Chapter 8: Configuring Your 2600, 3600, or AS5300 for Voice over IP 8-1 Copyright © 1998, Cisco Systems, Inc.

8-2CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Given the need to transport VoIP, identify the issues that must be addressed to transport delay sensitive traffic like voice over an IP network Given an existing data network, configure the host and WAN with RSVP, weighted fair queuing, and RTP header compression to carry real-time traffic Given a VoIP network, improve voice quality by setting the quality of service options on the VoIP dial peers Given a VoIP network and verification commands, verify the configurations necessary for a VoIP call Objectives Upon completion of this chapter, you will be able to perform the following tasks:

Introduction 8-3 Copyright © 1998, Cisco Systems, Inc.

IP Networks Overview 8-4 Copyright © 1998, Cisco Systems, Inc.

8-5CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. IP Networks Overview IP assumes delay and packet ordering problems

Voice over IP Protocols 8-6 Copyright © 1998, Cisco Systems, Inc.

8-7CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. PresentationSessionTransportNetworkLinkPhysicalG.729/G.711H.323/H.323Gateway/SIP/SDPRTP/UDP/RSVPIP/WFQ/IP-prec MLPPP/FR/ATM AAL1 – – – Voice over IP Protocol Stack

8-8CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Signaling from PBX to Router Internet PBX Trunk Signaling The PBX seizes a trunk line to the router, and forwards dial digits

8-9CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Signaling between Routers H.323 Agent Internet PBX Q.931 The Dial Plan Mapper reads the dial digits, and finds the address of the remote IP peer. The H.323 agent initiates a Q.931 call to the remote peer.

8-10CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Trunk Signaling PBX H.323 Agent Internet Q.931 The remote H.323 agent seizes a PBX trunk, returns a Q.931 acknowledgment to the origin, and forwards dial digits to the PBX Signaling from Router to PBX

Configuring Network for Voice Traffic 8-11 Copyright © 1998, Cisco Systems, Inc.

8-12CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. RTP and RTCP Real-Time Transfer Protocol Connectionless environment Payload type identification, sequence numbering Time-stamping, delivery monitoring Real-Time Transfer Control Protocol Provides feedback on current network conditions

8-13CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. RTP Header Compression Before RTP Header Compression After RTP Header Compression IPRTPUDPPayload Header 40 bytes PayloadHeader 20 bytes8 bytes12 bytes bytes 2 or 4 bytes bytes RTP header compression saves bandwidth by compressing packet headers

8-14CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Configuring RTP Header Compression Router(config-if)# ip rtp header-compression [ passive ] Compresses header from 40 bytes to 2 or 4 most of the time Router(config-if)# ip rtp compression connections number Specifies the total number of RTP header compression connections supported on an interface

8-15CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Configuring QoS and RSVP Router(config-if)# ip rsvp bandwidth [ interface-kbps ][ single-flow-kbps ] Allows you to reserve bandwidth for real-time traffic Provides the policy to weighted fair queuing

8-16CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Configuring Weighted Fair Queuing Router(config-if)# fair-queue [ congestive-discard-threshold [ dynamic-queues [ reservable-queues ]]] Queuing algorithm to sort traffic Works well with RSVP Schedules interactive traffic like voice to the front and shares remaining bandwidth for other traffic

WAN Interface Options 8-17 Copyright © 1998, Cisco Systems, Inc.

8-18CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Frame Relay OptionAdditional Configurations for Voice Router(config)# interface interface number Enters interface or subinterface configuration mode Router(config-if)# encapsulation frame-relay Enables Frame Relay on the interface Router(config-if)# frame-relay interface-dlci dlci Assigns a DLCI to a Frame Relay subinterface

8-19CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. 640 * 320 * 640 * Frame Serialization Delay Matrix Frame Size 56 kbps * 9 ms 18 ms 36 ms 72 ms 144 ms 214 ms 1 1 Byte 64 Bytes 128 Bytes 256 Bytes 512 Bytes 1024 Bytes 1500 Bytes 64 kbps 125 * 8 ms 125 * 16 ms 32 ms 64 ms 128 ms 187 ms 128 kbps 62.5 * 4 ms 8 ms 16 ms 32 ms 64 ms 93 ms 256 kbps 31 * 2 ms 4 ms 8 ms 16 ms 32 ms 46 ms 512 kbps 15.5 * 1 ms 2 ms 4 ms 8 ms 16 ms 23 ms 768 kbps 10 * 640 * 10 * 1.3 ms 2.6 ms 5.1 ms 10.2 ms 15 ms 1536 kbps 5 *320 * 640 * 5 * 1.3 ms 2.6 ms 5.1 ms 2.6 ms 7.5 ms Link Speed * Size in microseconds 5.1 ms

8-20CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Configuring MTU Router(config-if)# mtu bytes Specifies the maximum packet size a particular interface can transmit Lowering the MTU size will allow larger data packets to interleave with voice packets

8-21CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Configuring Generic Traffic Shaping Router(config-if)# traffic-shape rate bit-rate [ burst-size [ excess-burst-size ]] Enables traffic shaping for outbound traffic on an interface Limits chances for voice packets to be discarded

8-22CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Configuring Frame Relay WAN Interface Example R1 IP Cloud (408) (408) 527-… /16 Voice Port 1/0/0 S0/0 Enables Frame Relay on the interface. Sets an MTU to 300, a low packet size. Enables RTP header compression on the interface. Enables weighted fair queuing. Interface configuration on R1 (voip1): voip1# interface serial0/0 voip1(config-if)#no ip address voip1(config-if)#encapsulation frame-relay voip1(config-if)#mtu 300 voip1(config-if)#frame-relay ip rtp header-compression voip1(config-if)#fair-queue Do not configure the address on the primary interface.

