providing qos - universidade federal do rio grande do...

1

VideoconferenceQuality of Service

Liane TaroucoLeandro Bertholdo

Providing QoS

� Client (University) - UFRGS� Transit (state network) – TCHE� Transit (national network) - RNP

2

TCHÊ - Videoconference

TCHÊ - Videoconference

� Problems– Packet dropping high (> 30%)– Traffic burst impact video transmission

even when normal bandwidth usage wasnot too high

3

Tchê

� Used router implementationof DiffServ together with RSVP

� LLQ used to keep compatibility with Cisco� Defined a service called HVIDEO

(Expedited Forwarding) for videooriginated in the MCU and in thestreaming video server– Band reservation (19%) for HVIDEO

Tchê

� Defined a service called CACHE (AssuredForwarding) for traffic using existingcache structure– Band reservation (15%) for CACHE

4

Class of Services Models

� There are two levels where the quality ofservice can be implemented:

– Applications• Are reactive• they use of buffers of application• Negotiation between transmitter and receiver

– Network

Class of Services Models

� Network QoS– Use of the intermediate nodes to privilege

packages of an application– For wide scale networks is necessary the

definition of SLAs (Service LevelAgreement)

– Currently two models exist:• IntServ• DiffServ

5

IntServ: Integrated Services

� Recommended by ITU98 (H.323)� Characterized for the reserve of resources� Use RSVP (Resource Reservation Protocol)� The application needs to configure the path

and the reserve of resources.


� Three types of service are supported– Best Effort– Expedited Forwarding: For applications of

real time, with controlled jitter and theconditional traffic for one token bucket.

– Assured Forwarding: For elasticapplications. Is guaranteed the delivery ofpackages (low loss) and the retardation willnot go to exceed the maximum retardationsupported for the application

6

IntServ: Integrated Services� It use messages PATH / RESV� The application define

• Bandwidth• Time to use the resource• Maximum bandwidth traffic burst


� There are several problems to use:– The authentication of the solicitation– All the intermediate routers need to

understand (PATH/RSVP) messages– Do not scale well:

• Flow status need to be maintained• It can not have enough bandwidth in you link

– Does not possible in Internet today.

7

DiffServ: Differentiated Services

� Defined for the IETF due the difficulty toimplement the IntServ

� The packages are marked in accordance withthe desired service

� A not configured node can harm but it doesnot to hinder the QoS


� Two basic types of differentiated servicesexists:– Express Forwarding

• Needs low delay e jitter

• Adjusted for applications that use Voice over IP(G.7xx).

– Assured Forwarding• They need a band guarantee• Jitter and delay can be treated by the

application• Good for video and control (H.263,H.245 e T.120)

8


� How is implemented?– RFC 2474 redefines the use of the field of ToS

of the IPv4

Bits [012]Class of Service

Bits [345]Preference of Discarding


� Cisco Systems™ sugest the DSCP field

Best Effor (BE)0000000000

Assured Forwarding 1 (AF1)0010000011




Expedited Forwarding (EF)1010001015

Classe DSCPDSCPPrecedenceClasse

9


� A Cisco Systems™ recommends:

Best Effor (BE)0000000000





Expedited Forwarding (EF)1010001015

Classe DSCPDSCPPrecedenceClasse

The Remain is for user data

Premium (EF) is reserved to real time voiceAF41 is reserved to vídeo in videoconferencesAF31 is reserved to voice control

AF13 is reserved to video streaming

QoS in Internet

� One of the advantages of the DiffServ is thatthe customer can mark its DS-Field byyourself– Polycom camera has this option– It is not a good police– The network team needs to validate the

admission control process

10

QoS na Internet

� DiffServ expect that exists SLAs (ServiceLevel Agreements)

� SLA defines:– Types of services supported– Static or– Dynamic (BB – Bandwidht Broker)

QoS na Rede Tchê e RNP

� In the Tchê network and RNP the admissioncontrol is static in the edge router of the net.

� The intermediate nodes have the main fiveclasses implemented

� Some equipments like MCUs has QoScontrol admission static configured

� Other videoconferences requests areconfigured as your needs.

