Slide 1

Carrier Ethernet – The CIO PerspectivePart II: Service Levels and SLAs

RAD Data CommunicationsJune 2011

Slide 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– Restrictions – Credits/SLA violation remedies– Etc…

Slide 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

Slide 4

Carrier Ethernet SLAs – CoS, QoS and KPIs

• Each level requires differentiated SLA with 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

Service Levels Classes of Service TrafficPremium Real Time VoIP, VideoGold Priority Data Business DataStandard Best Effort Internet

Slide 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

Slide 6

KPI Performance Objectives

KPI Performance Objectives, Business Services* (MEF 23.1 Draft):

High CoS Medium CoS Low CoSFrame Delay (ms) ≤ 10 ≤ 20 ≤ 37Delay Variation(IFDV) (ms)

≤ 3 ≤ 8 N/S

Frame Loss (%) ≤ 0.01 ≤ 0.01 ≤ 0.1Availability TBD TBD TBD

* Metro, point-to-point

Slide 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):

High CoS Medium CoS Low CoSFrame Delay Percentile 99.9th 99th 95th

Time Interval ≤ Month ≤ Month ≤ MonthDelay Variation(IFDV)

Percentile 99.9th 99th N/S

Time Interval ≤ Month ≤ Month N/S

Frame Loss Time Interval ≤ Month ≤ Month ≤ MonthAvailability TBD TBD TBD TBD

Slide 8

Monitoring and Reporting: Are You Getting the SLA You’re Paying For?

Slide 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

Slide 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 detection and 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

Slide 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

Slide 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

Service Turn-up

On-going Monitoring

Fault Management & Recovery

Slide 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

Slide 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)?

Slide 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?

Slide 16

Thank You For Your Attention

www.rad.com

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