Videoconference Quality of Service. Liane Tarouco Leandro Bertholdo

Transcription

1 Videoconference Quality of Service Liane Tarouco Leandro Bertholdo Providing QoS Client (University) - UFRGS Transit (state network) TCHE Transit (national network) - RNP 1

2 TCHÊ - Videoconference TCHÊ - Videoconference Problems Packet dropping high (> 30%) Traffic burst impact video transmission even when normal bandwidth usage was not too high 2

3 Tchê Used router implementation of DiffServ together with RSVP LLQ used to keep compatibility with Cisco Defined a service called HVIDEO (Expedited Forwarding) for video originated in the MCU and in the streaming video server Band reservation (19%) for HVIDEO Tchê Defined a service called CACHE (Assured Forwarding) for traffic using existing cache structure Band reservation (15%) for CACHE 3

4 Class of Services Models There are two levels where the quality of service 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 Level Agreement) Currently two models exist: IntServ DiffServ 4

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. IntServ: Integrated Services Three types of service are supported Best Effort Expedited Forwarding: For applications of real time, with controlled jitter and the conditional traffic for one token bucket. Assured Forwarding: For elastic applications. Is guaranteed the delivery of packages (low loss) and the retardation will not go to exceed the maximum retardation supported for the application 5

6 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. 6

7 DiffServ: Differentiated Services Defined for the IETF due the difficulty to implement the IntServ The packages are marked in accordance with the desired service A not configured node can harm but it does not to hinder the QoS DiffServ: Differentiated Services Two basic types of differentiated services exists: 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) 7

8 DiffServ: Differentiated Services How is implemented? RFC 2474 redefines the use of the field of ToS of the IPv4 Bits [345] Preference Bits [012] of Discarding Class of Service DiffServ: Differentiated Services Cisco Systems sugest the DSCP field Classe Precedence DSCP Classe DSCP Expedited Forwarding (EF) Assured Forwarding 4 (AF4) Assured Forwarding 3 (AF3) Assured Forwarding 2 (AF2) Assured Forwarding 1 (AF1) Best Effor (BE) 8

9 DiffServ: Differentiated Services A Cisco Systems recommends: Classe Assured Forwarding 3 (AF3) 2Premium 010(EF) is reserved Assured to real Forwarding time voice 2 (AF2) 1 0 Precedence DSCP Classe DSCP Expedited Forwarding (EF) The Remain is for user data Assured Forwarding 4 (AF4) AF41 is reserved to vídeo in videoconferences AF31 is reserved to voice control Assured Forwarding 1 (AF1) Best Effor (BE) AF13 is reserved to video streaming QoS in Internet One of the advantages of the DiffServ is that the customer can mark its DS-Field by yourself Polycom camera has this option It is not a good police The network team needs to validate the admission control process 9

10 QoS na Internet DiffServ expect that exists SLAs (Service Level 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 admission control is static in the edge router of the net. The intermediate nodes have the main five classes implemented Some equipments like MCUs has QoS control admission static configured Other videoconferences requests are configured as your needs. 10

11 Capacity Planning Before configuring it is necessary to guarantee 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 Transmission CODEC Minimum bandwidth to participate (conservative) Band= (Tx+ 0,2Tx) *3 56K 128K 256K 256 Kbps 512 Kbps 1 Mbps For a CODEC 512 (voice + video) 128Kbps 2 Mbps 1M Total Bandwidth = ( ,2*128 4 Mbps ) * 3 Total Bandwidth = (153,6) * 3 Total Bandwidth = 460,8 Kbps To reserve 153,6K (~160) it is necessary 460,8K (~512) *** Conservative *** 11

12 To validate QoS Rude/ Crude (traffic generator) /root]# cat /etc/rude.cfg START 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 = 300k ON :10001 CONSTANT OFF # Simulacao de Trafego H.323 # Trafego 42 x 33 = 110k ON :10001 CONSTANT OFF To validate QoS Beacon Server (sourceforge.net) Test Results Summary for Test ID: _ ====================================================== <<Test Session Information>> H.323 Beacon Client IP: H.323 Beacon Server IP: Test Session Date: 10/20/2005 Test Session Start Time: 12:50:22 Test Session End Time: 12:54:25 Duration of Test Session: 0:4:3 Codec used during Test Session: G.711-uLaw-64k{sw} Packets Sent during Test Session: 4896 Packets Received during Test Session: 4873 Octets Send during Test Session: Octets Received during Test Session:

13 Beacon Server/Client Beacon Server/Client 13

14 Beacon Server/Client QoS Configuration Examples CAR/DSCP access-list 191 permit udp host host ! int eth0/0 rate-limit input access-group conformaction set-dscp-transmit 46 exceed-action drop 14

15 QoS Configuration Examples LLQ policy-map llq class MCUs priority 96 class class-default fair-queue! interface Serial0/0 service-policy output llq RNP/GTRH COMDEX 15

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 16

17 SBRC2004 SBRC2004 access-list 180 permit ip any host access-list 180 permit ip any host access-list 180 permit ip host any access-list 180 permit ip host any! access-list 190 permit ip any host access-list 190 permit ip any host access-list 190 permit ip any host ! class-map match-all VOIP match access-group 180 class-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 17

18 SBRC2004 interface Serial2/0 description ====Circuito Gramado BRT Porta 7 - placa 4 ip load-sharing per-packet service-policy output SBRC! interface Serial2/1 description ====Circuito Gramado BRT Porta 8 - placa 4 ip load-sharing per-packet service-policy output SBRC SBRC2004 In this event some tools are used to validate an monitoring the QoS solution. Ethereal Netflow 18

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20 Conclusion To a good quality, Qos and bandwidth reservation is necessary, using VCs or RSVP The solution Diffserv & RSVP was completely aproved to VoIP and Videoconferences buffered or in real time. The RSVP has an inconvenient: you have to configure QoS in each link. New feature In Maio/2004 the Cisco launched version IOS 12.3(8) with feature auto-qos It allows recognition of applications through Cisco NBAR The politics of QoS can be defined through the Cisco Works. 20