802.1ag - CFM Tutorial - Part 1 v2
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802.1ag - Connectivity Fault Management Tutorial – Part 1 Dinesh Mohan July 12, 2004
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Transcript of 802.1ag - CFM Tutorial - Part 1 v2
802.1ag - Connectivity Fault ManagementTutorial – Part 1
Dinesh MohanJuly 12, 2004
802.1ag – Connectivity Fault Management Tutorial – Part 1 (Jul 12, 2004) [Dinesh Mohan] - 2
802.1ag PAR Overview
802.1ag – Connectivity Fault Management Tutorial – Part 1 (Jul 12, 2004) [Dinesh Mohan] - 3
802.1ag Scope
• “This standard specifies protocols, procedures, and managed objects to support transport fault management. These allow discovery and verification of the path, through bridges and LANs, taken for frames addressed to and from specified network users, detection, and isolation of a connectivity fault to a specific bridge or LAN”
802.1ag – Connectivity Fault Management Tutorial – Part 1 (Jul 12, 2004) [Dinesh Mohan] - 4
802.1ag Purpose
• “Bridges are increasingly used in networks operated by multiple independent organizations, each with restricted management access to each other’s equipment. This standard will provide capabilities for detecting, verifying and isolating connectivity failures in such networks”
802.1ag – Connectivity Fault Management Tutorial – Part 1 (Jul 12, 2004) [Dinesh Mohan] - 5
802.1ag Reason for Standardization
• Growing interest in the use of Fault Management tools within enterprise and provider networks
• Such tool needed for established operational practices
• Existence of similar tools e.g. – ATM’s “continuity check”, “Loopback” and “multiple Loopback” and – IP’s “ping” and “traceroute”
• Interest and activities within ITU-T and MEF have further highlighted the need for these fault management tool
802.1ag – Connectivity Fault Management Tutorial – Part 1 (Jul 12, 2004) [Dinesh Mohan] - 6
OAM Framework
802.1ag – Connectivity Fault Management Tutorial – Part 1 (Jul 12, 2004) [Dinesh Mohan] - 7
Ethernet OAM Layering
CE U-PE U-PEN-PEN-PE CEB B P P P PDevice View
Ethernet Layer
Eth Access MPLS Core MPLS Access
Customer CustomerService Provider
• Example: network/service with Ethernet & other technologies
• The Ethernet Layer implies the visibility to Ethernet frames– BUT Flat! Difficult to manage and identify accountability
802.1ag – Connectivity Fault Management Tutorial – Part 1 (Jul 12, 2004) [Dinesh Mohan] - 8
OAM Domain – Service/Network
Eth Access MPLS Core MPLS Access
Customer CustomerService Provider
Customer Domain
Provider Domain
Operator Domain Operator Domain
Operator Domain
• Solution: OAM Domains
• Domains necessary to bound OAM Flows & OAM responsibilities
802.1ag – Connectivity Fault Management Tutorial – Part 1 (Jul 12, 2004) [Dinesh Mohan] - 9
Maintenance Entity Points (MEP) & Maintenance Intermediate Points (MIP)
Network OAM
Service OAM
Customer Domain
Provider Domain
Operator Domain Operator Domain
Operator Domain
Eth Access MPLS Core MPLS Access
Customer CustomerService Provider
MPLS Domain MPLS Domain
Maintenance Entity PointMaintenance Intermediate Point
PW/MPLS OAM
• MEPs initiate/terminate/react to all OAM flows• MIPs react to some OAM flows [Optional]• MEPs & MIPs dependent on Business Models & Deployment Scenarios
802.1ag – Connectivity Fault Management Tutorial – Part 1 (Jul 12, 2004) [Dinesh Mohan] - 10
Ethernet MEPs & MIPsCustomerEquipment
CustomerEquipment
Operator ABridges
Operator BBridges
ETH
ETY
1 2 3 4 5 6 7 8 9
• Another representation for positioning of MEPs and MIPs on devices with consideration for ingress and egress.
