quality of service in triple play

8/7/2019 quality of service in triple play

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Submitted By

Syndicate 1SITM 09


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` Telecom in converging

`Aim of service provider

o Deliver variety of services using same transfertechnology

o Minimize operation, administration andmanagement of equipments

` Customers requirement is quality of service


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QoS or Quality of service is the ability to

provide different priority to different applications,users, or data flows, or to guarantee a certain level

of performance to a data flow.


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Applications

Real-Time Elastic

Tolerent Intolerent


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Bandwidth oversubscription requires mechanisms to provide

contractually agreed bandwidth guarantees, as well as to ensure

that subscribers get at least a fair amount of the available

bandwidth.

Converged network infrastructure; voice and video traffic have

completely different requirements for jitter, delay and packet-loss

than data traffic and needs separate treatment.

Service providers want to offer differentiated traffic classes to gain

new revenue streams (e.g., business subscribers can be prioritized

over residential users and mission-critical applications over best-

effort data).


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` ITU regarded NGN as as a network with an end-to-end

service for voice, data and multimedia (triple play).

` All the services are based on the Internet Protocol (IP).

` Higher flexibility and simple integration of new applications


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Lat

Fix d D lay

Variabl d lay

Jitt r

Pack t Loss


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Packet Loss Rate

DelayUse of Soft Switch

Support IPv6


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VOICE


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Once a call has been accepted by call control and resources allocated to it the callshould be carried to completion with the required voice quality.

Established calls must be protected from network disturbances as far as physically

possible.

The network must be capable of supporting very high levels of call setup attempts.

In the event of focussed overload, calls that cannot be carried must be rejected

without degrading the call carrying capacity of the network.

Mechanisms must be available to ensure that emergency calls and high priority

calls receive preferential treatment

Call setup latency must be comparable to the existing network.

The network must be secure from denial of service attacks and spoofing

Some networks may require the support for call pre-emption.

QoS Requirements for VoIP


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Priority VoiceTraffic < 80 ms

Packet loss< 5% less < 35 ms Max 75%

IP CLASS OFSERVICE

ONE-WAYDELAY

THROUGHPUT JITTERQoS

BANDWIDTHPER AAPP

Real-Time Traffic Video

< 80 msPacket loss

< 3%60%

Priority DataTraffic

< 100 msPacket loss

< 2%30%

SLAs


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VoIP n/w architecture


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Customer Premises Equipment is deployed at the edge of the network equipmentmay be owned by the network operator but because it exists in insecure premises it

is not to be trusted.

The edge router acts as the boundary between networks. police incoming

customer flows and provide additional security mechanisms to prevent the misuse

of network resources by customers.

The call agent is located in the provider's network and provides call controlfunctions.

Network operators in general interconnect at the call control layer, in this case

each network

operator has at least one call agent and offers a call control interface over the

interconnect (e.g.

SIP). Multimedia terminals such as PCs or SIP phones connect directly to the IP network

without requiring media adaptation.

Features of architecture


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QoS Solutions for VoIP

Integrated Services (Intserv)

The integrated services, or Intserv, method of providing quality of service is to use a

protocol for explicitly reserving bandwidth on a per flow basis. This protocol is the

internet reservation protocol, or RSVP (the signalling mechanism)

When used as part of Intserv RSVP provides a method for a user to request aparticular quality of service for a session, in effect this reserves the bandwidth

throughout the network for the duration of the session

Although IP networks are connectionless networks, RSVP provides a mechanism to

ensure that the reservation message returns by the same route as the path

messages, although this route through the network may change over the duration of

a session

Once established an Intserv session must be maintained by each router along the

path of the session


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Differentiated Services (Diffserv)

The Diffserv approach to providing QoS support differs fundamentally from Intserv

in that it does not refer to a specific protocol for providing quality of service but

rather an architectural framework designed to facilitate QoS

The network is divided into one or more Diffserv domains.

Sources and sinks of traffic outside of the Diffserv domain are considered

customers andwould typically have an appropriate Service Level Specification that

defined how much traffic and of what type they could pass into, and receive from

the Diffserv domain. It is important tonote that these sources may not be individual

users but could be an entire network.

The edge of the diffserv domain is made up of Diffserv boundary routers. A

Diffserv boundary router performs traffic classification and traffic conditioning and

policing. It must provide functions for admission control, policy enforcement.


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Unlike Intserv, Diffserv QoS functions are not applied to a single flow from a

customer. Diffserv classifies traffic into a series of classes (otherwise known as per hop

behaviours) and applies the same treatment to all traffic within a class.

The core of a diffserv domain is made up of Diffserv core routers. Diffserv core

routers are intended to concentrate solely on traffic handling, processing each packet

based on how the packet was marked at the Diffserv Boundary. Handles traffic

according to priorities and service levels.

