bandwidth management and qos

Bandwidth Management and QoS

Shane Duffy

MEF Carrier Ethernet Certified Professional

Basic history

• Circuit switched to Packet switched networks

• Circuit

– Dedicated circuit always provisioned from end to end

• Packet Switched

– Allows better sharing and balancing of resources while scaling.

Terminology I

• Bandwidth Management is the process of controlling packets on a network link– To avoid overfilling the link which would result in

network congestion

• Bandwidth Management may be referred to as:– Bandwidth Control

– Bandwidth Throttling

– Rate limiting

– Token Bucket

– Leaky Bucket

LAN to [ internet | WAN ]

Internet | WAN

Like a fire hose VS a garden hose

LAN to [ internet | WAN ]

QoS

• How do I make sure Business email gets priority over Youtube.

• What services are impacted by network performance

Terminology II

• QoS is a resource reservation system– Its not a measure of achieved quality or a guarantee

of quality– It’s a work around for congestion– Its especially important with latency sensitive

applications

• QoS (Quality of Service) may be referred to as:– DSCP (Differentiated services code point)– ToS (Type of Service)– IntServ (Integrated Services)

Questions

Next section can get really technical

Technical Session

• Leaky Bucket

• Token Bucket

• Multiple Buckets

• Egress & Ingress (Where to implement?)

• Carrier Ethernet

• QoS

Leaky Bucket

Packets are discarded when the bucket is full

Token Bucket

Looks almost the same? Lets discuss

Leaky VS Token Bucket

• LB discards packets; TB does not. TB discards tokens.

• With TB, a packet can only be transmitted if there are enough tokens to cover its length in bytes.

• LB sends packets at an average rate. TB allows for large bursts to be sent faster by speeding up the output.

• TB allows saving up tokens (permissions) to send large bursts. LB does not allow saving.

Multiple chained buckets

Carrier Ethernet

• A ubiquitous, standardized, carrier-class Service and Network defined by five attributes that distinguish it from familiar LAN based Ethernet

Carrier Ethernet

Bandwidth profiles and traffic management

Bandwidth Profiles per EVC & per Class of Service Governed by 6 Parameters– CIR (Committed Information Rate)

• CIR defines assured bandwidth• Assured via bandwidth reservation, traffic engineering

– EIR (Excess Information Rate)• EIR bandwidth is considered ‘excess’• EIR improves the network’s Goodput • Traffic dropped at congestion points in the network

– CBS/EBS (Committed/Excess Burst Size in bytes)• Higher burst size results in improved performance

Color Mode (“Color Aware” or “Color Blind”) – When set as “Color Aware” governs discard eligibility

• Marking typically done at ingress• Green – Forwarded frames – CIR conforming traffic• Yellow – Discard Eligible frames – Over CIR , within EIR• Red – Discarded frames – Exceeds EIR

Coupling Flag (set to 1 or 0) governs which frames are classed as yellow

EVC-1 EVC-2

EVC-3

EIR

CE Bandwidth Profiles• Bandwidth Profiles can divide bandwidth per EVC over a single UNI

– Multiple services over same port (UNI)

– CoS markings enable the network to determine the network QoS to provide

UNI

EVC1

EVC2

EVC3

Ingress Bandwidth Profile Per Ingress UNI

Port-based

UNI

EVC1

EVC2

EVC3

Ingress Bandwidth Profile Per EVC1



Port/VLAN-based

UNI EVC1

CE-VLAN CoS 6 Ingress Bandwidth Profile Per CoS ID 6

CE-VLAN CoS 4

CE-VLAN CoS 2

Ingress Bandwidth Profile Per CoS ID 4

Ingress Bandwidth Profile Per CoS ID 2

EVC2

Port/VLAN/CoS-based

Carrier Ethernet in Action

Application EVPL Profiles, Sample CoS ObjectivesCarrier Ethernet Service Provider

Committed Information

RatePriority

Excess Information

Rate

10 mbps0 0

100 mbps1 0

50 mbps2 0

40 mbps3 0

04 500 mbps

Metro Fiber Ethernet Virtual Private Line Services

VoIP calls

Interactive business and consumervideo programming

Telepresence

Streamed HD live content

Content distributed. Development and non-real time delivery

UNICOMPANY HQ

Frame Delay

5ms

5ms

25ms

N/A

N/A

Frame Loss Ratio

0.1%

0.01%

0.1%

0.01%

1%

Implementation Guidance• The above bandwidth profiles and related Performance metrics are a small set of those available. • New MEF Specifications recommend performance objectives based on both distance and application types

Impact for Providers and Enterprises• Ability to tune Carrier Ethernet services to exactly match wide variety of changing applications requirements

creates a highly responsive network that reacts well to bursts of high priority data.

bandwidth management and qos

Engineering