Ethernet OAM Overview. Dinesh Mohan Nortel Networks Oct 15, 2004

Transcription

1 Ethernet OAM Overview Dinesh Mohan Nortel Networks Oct 15, 2004

2 What is OAM? Management Environment (EMS/NMS) NEs & Networks N S <- > E <-> W Data Store OAM is both E <-> W and N <-> S E <-> W Requirements guided by N <-> S Ethernet OAM focus is E <-> W (across NEs) Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #2

3 Ethernet OAM Framework Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #3

4 Ethernet OAM Scenario Customer Service Provider Customer Eth Access MPLS Core MPLS Access Device View CE U-PE B B N-PE P P P N-PE P U-PE CE Layer Example scenario: Network with Ethernet & other technologies running Ethernet Service Layer implies visibility of Ethernet frames Scenario involves different Administrations Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #4

5 OAM Domains Service/Network Customer Service Provider Customer Eth Access MPLS Core MPLS Access Customer Domain Provider Domain Operator Domain Operator Domain Operator Domain Customer contracts end-to-end Service with Provider; Provider contracts Facilities (network) with Operator(s) Manageability responsibility should be clearly demarcated OAM Domains facilitate manageability & accountability OAM Domains can Nest but not Overlap OAM should be prevented from leaking between Domains Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #5

6 Maintenance End Points (MEP) & Maintenance Intermediate Points (MIP) Customer Service Provider Customer Operator Domain Maintenance End Point Maintenance Intermediate Point Eth Access MPLS Core MPLS Access Customer Domain Provider Domain Operator Domain MPLS Domain Operator Domain MPLS Domain MEPs are provisioned and initiate/terminate/react to OAM Flows; MIPs react to some OAM Flows MEPs & MIPs are dependent on Business Models & Deployment Scenarios Both Service OAM and Network OAM are applicable Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #6 PW/MPL S OAM Service OAM Network OAM

7 Ethernet OAM MEPs & MIPs Customer Equipment Operator A Bridges Operator B Bridges Customer Equipment ETY or SRV MEPs and MIPs mapped to ingress/egress Ethernet ports of Ethernet aware devices ETY refers to Ethernet PHY links; SRV refers to emulated links e.g. EoSONET, EoMPLS/PW Port can have multiple MEPs but only one MIP Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #7

8 Ethernet OAM MEs & ME Levels Customer Equipment Operator A Bridges Operator B Bridges Customer Equipment UNI_C to UNI_C ME UNI ME UNI_N to UNI_N ME UNI ME Operator ME NNI ME Operator ME ETY or SRV Segment ME Pair of MEPs form Maintenance Entity (ME) Same OAM mechanisms should be available in each OAM Domains transparently Inter-domain ME needed e.g. UNI ME transcends Customer & Provider; NNI ME transcends Providers or Operators ME Levels differentiate between OAM Frames belonging to different OAM Domains Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #8

9 Ethernet OAM ME Level Assignments Customer Equipment Operator A Bridges Operator B Bridges Customer Equipment UNI_C to UNI_C ME UNI ME UNI_N to UNI_N ME UNI ME Operator ME NNI ME Operator ME ETY or SRV Segment ME Total of 8 ME Levels agreed for Ethernet OAM 3 ME Levels (7,6,5) for Customer OAM Domain; 2 ME Levels (4,3) for Provider OAM Domain; 3 ME Levels (2,1,0) for Operator OAM Domain Inter-domain ME Level defaults: UNI ME Level (4); NNI ME Level (2); However, Inter-domain ME Level is negotiable between involved domains. Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #9

10 Example MEs (Point-to-point Case) Service provider Y User X _TFP _FP FPP Link Network Operator A _FP FPP Link Network Operator B FPP _FP Link User X _TFP _FP UNI NNI UNI UNI_C to UNI_C maintenance entity UNI_N to UNI_N maintenance entity Intra Domain ME Intra Domain ME Access Link ME Inter Domain ME Access Link ME Actual ME used are dependent on Business Models & Deployment Scenarios Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #10

11 Example MEs (Multipoint Case) User X _TFP TH_FP _TFP _FP Service Provider Y Network Operator A Network Operator B Link _FP _FP Link _FP _FP Link UNI NNI UNI Link UNI _FP _FP Link UNI User X _TFP _FP _TFP _FP UNI_C to UNI_C maintenance entities UNI_N to UNI_N maintenance entities Intra Domain MEs Intra Domain MEs Access Link MEs Inter Domain ME Access Link MEs Actual ME used are dependent on Business Models & Deployment Scenarios Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #11

12 Example MEs (Alternate Access Scenario) User Location User X FPP Link NDD Network Operator A Link Service. Provider Y Network Operator B Link FPP Link User X _TFP _FP UNI _FP _FP Private NNI _FP _FP _FP _FPUNI _TFP NNI _FP Access Link ME UNI_C to UNI_C ME UNI_N to UNI_N ME Extension Link ME UNI_NP to UNI_NP ME Access Link ME NDD is network demarc, service unaware device This is a commonly used CPE deployment OAM is extensible even across such scenarios Actual ME used are dependent on Business Models & Deployment Scenarios Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #12

13 Service & Network OAM How diff. layers come together? Services Service OAM Network Network OAM Facility Links Ethernet link OAM PW/MPLS OAM EoSONET OAM Other OAM Model is iterative; Service can be a Link e.g. For VPLS, MPLS PW is single hop link Each layer MUST support OAM independently OAM Interworking across layers is possible Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #13