8-23CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Configuring Frame Relay WAN Subinterface Example R1 IP Cloud R2 (408) (408) 527-… Voice Port 1/0/0 S0/0.1 Enables RSVP and reserves 48 kbps (75 percent) of bandwidth. Sets bandwidth to 64 kbps. Enables RTP header compression on subinterface. Subinterface configurations made to R1 (voip1): voip1(config-subif)#interface serial0/0.1 point-to-point voip1(config-subif)#bandwidth 64 voip1(config-subif)#ip rsvp bandwidth voip1(config-subif)#traffic-shape rate voip1(config-subif)#frame-relay interface-dlci 16 voip1(config-subif)#frame-relay ip rtp header-compression Enables generic traffic shaping.

8-24CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. PPP Option Configuring Multiclass Multilink PPP for Voice Router(config-if)# ppp multlink Enables Multilink PPP Router(config-if)# ppp multilink interleave Enables real-time packet interleaving

8-25CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. interface virtual-template 1 ip address no ip mroute-cache ppp multilink ppp multilink interleave multilink virtual-template 1 Configuring Multiclass Multilink PPP for Voice Example

Configuring RSVP, IP Precedence, Codec and VAD on VoIP Dial Peers 8-26 Copyright © 1998, Cisco Systems, Inc.

8-27CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Configuring RSVP Router(config-dial-peer)# acc-qos { best-effort | controlled load | guaranteed-delay } Requests an SNMP event if QoS falls below a specified level Router(config-dial-peer)# req-qos { best-effort | controlled load | guaranteed-delay } Specifies the desired QoS on the VoIP dial peer

8-28CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Router(config-dial-peer)# ip precedence number Specifies the IP precedence, priority, value Configuring IP Precedence

8-29CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Configuring Codec and VAD Router(config-dial-peer)# codec { g711alaw | g711ulaw | g729r8 } Specifies the voice coder rate of speech for a VoIP dial peer Router(config-dial-peer)# vad Enables VAD

8-30CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. show dial-peer voice Output on VoIP Dial Peer VoiceOverIpPeer110 tag = 110, destination-pattern = ` ', answer-address = `', group = 110, Admin state is up, Operation state is up type = voip, session-target = `ipv4: ', ip precedence: 0 UDP checksum = disabled session-protocol = cisco, req-qos = guaranteed, acc-qos = guaranteed, fax-rate = voice, codec = g729r8, Expect factor = 10, Icpif = 30, VAD = enabled, Poor QOV Trap = disabled Connect Time = 44739, Charged Units = 0 Successful Calls = 35, Failed Calls = 0 Accepted Calls = 35, Refused Calls = 0 Last Disconnect Cause is "10 " Last Disconnect Text is "normal call clearing." Last Setup Time =

Configuring Number Expansion 8-31 Copyright © 1998, Cisco Systems, Inc.

8-32CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Configuring Number Expansion Router(config)# num-exp extension-number expanded-number Allows you to dial an extension only on a PBX

Lab Exercise 8-33 Copyright © 1998, Cisco Systems, Inc.

8-34CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Lab Setup /24 IP Cloud /24 voip10voip11 S0/0 FXS 1/0/0 FXS 1/0/ FXS 1/0/0 FXS 1/0/1

8-35CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. VoIP Lab Configuration /24 voip10 S0/0 FXS 1/0/0 FXS 1/0/ /24 voip11 S0/ FXS 1/0/0 FXS 1/0/ /24 voip12 S0/0 FXS 1/0/0 FXS 1/0/ /24 voip14 S0/0 FXS 1/0/0 FXS 1/0/ /24 voip16 S0/0 FXS 1/0/0 FXS 1/0/ /24 voip17 S0/ FXS 1/0/0 FXS 1/0/ /24 voip15 S0/ FXS 1/0/0 FXS 1/0/ /24 voip13 S0/ FXS 1/0/0 FXS 1/0/1 IP Cloud (Frame Relay Switch) S0 S2 S6 S4 S1 S7 S5 S3

8-36CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc.

8-37CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc.

8-38CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc.

8-39CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc.

8-40CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc.

8-41CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc.

8-42CVOICEConfiguring Your 2600, 3600, or AS5300 for Voice over IP Copyright © 1998, Cisco Systems, Inc. Identify the issues that must be addressed to transport delay sensitive traffic like voice over an IP network Configure the host and WAN with RSVP, weighted fair queuing, and RTP header compression to carry real-time traffic like voice Improve voice quality by setting the quality of service options on the VoIP dial peers Verify the configurations necessary for a VoIP call Summary In this chapter you learned how to complete the following tasks: