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Ce the cio perspective part ii v2 3 21-6-11
Ce the cio perspective part ii v2 3 21-6-11
Ce the cio perspective part ii v2 3 21-6-11
Ce the cio perspective part ii v2 3 21-6-11
Ce the cio perspective part ii v2 3 21-6-11
Ce the cio perspective part ii v2 3 21-6-11
Ce the cio perspective part ii v2 3 21-6-11
Ce the cio perspective part ii v2 3 21-6-11
Ce the cio perspective part ii v2 3 21-6-11
Ce the cio perspective part ii v2 3 21-6-11
Ce the cio perspective part ii v2 3 21-6-11
Ce the cio perspective part ii v2 3 21-6-11
Ce the cio perspective part ii v2 3 21-6-11
Ce the cio perspective part ii v2 3 21-6-11
Ce the cio perspective part ii v2 3 21-6-11
Ce the cio perspective part ii v2 3 21-6-11
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Ce the cio perspective part ii v2 3 21-6-11


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  • 1. Carrier Ethernet – The CIO PerspectivePart II: Service Levels and SLAs
    RAD Data CommunicationsJune 2011
  • 2. What’s in an SLA?
    A business-grade SLA for Carrier Ethernet services will typically include the following:
    Connection rates
    Class of Service (CoS) levels definition and traffic priority settings
    Bandwidth commitments per CoS
    Quality of Service (QoS) KPI (Key Performance Indicators) guarantees
    Monitoring and reporting
    Service and support hours, response and repair times
    Credits/SLA violation remedies
  • 3. Carrier Ethernet SLAs Throughput Guarantees
    CIR: Committed Information Rate. Bandwidth with guaranteed delivery, regardless of network conditions
    EIR: Excess Information Rate. The bandwidth allowance depending on network resource availability
    PIR: Peak Information Rate; CIR+EIR – defines the maximum bandwidth allowed
  • 4. Carrier Ethernet SLAs – CoS, QoS and KPIs
    Each level requires differentiated SLAwith appropriate QoS parameters to ensure user QoE (Quality of Experience)
    “Bursting” is the ability to exceed the designated bandwidth for a short period to avoid traffic dropping
  • 5. Key service elements that directly effect QoE
    Availability: Network uptime on a monthly basis, after measuring the number of minutes and seconds that the service was unavailable to the enterprise
    Business-grade SLA: 3-5 Nines (99.9% -99.999%), depending on CoS
    Latency: The time for transmitting a packet/frame of data from a source to its destination
    Effect on voice traffic: Delays, overlapping speech, echo
    Effect on video traffic: From blanks to session termination
    Jitter: The difference in delay between two consecutive frames/packets
    Effect on Voice: Static, distorted speech
    Effect on video: Momentary signal loss, shaky image
    Loss: Percentage of undelivered frames out of all sent frames
    Effect on data: requires re-transmissions which lower throughput
    Effect on video: Momentary signal loss, graininess, session termination
    MTTR: Mean Time to Repair
  • 6. KPI Performance Objectives
    KPI Performance Objectives, Business Services* (MEF 23.1 Draft):
    * Metro, point-to-point
  • 7. KPI Performance Parameters
    An SLA should specify how parameter values are measured: The percentage of traffic to which the guarantee is applicable, over what time interval, etc (MEF 23.1 Draft):
  • 8. Monitoring and Reporting: Are You Getting the SLA You’re Paying For?
  • 9. Monitoring and Reporting: What You Should Look for?
    Choose a service provider that can provide performance reports:
    Monitor the service
    Compare actual performance to the SLA you buy
    Get service credits when the service provider fails to deliver
    Change service provider if failures are repeated
    Different reporting options:
    Periodical (weekly/monthly)
    Self-managed 24x7 portals: View KPI data in real-time
  • 10. Service Provider Tools to Guarantee Carrier Ethernet SLAs
    Service providers can now implement the following capabilities in their networks:
    Traffic and bandwidth management for multilevel QoS
    Performance monitoring and reporting
    Fault detectionand repair
    Resiliency and protection
    In order for these attributes to be effective, they need to be implemented at the service hand-off point, i.e., in the service provider’s CPE (also called Ethernet demarcation) installed at customer premises
  • 11. Multi-CoS Traffic Management Tools
    Traffic classification according to enterprise preference and equipment (e.g., IP Precedence, address, VLAN Priority bit, etc)
    Advanced traffic mapping to ensure QoS adherence and transparency of user classification over the WAN
    Rate metering and policing per CIR/EIR profiles for multi-flow Ethernet connections (i.e., different profiles over the same link)
    Hierarchical scheduling for multi priority traffic
    Traffic shaping and queue management to avoid packet dropping and congestion
    CoS 7 = Management
    CoS 6 = VoIP
    CoS 5 = Video
    CoS 4 = Interactive
    CoS 3 = Priority Data
    CoS 2 = Other Data
    CoS 1 = Best Effort
    CoS 0 = Best Effort
    An 8-CoS Traffic Queue
  • 12. Service Lifecycle Management Tools
    An elaborate set of tools to provision, monitor and control Ethernet services at turn-up, as well as for on-going monitoring and fault management
    Specific standardized tests to continuously evaluate SLA performance metrics and report results/statistics to network management system (OSS/BSS)
    Shorten lead-times for fault identification and resolution to avoid service disruptions
    Identify trends and take preventive measures before service and users are affected
  • 13. Resiliency and Protection Tools
    Ensure High Availability and speedy restoration by protecting the links, as well as the entire service path
    Standardized redundancy schemes:
    Link Aggregation: Parallel connections are bundled to a single virtual link
    Ethernet Linear Protection Switching: Redundancy at the service path level with an EVC (Ethernet Virtual Connection) backup
    Ethernet Ring Protection Switching: Ring protection with fast failover
    Without proper protection mechanisms QoE is compromised due to retransmissions or even loss of service
  • 14. Additional Questions to the Service Provider
    Is the Ethernet service certified by the MEF (Metro Ethernet Forum)?
    Can the service provider guarantee service consistency even when some locations are not fiber-fed?
    Can the service provider guarantee service consistency even for out of footprint locations (e.g., on a national and global scale)?
    How accurate are the link quality and service performance measurements?
    How many provider boxes need to be installed at the premises (e.g., CPE/demarcation and test probes)?
  • 15. In Conclusion
    Carrier Ethernet SLAs should include specific definitions of service levels and guarantees for key performance indicators
    Service KPIs directly effect how users experience application performance. KPI metrics differ by provider, but industry standardization efforts are under way
    Getting SLA reports ensures you get what you paid for
    Business-grade services require smart Ethernet demarcation devices to be installed at customer premises
    Check out other installments in the series:
    Part I: Why Choose Carrier Ethernet WAN Services?
    Part III: Ethernet and IP VPNs, When to Use Which?
  • 16. Visit for more information