Configuring campus switches to support voice
Sponsored Links
This presentation is the property of its rightful owner.
1 / 27

Configuring Campus Switches to Support Voice PowerPoint PPT Presentation


  • 100 Views
  • Uploaded on
  • Presentation posted in: General

Configuring Campus Switches to Support Voice. BCMSN Module 7 Lesson 1. Objectives. Explain why an organization would want to run VoIP on the network Describe the main components of a VoIP network, including IP-enabled PBX, user end-devices, gateways and gatekeepers, and the IP network

Download Presentation

Configuring Campus Switches to Support Voice

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Configuring Campus Switches to Support Voice

BCMSN Module 7 Lesson 1


Objectives

  • Explain why an organization would want to run VoIP on the network

  • Describe the main components of a VoIP network, including IP-enabled PBX, user end-devices, gateways and gatekeepers, and the IP network

  • Compare the uniform bandwidth consumption of voice traffic to the intermittent bandwidth consumption of data traffic

  • Describe a VoIP call flow through a network and where contention for bandwidth between data traffic and voice traffic will occur

  • Explain an auxiliary VLAN

  • Identify a solution for latency, jitter, bandwidth, packet loss, reliability, and security

  • Explain the importance of high availability in the campus network to support a VoIP implementation

  • Explain the use of AutoQoS in Cisco Catalyst switches

  • Describe the commands that enable AutoQoS on Cisco Catalyst switches


Purpose of this Lesson

  • Coverage of topics new to the “Configuring Campus Switches to Support Voice and Video Applications” module of BCMSN.

  • What’s new in this module?

    • More information about Converged Networks.

    • Updated content for VoIP components and functionality.

    • Description of traffic types and call flow for VoIP.

    • New auto qos commands for voice.

    • Overall content is updated and reorganized.

  • This lesson does not cover QoS. The QoS module of BCMSN is largely unchanged.


The Basics

  • VoIP is a technology that digitizes sound, divides that sound into packets, and transmits those packets over an IP network.

  • VoIP evolved into IP telephony, delivering packetization to the desktop through IP phones. IP telephony uses telephone-like handsets, and users dial regular telephone numbers.

  • IP Communications, also called unified communications or converged communications, is the next stage in the evolution. Tying together telephone, voice mail, e-mail, and information services, via familiar-looking telephone equipment.


Benefits of a Converged Network

  • More efficient use of bandwidth and equipment

  • Lower transmission costs

  • Consolidated network expenses

  • Increased revenue from new services

  • Service innovation

  • Access to new communications devices

  • Flexible new pricing structures


VoIP Network Components


VoIP Call Flow


Codecs

  • A codec (Coder/Decoder) converts analog signals to a digital bitstream, and another identical codec at the far end of the communication converts the digital bitstream back into an analog signal.

  • Codecs generally provide a compression capability to save network bandwidth.


Auxiliary VLANs


Self Check

  • What is a codec used for in VoIP?

  • Which VoIP component provides translation between VoIP and non-VoIP networks?

  • What is call control signaling?

  • What protocol is used to carry actual voice samples?

  • What is the auxiliary VLAN feature supported by some Catalyst switches?


QoS


Converged Networks Require QoS

  • Traditional telephony networks reserve resources and guarantee voice quality.

  • Traditional data networks are best effort, with no guarantee of delivery, delay or timing. Depend on TCP upper-layer protocols for reliability.

  • Converged networks must use QoS to ensure that voice and data can be supported on the same network.


Characteristics of Voice and Data


One-Way

Requirements

Voice QoS RequirementsProvisioning for Voice

Voice

  • Latency ≤ 150 ms

  • Jitter ≤ 30 ms

  • Loss ≤ 1%

  • 17–106 kbps guaranteed priority bandwidth per call

  • 150 bps (+ layer 2 overhead) guaranteed bandwidth forvoice-control traffic per call

  • CAC (call admission control) must be enabled

  • Smooth

  • Benign

  • Drop sensitive

  • Delay sensitive

  • UDP priority


QoS Basics


AutoQoS

One command per interface to enable and configure QoS.


AutoQoS Benefits

  • Application Classification

  • Policy Generation

  • Configuration

  • Monitoring and Reporting

  • Consistency


Configuring AutoQoS

  • Single command at the interface level configures interface and global QoS.

  • Supported on static, dynamic-access, voice VLAN access, and trunk ports.

  • CDP must be enabled for AutoQoS to function properly.


