Accedian Networks - Ethernet OAM Overview.pdf



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Ethernet OAM OverviewOperations, Administration & Maintenance Standards critical services with high availability and QoS . Admin & Maintenance  OAM standards developed to make Ethernet carrier grade  Protocols developed to enable operationally efficient carrier Ethernet services over multi-vendor. capable of carrying real-time. multi-operator networks  Key Functions  Proactive network and service monitoring  Rapid fault detection & isolation  Performance / Service Level Agreement (SLA) parameters measurement: on-demand or continuously  Service usage measurement for billing & capacity management  When Deployed End-to-End  Ethernet becomes carrier grade.Ethernet Operations. topology-aware. multi-domain focused on single-hop links. reflected in SLAs Connectivity Link Network & service connectivity & performance monitoring.1731 802.1731.Ethernet OAM Standards Overview Demarcation Point 10/100/GbE Base TX / FX / LX / SX Customer Network Transport Network Customer Network Standards MEF & ITU-T Y.1ag. MEF IEEE 802. 1st mile transport . Y.3ah Access Core Access OAM Layer Service Connectivity Link OAM Layer Service Function / Focus end-to-end service (customer) view. g. link fault & critical events Fault isolation: customer or provider network. unidirectional failures Port-level loopback: remote or locally activated. power: dying gasp) Provider’s Network 1st Mile alarms  LOS (directional)  Critical events  Key      functions: Discovery: demarcation point device discovery & loopback capability Remote failure indication: dying gasp.802. disruptive Performance & Status Monitoring with threshold alarms . layer 1 only.Continuity stats  % frame errors  # coding symbol errors  Unrecoverable error (e.3ah Link Layer OAM  Designed for 1st mile / single-hop links  Typically Provider Edge (PE) to Customer Edge (CE)  Does not propagate beyond the link OAMPDUs: .Loopback . 1ag.3ah  IEEE 802. ITU-T Y. 802.1ag  Operator 2 Operator 3 .Connectivity & Service OAM Multi-Domain Network Model Provider Domain Operator A Bridges Operator B Bridges Maintenance Intermediate Point (MIP) Maintenance Endpoint (MEP) CPE CPE Customer OAM Level Layer 2 Data Path Provider OAM Level Operator OAM Level Link OAM End-to-End Ethernet Service OAM Access Links.1731 and MEF OAM standards are based on a common multi-domain network model Model reflects services delivered by multiple providers at different levels Goal is to ensure OAM is contained within pre-defined maintenance levels Customer Site 1 (fail-over link in grey) Service Demarc Customer Customer Site 2  Provider Operator 1 802. 1731)  Pt-to-Pt or Multipoint EVC .1ag) / Entity Group (Y.OAM Management Entities & Components Service Provider (S) Operator A Operator B S A A A A A A S A S B B B B B B B S B Operator A MEG A Operator A ME A S S B Acronym MEP MIP ME Description Maintenance Endpoint Maintenance Intermediate Point Management Entity (relationship between 2 MEPs) Maintenance Intermediate Point (MIP) Maintenance Endpoint (MEP)  Logical Group of MEs   at same level on same S-VLAN MA / MEG Maintenance Assc (802. throughput measurement) NOC EVC Failure CCM Alarm 802.802.1731 Connectivity Fault Management (CFM) Fault Detection using Continuity Check Messages CCM Timeout Alarms Fault Verification Using Loopback Messages (“Ping”) Can also be used to loopback a test traffic stream (e.1ag / Y. Alarm Indication Signal (Y.1731 Unicast & multicast EVC Failure LBM LBR Fault Isolation Using Linktrace Messages Fault Notification.g.1731 only) Per Service Alarms EVC Broken Link LTM LTR EVC Broken Link AIS .1ag Unicast only Y. 1-Way Synchronized Clocks 1DM time-stamped packets EVC Broken Link CCM Tx / Rx Counters Frame Delay (FD) / Delay Variation (FDV) Measurements.1731 Performance Monitoring (PM) Frame Loss Ratio Using CCM (dual-ended) Frame Delay (FD) / Delay Variation (FDV) Measurements. Round-Trip   DMM time-stamped packet sent to far-end Far-end device responds with DMR carrying original timestamp Originating device compares timestamp to current time to calculate delay No clock-sync required between endpoints DMM DMR EVC DMM DMR   .Y. 1731 only . DMM / DMR             Fault Verification / Loopback CFM Fault Isolation Discovery Fault Notification Frame Loss PM Frame Delay Delay Variation  Accedian Networks has also developed in-service throughput testing based on Y.1731 LBM / LBR frames (patent pending) * Y.1731 Method CCM LBM / LBR (“Ping”) LTM / LTR LTM / LTR & Multicast LBM* AIS / RDI CCM.1ag Y. DMM / DMR DM (1 way). LTM / LTR DM (1 way).Connectivity & Services OAM Summary OAM Function Fault Detection 802. fault propagation beyond 1st mile (link faults not sent end-to-end).3ah or no OAM Provider’s Network CPE 802.3ah or no OAM CPE Demarcation Point Demarcation Point Provider’s Network CPE 802.1731 OAM CPE  802.3ah lacks: performance monitoring.3ah (link OAM) not interoperable with 802.1ag / Y.1ag / Y.1731 into Service Endpoints 802.1ag/Y.1ag / Y.1731 OAM functionality end-to-end   .1731 OAM 802. L2/3 & per-flow traffic loopback.1731 (Connectivity OAM) some vendor-specific methods & emerging MEF 17 standard 802. NIDs enable 802. link trace & loopback response for fault verification & isolation.Incorporating 802.1ag / Y. NE-based Ethernet OAM/PM currently unusable for throughput verification. standards-based Ethernet OAM/PM often brought-in to the rescue MSC / BSC . Aggregation Network Elements having a hard time computing high-accuracy/high granularity one-way OAM/PMs for several 100s of flows on a single high speed port. Aggregator     Forklift upgrades often required Service Assurance vendors supporting advanced.Ethernet OAM is a good start but not sufficient Challenging OAM PERFORMANCE of  High speed/high capacity pipes with 100s of service flows handed-off at MSCs. Over 100 remote base stations homing into the MSC  Ethernet OAM/PMs is often only supported on a per-port or low-count VLAN basis and only in a round-trip fashion. a key SLA component Provider’s Network Single 1G or 10G pipe with hundreds of service flows. OAM in access platforms limits visibility of the problematic “last mile”. delay added to loopback traffic. Many access platforms do not support advanced rate limiting. NEs OAM Function Implementation Delay / Delay Variance Measurement One-Way Delay Measurements Multi-Flow Monitoring Software based implementation (network processor) ~1 ms resolution.Deploying 802. traffic conditioning & OAM alignment 802. EIR up to full wire-speed In-line. leaving this segment unmanaged. filtering and shaping to optimize QoS. Loopback Testing Frame Loss Measurement OAM Uniformity over Multi-Vendor / Carrier / Technology Networks Service creation. variable accuracy not sufficient to monitor real-time services and SLAs Typically only provides round-trip measurements. Enables an overlay of the latest .1ag / Y. NIDs provide service mapping. in-service throughput testing of CIR. No throughput testing.orders of magnitude more precise than Synthetic measurements. multi-service and multicast configurations. Up to 100 Concurrent Flows / SLAs with no performance hit Hardware-based architecture enables advanced. OAM and conditioning at the service demarc for complete end-to-end coverage.1731 Reach OAM enabled in NIDs at the demarc point provide connectivity and service OAM visibility directly to the customer site . NEs can monitor “A Few Flows” varies by network element & traffic load Limited OAM loopback packet processing capacity. full OAM functionality and advanced complementary testing end-to-end without network element upgrades OAM should be established at the service endpoints to provide valid results. hardware-based. SLAs commonly specify one-way delay requirements.1ag/Y. OAM version and feature support uneven. RFL is required to validate high-performance SLAs. Dedicated silicon packet processing. multi-site. hardware-based packet processing provides Real Frame Loss (RFL) .1731 using NIDs vs. Standards provide “synthetic” frame loss based only on OAM frames Interoperability. real-time 1 μs delay / jitter measurement resolution with < 20 μs accuracy Provides both one-way and round-trip measurements in multi-flow. OAM CFM provides operational efficiency. end-toend service management over any network topology. .Ethernet OAM. rapid perservice fault identification. Establishing OAM using NIDs provides uniform. Conclusions  Establishing end-to-end OAM is a key part of delivering high-performance.      Hardware-based NIDs also enable highly scalable service creation and assurance functionality directly at the service endpoints. Standards are evolving: multi-vendor interoperability issues and varying levels of feature support is common. carrier-grade Ethernet services. verification and isolation for high availability services over multi-operator networks. OAM Performance Monitoring provides means to monitor and report key SLA and service usage metrics.
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