Cisco VoIP CME QoS Labs by Michael T. Durham Welcome to NetCertLabs CCNA Voice Lab series. In this set of labs we will be working with the QoS (Quality of Service). A communications network forms the backbone of any successful organization. These networks transport a multitude of applications and data, including high-quality video and delay-sensitive data such as real-time voice. The bandwidthintensive applications stretch network capabilities and resources, but also complement, add value, and enhance every business process. Networks must provide secure, predictable, measurable, and sometimes guaranteed services. Achieving the required Quality of Service (QoS) by managing the delay, delay variation (jitter), bandwidth, and packet loss parameters on a network becomes the secret to a successful end-to-end business solution. Thus, QoS is the set of techniques to manage network resources. QoS refers to the ability of a network to provide better service to selected network traffic over various underlying technologies including Frame Relay, Asynchronous Transfer Mode (ATM), Ethernet and 802.1 networks, SONET, and IProuted networks. Typically, networks operate on a best-effort delivery basis, which means that all traffic has equal priority and an equal chance of being delivered in a timely manner. When congestion occurs, all traffic has an equal chance of being dropped. Issues like; when speaking with customers or co-workers over an IP phone without QoS enabled, there is a good chance that some packets will get dropped causing lost or choppy conversation. And if someone decides to transfer a large file, that process could hog all of the bandwidth and prevent any VoIP conversations while the transfer takes place. In any environment this is unacceptable When you configure QoS, you can select specific network traffic, prioritize it according to its relative importance, and use congestion-management and congestion-avoidance techniques to give preferential treatment. Implementing QoS in your network makes network performance more predictable and bandwidth utilization more effective. Auto QoS makes implementing QoS very easy. By enabling QoS, Supporting dedicated bandwidth. Improving loss characteristics. Avoiding and managing network congestion. Shaping network traffic. Setting traffic priorities across the network. Cisco has a white paper on Auto QoS: http://www.cisco.com/en/us/tech/tk543/tk759/technologies_white_paper09186a00801348bc.shtml Equipment used in this lab: 1 Cisco 2xxx router. 1 Cisco 3550 layer three switch (SMI or EMI) 2 Cisco 79x0 IP Phones 5 Cat 5 RJ45 Ethernet patch cables Internet access
1 2 ABC 4 5 GH I JKL 7 8 PQRS T UV 0 OPER 3 DEF 6 MNO 9 WXY Z # CISCO IP PH ONE 7941 SERIES -? + 1 2 ABC 4 5 GHI JKL 7 8 PQ RS TUV 0 OPER 3 DEF 6 MNO 9 WXYZ # CISCO IP PHONE 7941 SERIES -? + Cisco VoIP CME Lab 19 QoS Configuring Auto QoS Below is the basic network configuration we will be using in this lab. You can expand the design as needed. Cisco 3550 192.168.3.2 Internet DSL/Cable Provided Router VLAN 1 VLAN 3 192.168.3.x (dhcp) DSL/Cable Modem 192.168.1.1 Cisco 2610XM or 28x1 fa0/0.1 192.168.1.x (dhcp) fa0/0.2 192.168.2.1 fa0/0.3 192.168.3.1 * 192.168.2.x 192.168.2.x (dhcp) (dhcp) VLAN 2 * This lab assumes that you have configured your lab by following NetCertLabs VoIP CME labs 1 through 12 with all interfaces configured, IP addresses assigned, and other configurations completed. What is Auto QoS? AutoQoS is a macro that applies the recommended Architecture and settings for Voice, Video, and Integrated Data (AVVID) QoS settings to a specific port. Quality of Service is a very complex set of configurations and settings which could take years to master. However, Cisco has developed macro s that utilize best-practice recommendations enabling components based upon the network environment. Also, by using the QoS macro, you are less likely to make mistakes and aid you in consistency across multiple devices. Many engineers run the Auto QoS macro then fine tune specific elements to meet their specific needs. Cisco IP phones are usually connected directly to ports. Optionally, you can attach a PC to the phone and use the phone s built-in switch. This saves on cabling and switches thus reducing costs to the company. This is the recommended practice because the phone and switch automatically marks the different data types for QoS. The traffic that comes from the phone can be marked with an 802.1Q or 802.1p tag. The tag contains a VLAN ID and CoS (Class of Service) value. When you configure the port to trust the CoS value that comes from the phone, the switch uses the CoS value to prioritize the phone traffic over other traffic. Auto QoS supports Cisco IP phones with the auto qos voip cisco-phone interface (auto qos vopi ciscosoftphone) configuration command. When you enter the auto qos voip cisco-phone interface configuration command on a port that is configured to support an IP phone and to which an IP phone is connected, the Auto QoS feature does the following: If QoS was not already enabled, enables QoS globally. If VLAN-based QoS was configured for the port, reverts to the default port-based Sets the port trust state to trust CoS.