!

mls qos map cos-dscp 0 8 16 26 32 46 48 56

mls qos srr-queue output cos-map queue 1 threshold 3 5

mls qos srr-queue output cos-map queue 2 threshold 3 3 6 7

mls qos srr-queue output cos-map queue 3 threshold 3 2 4

mls qos srr-queue output cos-map queue 4 threshold 2 1

mls qos srr-queue output cos-map queue 4 threshold 3 0

mls qos srr-queue output dscp-map queue 1 threshold 3 40 41 42 43 44 45 46 47

mls qos srr-queue output dscp-map queue 2 threshold 3 24 25 26 27 28 29 30 31

mls qos srr-queue output dscp-map queue 2 threshold 3 48 49 50 51 52 53 54 55

mls qos srr-queue output dscp-map queue 2 threshold 3 56 57 58 59 60 61 62 63

mls qos srr-queue output dscp-map queue 3 threshold 3 16 17 18 19 20 21 22 23

mls qos srr-queue output dscp-map queue 3 threshold 3 32 33 34 35 36 37 38 39

mls qos srr-queue output dscp-map queue 4 threshold 1 8

mls qos srr-queue output dscp-map queue 4 threshold 2 9 10 11 12 13 14 15

mls qos srr-queue output dscp-map queue 4 threshold 3 0 1 2 3 4 5 6 7

mls qos queue-set output 1 threshold 1 138 138 92 138

mls qos queue-set output 1 threshold 2 138 138 92 400

mls qos queue-set output 1 threshold 3 36 77 100 318

mls qos queue-set output 1 threshold 4 20 50 67 400

mls qos queue-set output 2 threshold 1 149 149 100 149

mls qos queue-set output 2 threshold 2 118 118 100 235

mls qos queue-set output 2 threshold 3 41 68 100 272

mls qos queue-set output 2 threshold 4 42 72 100 242

mls qos queue-set output 1 buffers 10 10 26 54

mls qos queue-set output 2 buffers 16 6 17 61

mls qos

!

!

interface GigabitEthernet0/1

srr-queue bandwidth share 10 10 60 20

srr-queue bandwidth shape 10 0 0 0

queue-set 2

mls qos trust device cisco-phone

mls qos trust cos

auto qos voip cisco-phone

!

AutoQoS VoIP for Catalyst Switches

CAT2970(config-if)#auto qos voip cisco-phone


!

class-map match-any AutoQoS-VoIP-RTP-Trust

match ip dscp ef

class-map match-any AutoQoS-VoIP-Control-Trust

match ip dscp cs3

match ip dscp af31

!

!

policy-map AutoQoS-Policy-Trust

class AutoQoS-VoIP-RTP-Trust

priority percent 70

class AutoQoS-VoIP-Control-Trust

bandwidth percent 5

class class-default

fair-queue

!

!

interface Multilink2001100117

bandwidth 768

ip address 10.1.102.2 255.255.255.0

service-policy output AutoQoS-Policy-Trust

ip tcp header-compression iphc-format

no cdp enable

ppp multilink

ppp multilink fragment delay 10

ppp multilink interleave

ppp multilink group 2001100117

ip rtp header-compression iphc-format

!

!

interface Serial2/0

bandwidth 768

no ip address

encapsulation ppp

auto qos voip trust

no fair-queue

ppp multilink

ppp multilink group 2001100117

!

AutoQoS VoIP: WAN

interface Serial2/0

bandwidth 768

ip address 10.1.102.2 255.255.255.0

encapsulation ppp

auto qos voip trust


Configuring AutoQoS: Native OS

Switch(config-if)#

auto qos voip trust

  • The uplink interface is connected to a trusted switch or router, and the VoIP classification in the ingress packet is trusted.

Switch(config-if)#

auto qos voip cisco-phone

  • Automatically enables the trusted boundary feature, which uses the CDP to detect the presence or absence of a Cisco IP Phone.

  • If the interface is connected to a Cisco IP Phone, the QoS labels of incoming packets are trusted only when the Cisco IP Phone is detected.


Monitoring AutoQoS

Switch#

show auto qos [interface interface-id]

  • Displays the AutoQoS configuration that was initially applied

  • Does not display any user changes to the configuration that might be in effect

Switch#show auto qos

Initial configuration applied by AutoQoS:

wrr-queue bandwidth 20 1 80 0

no wrr-queue cos-map

wrr-queue cos 1 0 1 2 4

wrr-queue cos 3 3 6 7

wrr-queue cos 4 5

mls qos map cos-dscp 0 8 16 26 32 46 48 56

!

interface FastEthernet0/3

mls qos trust device cisco-phone

mls qos trust cos


Self Check

  • Describe the characteristics of a traditional data network.

  • Describe the QoS requirements of voice traffic.

  • What 3 QoS quality factors directory affect voice quality?

  • What is the Cisco Auto QoS feature?

  • What Cisco protocol must be enabled for AutoQoS to function properly?


Summary

  • Converged networks reduce costs and increase productivity.

  • VoIP equipment consists of a VoIP phone and a network infrastructure capable of supporting VoIP.

  • Auxiliary VLANs provide the ability to apply QoS to voice traffic without affecting the flow of data from the client PC.

  • To ensure high quality VoIP, implementation of QoS is required.

  • AutoQoS is a simple way to implement a trust boundary for VoIP.


Q and A


Resources

  • FCC VoIP Frequently Asked Questions

    • http://www.fcc.gov/voip/

  • VoIP Provider Information

    • http://voipreview.org/faq.aspx

  • Cisco Press Book:

    • “Internet Phone Services Simplified”, by Jim Doherty, Neil Anderson, 2006.


  • Login