14 Ethernet OAM Functions Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #14

15 OAM Functions: Fault Management Typical Fault Management Steps Fault Detection Fault Verification Fault Isolation Fault Notification Fault Recovery Specific OAM Mechanisms (work in progress) Fault Detection Continuity Check (-CC) Fault Verification Loopback (-LB) Fault Isolation Link Trace (-LT) Fault Notification AIarm Indication Signal (-AIS) Fault Recovery RSTP, Link Aggregation, -PS Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #15

16 OAM Functions: Performance Management Typical Performance Management Steps Definition of Performance Parameters Collection of Performance related Data Measurement of Performance Parameters Determination of Service/Network Level Agreement Compliance Specific OAM Mechanisms (work in progress) Performance Collection for Performance Parameters Frame Delay Frame Delay Variation Frame Loss Availability Performance Measurements Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #16

17 Ethernet Layer Example Network (for OAM Function Discussion) CE1 PE1 P1 P2 P3 PE2 PE4 CE2 CE4 Focus of this example on Service Provider OAM Domain for Service OAM Ports P3 3 & P1 3 blocked (manually or via RSTP) to prevent loops; Links P2 2 -P3 3 & P1 3 -P2 1 blocked as a result 2 example services Point-to-point S12 (CE1-CE2) Multipoint S134 (CE1-CE3-CE4) PE3 CE3 Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #17

18 Ethernet OAM Generic Frame Format (current view work in progress) Each OAM Frame is expected to have the following OAM specific elements: ME Level OpCode Service Identifier Sender s MEP Identifier Transaction/Sequence ID Timestamp Ver VLAN Tag Destination MAC Source MAC EtherType (VLAN) EtherType (OAM) ME Level OpCode Hdr Length Transaction/Sequence Identifier Transmission Timestamp (Fixed Hdr may be extended in future) Service Id TLV Other TLVs ME Level identified Customer/Provider/Operator OpCode identifies specific OAM Function Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #18

19 Continuity Check (-CC) (work in progress) CE1 PE1 P1 P3 PE2 CE2 P2 PE4 CE4 PE3 CE3 Allows MEPs to determine connectivity with peer MEPs, where peer MEPs are part of same service in same OAM Domain Each MEP sends a periodic multicast CC message Each MEP receives periodic CC messages from peer MEPs Failure to receive N consecutive CC messages from a peer MEP, is declared as loss of connectivity with the peer MEP -CC allows un-solicited discovery of peer MEPs, and allows MEP to learn MAC addresses of peer MEPs Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #19

20 Loopback (-LB) (work in progress) CE1 PE1 P1 P2 P3 PE2 PE4 CE2 CE4 Unicast Loopback MEP sends a Unicast Loopback Request message to a peer MEP; Receiver MEP replies with a Unicast Loopback Reply message Upon Failure Detection via CC, -LB can be used to verify Failure Multicast Loopback MEP sends a Multicast Loopback Request message; peer MEPs reply with a Unicast Loopback Reply messages with random delay Multicast -LB can be used for solicited discovery of peer MEPs Multicast -LB can also be used for diagnostics Intrusive Loopback is also under discussion PE3 CE3 Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #20

21 Link Trace (-LT) (work in progress) CE1 PE1 P1 P2 P3 PE2 PE4 CE2 CE4 MEP sends a Multicast Linktrace Request message for a target peer MEP; Receiver MIP that knows about target peer MEP replies with a Unicast Linktrace Reply AND forwards a new Multicast Linktrace Request towards target peer MEP with information about the originating MEP and vector distance from that originating MEP; target peer MEP replies with a Unicast Linktrace Reply. Originating MEP establishes Path (sequence of MIPs and MEP) to the target MEP based on replies and vector PE3 CE3 Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #21

22 Customer Equipment Alarm Indication Signal (-AIS) (work in progress) Operator A Bridges Operator B Bridges Customer Equipment Service ETY X Client-Server relationship applies across OAM domains Server Layer detect failure; Server Layer MEPs transmit AIS towards Client Layer MIPs; Client Layer MIP forwards AIS towards Client Layer MEPs; this can iterate AIS useful for Alarm Suppression at Client Layer and optionally to trigger Protection Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #22

23 Performance Management (work in progress) CE1 PE1 Data path MOs in Management plane Data path MO used to make measurements Data path MO values written into OAM frame via management plane Accurate for p2p; No hardware upgrade needed Data path MOs in Data plane Data path MO values written into OAM frame via data plane Increased accuracy for p2p; hardware upgrade needed Statistical Sampling Sampling performed to predict data path behavior; P1 P2 Least accurate; may apply to mp2mp until mp Traffic Management P3 PE3 PE2 CE2 PE4 CE4 CE3 Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #23

24 Ethernet OAM Standardization Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #24

25 Where is Ethernet OAM being Standardized? Standard Organizations Ethernet OAM [E<>W, N<>S] Link OAM [E<>W] IEEE 802.3ah Fault Mgmt [E<>W] IEEE 802.1ag MIBS IEEE EMS/NMS [N<>S] EMS-NMS Info Model Service OAM [E<>W] Performance Mgmt Ethernet OAM [E<>W] Q.3/SG13 Ethernet Protection Q.3/SG13 FCAPS/FAB SG4 VPLS OAM [E<>W] L2VPN WG VPWS OAM [E<>W] PWE3 WG EMS/NMS [N<>S] MTMN Ethernet OAM Overview (Dinesh Mohan Oct 15, 2004) #25

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