.1ag, D8.1
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 19
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
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 20
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
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 21
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
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 22
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)
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 23
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
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 24
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
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 25
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