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 Traffic

Premium Real Time VoIP, Video

Gold Priority Data Business Data

Standard 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 CoS

Frame Delay (ms) ≤ 10 ≤ 20 ≤ 37

Delay Variation(IFDV) (ms)

≤ 3 ≤ 8 N/S

Frame Loss (%) ≤ 0.01 ≤ 0.01 ≤ 0.1

Availability 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 CoS

Frame Delay Percentile 99.9th 99th 95th

Time Interval ≤ Month ≤ Month ≤ Month

Delay Variation(IFDV)

Percentile 99.9th 99th N/S

Time Interval ≤ Month ≤ Month N/S

Frame Loss Time Interval ≤ Month ≤ Month ≤ Month

Availability 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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