Cisco 71642 User Manual

Vocera IP Phone Deployment in Cisco Unified Wireless Network Infrastructure
Document ID: 71642
Introduction Prerequisites
Requirements Components Used Conventions
Unicast−Multicast Delivery Method Multicast−Multicast Delivery Method Router and Switch Multicast Configuration Enable IP Multicast Routing Enable PIM on an Interface Disable Switch VLAN IGMP Snooping Multicast Enhancements in Version 4.0.206.0 and Later
Deployment Scenarios
Single Controller Deployment Multiple Controller Layer 2 Deployment Multiple Controller Layer 3 Deployment
VoWLAN Deployments: Ciscos Reccommendations
Recommendations for Multi−Floor Buildings, Hospitals, and Warehouses
Security Mechanisms Supported
LEAP Considerations
Wireless Network Infrastructure
Voice, Data and Vocera VLANs Network Sizing
Switch Recommendations Deployments and Configuration
Badge Configuration
Tune AutoRF for Your Environment Wireless Network Infrastructure Configuration
Create Interfaces Create the Vocera Voice Interface Wireless−Specific Configuration WLAN Configuration Configure Access Point Detail Configure the 802.11b/g Radio
Wireless IP Telephony Verification Association, Authentication, and Registration Common Roaming Issues
The Badge Loses Connection to the Network or Voice Service is Lost when Roaming Badge Loses Voice Quality while Roaming
Audio Problems
One−sided Audio Choppy or Robotic Audio Registration and Authentication Problems
Appendix A
AP and Antenna Placement Interference and Multipath Distortion Signal Attenuation
NetPro Discussion Forums − Featured Conversations Related Information
Introduction
This document provides design considerations and deployment guidelines for the implementation of the Vocera® Badge Voice over WLAN (VoWLAN) technology on the Cisco Unified Wireless Network infrastructure.
Note: Support for Vocera products should be obtained directly from Vocera support channels. Cisco Technical Support is not trained to support Vocera−related issues.
This guide is a supplement to the Cisco Wireless LAN Controller Deployment Guide and only addresses the configuration parameters that are particular to Vocera VoWLAN devices in a lightweight architecture. Refer to Deploying Cisco 440X Series Wireless LAN Controllers for more information.
This document builds upon ideas and concepts presented in the Cisco IP Telephony Solution Reference Network Design (SRND) and the Cisco Wireless LAN SRND. Both of these SRNDs are available online at http://www.cisco.com/en/US/netsol/ns656/networking_solutions_program_home.html.
Prerequisites
Requirements
It is assumed that readers are familiar with the terms and concepts presented in the Cisco IP Telephony SRND and the Cisco Wireless LAN SRND. Both of these SRNDs are available online at http://www.cisco.com/en/US/netsol/ns656/networking_solutions_program_home.html.
Components Used
This document is not restricted to specific software and hardware versions.
Conventions
Refer to Cisco Technical Tips Conventions for more information on document conventions.
Executive Summary
This table summarizes the four key functions and how they behave within a Cisco Unified Wireless network.
Single
Controller
Controller−to−Controller
Layer 2 Roaming
Controller−to−Controller
Layer 3 Roaming
Badge−to−Badge No special
configuration
No special configuration No special configuration
Badge−to−Phone No special
configuration
Badge−to−Broadcast
Badge Location No special
Enable Controller Multicast
configuration
No special configuration No special configuration
Enable Controller Multicast
Disable Vocera VLAN IGMP−Snooping or run
4.0.206.0 or later
No special configuration No special configuration
4.0.206.0 or later
Vocera Badge Overview
The communication badges allow a wearer instant communication with any other badge wearer as well a Private Branch Exchange (PBX) integration and badge location tracking. The utilization of an 802.11b/g wireless network requires the use of multicast and UDP unicast packet delivery with limited requirements for Quality of Service (QoS) as of Vocera Server Software release 3.1 (Build 1081). The encryption capabilities are 64/128 bit Wired Equivalent Privacy (WEP), Temporal Key Integrity Protocol (TKIP), Message Integrity Check (MIC), and Cisco Temporal Key Integrity Protocol (CKIP) combined with the authentication capabilities of Open, Wi−Fi Protected Access−Pre−shared Key (WPA−PSK), WPA−Protected Extensible Authentication Protocol (PEAP) and Lightweight Extensible Authentication Protocol (LEAP).