Use of bandwidth manager


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MPLS-TE

MPLS can be used inside a network to setup label switched paths between

ingress and egress points in the network, in effect this creates tunnels down

which appropriately tagged traffic flows.

By assigning a bandwidth to the label switched path on establishment it is

possible to ensure that traffic being carried over a label switched path is

guaranteed to be delivered to the egress point provided that the total traffic

admitted to the label switched path does not exceed the bandwidth allocated to

it.

Many individual flows can be carried without requiring the explicit reservation of

resources for each individual flow.

Aggregate reservation can be varied with time to allow for fluctuating traffic

flows in a network and when combined with MPLS fast re-routing it allows for a

resilient network to be created where even significant network failures have

very limited impact on the traffic being carried by a particular label switched

path.


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Access to the network is controlled by the call server which instructs the edge

router to permit individual flows.

The call server generates an authorisation token that is passed to the client. This

is used during the bearer setup in the access network to ensure that the flow has

been authorised by the call server.The edge router is responsible for policing an individual flow according to the

session information provided by the call server.

Traffic flows that have not been authorised by the call server will not be granted

resources by the edge router.

3GPP have defined a COPS interface between the call server and the edge

router.

3GPP require that the edge router support Diffserv boundary functions and

allow (but do not require) the use of RSVP for resource reservation.

3GPP support a two stage mechanism for resource reservation, a resource

authorisation phaseand a resource commit phase.

3GPP end-to-end QoS concept features


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Ensure Quality at All Phases of Triple-Play ServiceDeployments

Installation

Provisioning/activation

Service/troubleshooting

DATA

Supports the latest DSL standards

Terminate and Through mode operation IP layer testing: ping, trace route and Web download

speed


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Annex A option (over POTS):ITU-T G.992.5 (ADSL2+), ITU-T G.992.3 (ADSL2 andRE-ADSL2), ITU-T G.992.1 (G.DMT) and ANSI T1.413Issue 2

Annex B option (over ISDN):ITU-T G.992.5 (ADSL2+), ITU-T G.992.3 (ADSL2 andRE-ADSL2), ITU-T G.992.1 (G.DMT)

` Rates supported Downstream: up to 24 Mb/s

` Upstream: up to 1 Mb/s


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Measurements Maximum bit rates (upstream and downstream) Actual bit rates Mode: Fast, Interleaved Capacity Output power Carrier load (Bits/Bin)

Signal-to-noise ratio (SNR) margin Transmit (Tx) power Attenuation Receiver (Rx) gain EOC channel information


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` ADSL, ATM, IP layer analysis

` Bandwidth usage per channel

` IGMP packets

` Set-top box (STB) traffic

` Key IP video QoS parameters

` Packet loss, packet jitter, zap time

` QoS pass/fail indicators


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` IPLR-IP Packet Loss Ratio

` IPTD-IP Packet Transfer Delay

` IPDV-IP Packet Delay Variation (Jitter)

` IPER-IP Packet Error Ratio.


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IMPLEMENTATIONOF QoS


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OBSTACLES TOCOMMUNICATION

DelayDefines the latency that occurs when traffic is sent end-to-

end across a network.

JitterDescribes the fragmentation that occurs when traffic arrives

at irregular times or in the wrong order.

Data LossDefines the packet loss that occurs due to link congestion.


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METHODOLGYFORIMPLEMENTING QoS

BEST EFFORT QoS Is essentially no QoS

Traffic is routed on first come first serve basis

Best Effort is the default behavior of routers and switches

Is easy to implement and is highly scalable

Internet forwards traffic on a Best Effort basis

INTEGRATED SERVICE QoS (IntServ) Also known as end-to-end or Hard QoS

IntServ QoS requires an application to signal

An Admission Control protocol allocates resources end-to-endfor the application

If resources cannot be allocated, the request is denied

Is not considered to be a scalable option

Example of IntServ is Resource ReserVation Protocol (RSVP)


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DIFFERENTIATED SERVICE QoS (DiffServ) Is designed to be a scalable QoS solution

Traffic types are organized into specific classes

And than marked to identify their classification

Policies are then created on a per hop basis to provide aspecific level of service

Is scalable and flexible in enterprise environment

Considered to be soft QoS, as it does not absolutely guarantee

service

METHODOLOGY (cont.)


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QoS TOOLS

Classification and Marking Queuing

Queue congestion avoidance

First-In First-Out (FIFO)

Priority Queuing (PQ)

Custom Queuing (CQ)

Weighted Fair Queuing (WFQ) Class-Based Weighted Fair Queuing (CBWFQ)

Low-Latency Queuing (LLQ)

QUEUING

MECHANI

SM


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quality of service in triple play

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