Post on 22-Nov-2018
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VideoconferenceQuality of Service
Liane TaroucoLeandro Bertholdo
Providing QoS
� Client (University) - UFRGS� Transit (state network) – TCHE� Transit (national network) - RNP
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TCHÊ - Videoconference
TCHÊ - Videoconference
� Problems– Packet dropping high (> 30%)– Traffic burst impact video transmission
even when normal bandwidth usage wasnot too high
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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
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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
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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.
IntServ: Integrated Services
� 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
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IntServ: Integrated Services� It use messages PATH / RESV� The application define
• Bandwidth• Time to use the resource• Maximum bandwidth traffic burst
IntServ: Integrated Services
� 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.
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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
DiffServ: Differentiated Services
� 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)
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DiffServ: Differentiated Services
� 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
DiffServ: Differentiated Services
� Cisco Systems™ sugest the DSCP field
Best Effor (BE)0000000000
Assured Forwarding 1 (AF1)0010000011
Assured Forwarding 2 (AF2)0100000102
Assured Forwarding 3 (AF3)0110000113
Assured Forwarding 4 (AF4)1000001004
Expedited Forwarding (EF)1010001015
Classe DSCPDSCPPrecedenceClasse
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DiffServ: Differentiated Services
� A Cisco Systems™ recommends:
Best Effor (BE)0000000000
Assured Forwarding 1 (AF1)0010000011
Assured Forwarding 2 (AF2)0100000102
Assured Forwarding 3 (AF3)0110000113
Assured Forwarding 4 (AF4)1000001004
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
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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.
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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 ***
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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
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Beacon Server/Client
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
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QoS Configuration Examples
� LLQ
policy-map llq class MCUspriority 96
class class-defaultfair-queue
!interface Serial0/0
service-policy output llq
RNP/GTRHCOMDEX
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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
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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
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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
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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