11

Capacity Planning

� Before configuring it is necessary toguarantee band for all the applications

� Cisco™ recommends– all reserves can not be over 75% of the

total band– Voice applications can be over 1/3 (33%)

of the total bandwidth– It have to make planning of 20% over of

the real bandwidth conference

Planejamento de Capacidade

4 Mbps1M

2 Mbps512

1 Mbps256K

512 Kbps128K

256 Kbps56K

Minimum bandwidth to participate(conservative) Band= (Tx+ 0,2Tx) *3

TransmissionCODEC

For a CODEC (voice + video) 128KbpsTotal Bandwidth = (128 + 0,2*128 ) * 3

Total Bandwidth = (153,6) * 3Total Bandwidth = 460,8 Kbps

To reserve 153,6K (~160) it is necessary 460,8K (~512)*** Conservative ***

12

To validate QoS

� Rude/ Crude (traffic generator)[root@mcu /root]# cat /etc/rude.cfgSTART NOW# <stime> <id> ON <sport> <dst.add>:<dst.port> <type> [type parameters]# CONSTANT nro_pacotes tam_bytes# Simulacao de Trafego T.120# Trafego 25 x 1500 x 8 = 300k1000 0020 ON 1503 200.238.20.69:10001 CONSTANT 24 150060000 0020 OFF# Simulacao de Trafego H.323# Trafego 42 x 33 = 110k1000 0030 ON 3002 200.238.20.69:10001 CONSTANT 42 33060000 0030 OFF

To validate QoS

� Beacon Server (sourceforge.net)

Test Results Summary for Test ID: 20051020_125425======================================================

<<Test Session Information>>H.323 Beacon Client IP: 150.188.17.151H.323 Beacon Server IP: 200.132.0.100Test Session Date: 10/20/2005Test Session Start Time: 12:50:22Test Session End Time: 12:54:25Duration of Test Session: 0:4:3Codec used during Test Session: G.711-uLaw-64k{sw}Packets Sent during Test Session: 4896Packets Received during Test Session: 4873Octets Send during Test Session: 1175040Octets Received during Test Session: 1169520

13

Beacon Server/Client


14


QoS Configuration Examples

� CAR/DSCP

access-list 191 permit udp host 200.132.0.119 host 200.238.20.69!int eth0/0

rate-limit input access-group 191 128000 128000 128000 conform-action set-dscp-transmit 46 exceed-action drop

15

QoS Configuration Examples

� LLQ

policy-map llq class MCUspriority 96

class class-defaultfair-queue

!interface Serial0/0

service-policy output llq

RNP/GTRHCOMDEX

16

COMDEX

� Solution: DiffServ + RSVP� Patronization needed in PPP links and ATM

networks� Hotel Meliá->PoP-RS/RNP: LLQ in cisco� PoP-RS -> Interior: LLQ in IBM routers

Configuração do QoS

� Queue Strategy: LLQ(Low Latency Queuing� Type of service: EF (Expedited Forwarding)� Reservation: Variable, set one by one in each

link

17

SBRC2004

SBRC2004access-list 180 permit ip any host 200.132.16.32access-list 180 permit ip any host 200.132.16.33access-list 180 permit ip host 200.128.80.175 anyaccess-list 180 permit ip host 200.135.0.8 any!access-list 190 permit ip any host 200.132.16.64access-list 190 permit ip any host 200.132.16.65access-list 190 permit ip any host 200.132.16.66!class-map match-all VOIP match access-group 180class-map match-all VIDEO match access-group 190!policy-map SBRC class VOIP priority 800 class VIDEO bandwidth 700 class class-default fair-queue

IP Phones

Video Stream

18

SBRC2004interface Serial2/0 description ====Circuito Gramado BRT 0460702 -

Porta 7 - placa 4ip load-sharing per-packetservice-policy output SBRC !interface Serial2/1 description ====Circuito Gramado BRT 0460703 -

Porta 8 - placa 4ip load-sharing per-packetservice-policy output SBRC

SBRC2004� In this event some tools are used to validate

an monitoring the QoS solution.– Ethereal– Netflow

20

Conclusion

� To a good quality, Qos and bandwidth reservation isnecessary, using VCs or RSVP

� The solution Diffserv & RSVP was completelyaproved to VoIP and Videoconferences buffered or inreal time.

� The RSVP has an inconvenient: you have toconfigure QoS in each link.

New feature

� In Maio/2004 the Cisco launched version IOS12.3(8) with feature auto-qos

� It allows recognition of applications throughCisco NBAR

� The politics of QoS can be defined throughthe Cisco Works.

� www.cisco.com/go/qos

providing qos - universidade federal do rio grande do...

Documents