Creates and applies a trust-cos QoS policy to ports on switching modules with non-gigabit Ethernet ports, which do not support port trust. There are a few things you should remember before you run the Auto QoS command on a router or a switch. They are: Enable autoqos before you configure other QoS commands. If necessary, you can modify the QoS configuration after the autoqos configuration completes. Enable autoqos before you configure other QoS commands. If necessary, you can modify the QoS configuration after the autoqos configuration completes. AutoQoS cannot attach a policy map to an interface if there is already a policy map attached. Do not modify a policy map or class map that includes AUTOQOS in its name. You cannot configure autoqos on the following: o Port-channel interfaces o LAN interfaces (also known as switch virtual interfaces or SVIs) o Tunnel interfaces o Loopback interfaces o Sub interfaces on any type of interface Using your favorite telnet or SSH program, log into your CME router and switch; enter the enhanced mode and then into the configuration mode. We start by entering the interface we want to configure Auto QoS for marked traffic on. LAB_2851(config)#interface serial0/0/0 LAB_2851(config-if)#auto qos voip trust To see the configuration changes made by Auto QoS, enter the command show running-config. LAB_2851#show running-config 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 Serial0/0/0 no ip address auto qos voip trust clock rate 2000000 service-policy output AutoQoS-Policy-Trust rmon event 33333 log trap AutoQoS description "AutoQoS SNMP traps for Voice Drops" owner AutoQoS rmon alarm 33333 cbqoscmdropbitrate.82.9499905 30 absolute risingthreshold 1 33333 falling-threshold 0 owner AutoQoS
On some IOS versions you can configure Auto QoS for the Cisco IP Communicator with the following command. LAB_2851(config-if)#auto qos voip cisco-softphone Also, Auto QoS support for Cisco IP phones. Auto QoS is supported on many Cisco switches too. And they too are configured on a port by port basis. When auto-qos is enabled, the auto qos voip interface configuration command and the generated configuration are added to the running configuration. Before configuring auto-qos on a switch, you should know: In most IOS s, auto-qos configures the switch only for VoIP with Cisco IP phones. To take advantage of the auto-qos defaults, do not configure any standard-qos commands before entering the auto-qos commands. If necessary, you can fine-tune the QoS configuration, but we recommend that you do so only after the auto-qos configuration is completed. You can enable auto-qos on static, dynamic-access, voice VLAN access, and trunk ports. By default, the CDP is enabled on all interfaces. For auto-qos to function properly, do not disable the CDP. Policing is not enabled with auto-qos. You can manually enable policing, On your lab switch enter the following commands to enable Auto QoS. LAB_3550(config)#interface fastethernet 0/13 LAB_3550(config)#interface fastethernet 0/14 Entering the show running config command shows us the changes made on our switch after we ran the Auto QoS command. LAB_3550#show running config mls qos map cos-dscp 0 8 16 26 32 46 48 56 mls qos min-reserve 5 170 mls qos min-reserve 6 10 mls qos min-reserve 7 65 mls qos min-reserve 8 26 mls qos interface FastEthernet0/13 switchport mode dynamic desirable mls qos trust device cisco-phone mls qos trust cos auto qos voip cisco-phone wrr-queue bandwidth 20 1 80 1 wrr-queue min-reserve 1 5 wrr-queue min-reserve 2 6 wrr-queue min-reserve 3 7 wrr-queue min-reserve 4 8 wrr-queue cos-map 1 0 1 2 4 wrr-queue cos-map 3 3 6 7 wrr-queue cos-map 4 5
priority-queue out The output below shows the Auto QoS results when you use the trust option. interface FastEthernet0/15 switchport mode dynamic desirable mls qos trust cos auto qos voip trust wrr-queue bandwidth 20 1 80 1 wrr-queue min-reserve 1 5 wrr-queue min-reserve 2 6 wrr-queue min-reserve 3 7 wrr-queue min-reserve 4 8 wrr-queue cos-map 1 0 1 2 4 wrr-queue cos-map 3 3 6 7 wrr-queue cos-map 4 5 priority-queue out As you have learned, it is very easy to use Auto QoS to improve the quality of service on your networks. After you have setup and tested this lab, please blog your experience on our blog site at: http://netcertlabs.com/netcertlabs-blog Thank You,