Maintenance Entity PointMaintenance Intermediate Point
802.1ag – Connectivity Fault Management Tutorial – Part 1 (Jul 12, 2004) [Dinesh Mohan] - 11
Maintenance Entities Mapped
• Example MEs identified– 2 Service Providers (SP1 & SP2)– SP2 has two domains (operators)– MEs 1,2,3,4 are required for Business relationship– MEs 5,6 are required for convenience
Customer CustomerService Provider
1. UNI_C-UNI_C ME2. UNI_N-UNI_N ME3. UNI ME 3. UNI ME
SP 1 SP 2 SP 2
4. E-NNI ME5. Inter-domain ME (SP)
6. Intra-domain ME 6. Intra-domain ME6. Intra-domain ME (Operator)
UNI UNIE-NNI
802.1ag – Connectivity Fault Management Tutorial – Part 1 (Jul 12, 2004) [Dinesh Mohan] - 12
End-to-end OAM – 2 Models
• Provider End-to-end OAM? CE-CE (terminating UNIs)– 2 Possible Models
Strong-Trust E-NNI• ME (3) + ME (2) + ME (3)
Weak-Trust E-NNI• ME (3) + ME (6) + ME (4) + ME (5) + ME(3) or• ME (3) + ME (6) + ME (4) + ME (6) + ME(3)
Customer CustomerService Provider
1. UNI_C-UNI_C ME2. UNI_N-UNI_N ME3. UNI ME 3. UNI ME
SP 1 SP 2 SP 2
4. E-NNI ME5. Inter-domain ME (SP)
6. Intra-domain ME 6. Intra-domain ME6. Intra-domain ME (Operator)
UNI UNIE-NNI
802.1ag – Connectivity Fault Management Tutorial – Part 1 (Jul 12, 2004) [Dinesh Mohan] - 13
Maintenance Entities – P2P Case
• All MEs may not be needed always
• MEPs realize Maintenance Entities (MEs)
ETH_TFPETH_FP ETH_FP
ETHFPPLink ETH_FP
ETH_TFPETH_FP
ETHFPPLink
Service provider YUser X User X
UNI_C to UNI_C maintenance entity
UNI_N to UNI_Nmaintenance entity
IntraDomain ME
UNI UNI
Access Link ME Access Link ME
NetworkOperator B
ETHFPP Link
NNI
InterDomain ME
IntraDomain ME
NetworkOperator AETH_TFP
ETH_FP ETH_FP
ETHFPPLink ETH_FP
ETH_TFPETH_FP
ETHFPPLink
Service provider YUser X User X
UNI_C to UNI_C maintenance entity
UNI_N to UNI_Nmaintenance entity
IntraDomain ME
UNI UNI
Access Link ME Access Link ME
NetworkOperator B
ETHFPP Link
NNI
InterDomain ME
IntraDomain ME
NetworkOperator A
802.1ag – Connectivity Fault Management Tutorial – Part 1 (Jul 12, 2004) [Dinesh Mohan] - 14
Maintenance Entities – MP2MP Case
ETH_TFPTH_FP ETH_FP
ETHLink ETH_FP ETH_FP
ETHLink
ETH_TFPETH_FPETH
Link
ETH_FPETHLink
Service Provider Y
Network Operator BNetwork Operator AUser X User X
UNI NNI UNI
UNI
ETH_TFPETH_FP
ETH_TFPETH_FP ETH
Link
UNI
ETH_FP ETH_FP
UNI_C to UNI_C maintenance entities
UNI_N to UNI_N maintenance entities
Intra Domain MEs Intra Domain MEs
Access Link MEs Access Link MEsInter Domain ME
ETH ETH
• All MEs may not be needed always
• MEPs realize Maintenance Entities (MEs)
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Maintenance Entities – CPE based Network Demarcation Access
• All MEs may not be needed always
ETH_FP
Service. Provider YNetwork Operator B
User X
UNI_C to UNI_C ME
UNI_N to UNI_N ME
Access Link ME
ETH_TFP ETH_FP
User X
Access Link ME
Extension Link ME
User Location
UNI_NP to UNI_NP ME
UNI ETH_FP
ETH Link
Private NNI
ETH_FP
Network Operator A
ETH Link
NNIETH_FP ETH_FP ETH_FP
ETH FPP Link
UNI
ETH FPP Link
ETH_TFP ETH_FP
NDD
802.1ag – Connectivity Fault Management Tutorial – Part 1 (Jul 12, 2004) [Dinesh Mohan] - 16
Maintenance Entities – CPE based Network Demarcation Access
• All MEs may not be needed always
1 2 3 4 5 6 7 8 9
ETH_FP
Service. Provider YNetwork Operator B
User X
ETH_TFP ETH_FP
User X
User Location
UNI ETH_FP
ETH Link
Private NNI
ETH_FP
Network Operator A
ETH Link
NNIETH_FP ETH_FP ETH_FP
ETH FPP Link
UNI
ETH FPP Link
ETH_TFP ETH_FP
NDD
NDD
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Service/Network OAM – How does it come together?
Ethernet link OAM
PW/MPLSOAM
EoSONET OAM
Other OAM
Network OAM
Service OAM
Transport Links
Network
Services
• OAM Interworking possible to utilize OAM across Layers
• However, each layer must support OAM capabilities independently
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Connectivity Fault Management Functions
802.1ag – Connectivity Fault Management Tutorial – Part 1 (Jul 12, 2004) [Dinesh Mohan] - 19
CFM Functionality
• a) CC – Continuity Check• Multicast unidirectional heartbeat • Use: Fault Detection
• b) Loopback• Unicast bi-directional request/response• Use: Fault detection, verification
• c) Traceroute• Multicast request/unicast responses• Use: Fault Isolation
802.1ag – Connectivity Fault Management Tutorial – Part 1 (Jul 12, 2004) [Dinesh Mohan] - 20
Other OAM Functionality (out of scope for .1ag)
• d) Discovery– i) Service
• e.g. discover all PEs supporting common service instance
– ii) Network• e.g. discover all devices (PE and P) common to a domain
• e) AIS/RDI• Use: E<->W Fault propagation, Alarm Suppression
• f) Performance Management
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CFM Functions mapped to MEs
Customer CustomerService Provider
1. a, b, c2. a, b, c
• Note: Specifically for ME (3) and ME (4)– IEEE 802.3ah OAM can be used for network/link OAM when UNI/E-NNI is an Ethernet link– When single service carried across a link, network OAM can map to service OAM
3. a, b, c, e
SP 1 SP 2 SP 2
3. a, b, c4. a, b, c
5. a, b, c
6. a, b, c 6. a, b, c6. a, b, c
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Summary
• Ethernet moving into Provider Networks
• Providers require fault management tools to manage their networks
• High Industry interest in Ethernet connectivity fault management tools