With the push of a button, the Vocera server responds with Vocera, which is a prompt to issue commands such as record, where (am I) /is..., call, play, broadcast, messages, and so forth. The Vocera server provides the necessary services and/or call setup to complete the request.
Vocera's 802.11b capable Communication System makes use of proprietary voice compression and the use of a UDP port range. The Vocera System software runs on a Windows server that manages call set up, call connection and user profiles. They have partnered with Nuance 8.5 Speech Recognition and Voiceprint software in order to enable badge voice communications. Vocera recommends a separate Windows server to run the Vocera Telephony Solutions Software to enable Plain Old Telephone Service (POTS) connectivity with the badges.
Vocera Call Capacity Considerations
See the Network Sizing section of this document for further details.
Vocera Communications Server Capacity
Refer to the Vocera Communications System Specifications for more information on Vocera Server sizing matrix.
The Vocera Solution
The Vocera Badge utilizes both unicast and multicast packet delivery to provide several key features that make up this complete solution. Here are four of the essential features that rely on proper packet delivery. Also provided is a basic understanding of how each feature uses the underlying network for delivery and functionality.
Badge to Badge CommunicationsWhen one Vocera user calls another user, the badge first contacts
the Vocera server, which looks up the IP address of the badge of the callee and contacts the badge user to ask the user if they can take a call. If the callee accepts the call, the Vocera server notifies the calling badge of the IP address of the callee badge to setup direct communication between the badges with no further server intervention. All communication with the Vocera server uses the G.711 codec and all badge−to−badge communication uses a Vocera proprietary codec. Badge Telephony CommunicationWhen a Vocera Telephony server is installed and setup with a
connection to a PBX, a user is able to call internal extensions off of the PBX or outside telephone lines. Vocera allows users to make calls by either saying the numbers (five, six, three, two) or by creating an address book entry in the Vocera database for the person or function at that number (for example, pharmacy, home, pizza) the Vocera server determines the number that is being called, either by intercepting the numbers in the extension or by looking the name up in the database and selecting the number. The Vocera server then passes that information to the Vocera Telephony server which connects to the PBX and generates the appropriate telephony signaling (for example, DTMF). All communication between the badge and Vocera server and Vocera server and Vocera Telephony server use the G.711 codec over unicast UDP. Vocera BroadcastA Vocera Badge user can call and communicate to a group of Vocera badge
wearers at the same time by using the Broadcast command. When a user broadcasts to a group, the user's badge sends the command to the Vocera server who then looks up the members of a group, determines which members of the group are active, assigns a multicast address to use for this broadcast session, and sends a message to each active users badge instructing it to join the multicast group with the assigned multicast address. Badge Location FunctionThe Vocera server keeps track of the access point to which each active
badge is associated as each badge sends a 30 second keep alive to the server with the associated BSSID. This allows the Vocera system to roughly estimate the location of a badge user. This function has a relatively low degree of accuracy because a Badge might not be associated to the access point to which it is closest.
Vocera's Infrastructure Planning
The Vocera whitepaper Vocera Infrastructure Planning Guide , describes the site survey minimum requirements that show that the badge should have a receive signal strength minimum of −65 dBm, a signal−to−noise ratio greater than 25 db and proper access point overlap and channel separation. Although the badges use a similar omni directional antenna as a notebook that is used for a site survey, it does not mimic the behavior of the badge very well, given the wearers' affects on signal strength. Given this unique requirement and this behavior of the transmitting device, the use of the Cisco Architecture and Radio Resource Management is ideal in order to make sure there is a lack of unusual radio frequency (RF) site characteristics.
The Vocera badge is a low powered device, worn next to the body with limited signal error correction capabilities. The Vocera requirements in this document can be easily achieved. However, it can become overwhelmed if there are too many SSIDs for it to process and allow the badge to work effectively.
Architecture Overview
Figure 1General Multicast Forward and Prune with Lightweight Access Point Protocol (LWAPP) Wireless
Multicast in an LWAPP Deployment
Understanding multicast within an LWAPP deployment is necessary to deploy the Vocera broadcast function. This document later covers the essential steps to enable multicast within the controller−based solution. There are currently two delivery methods that the LWAPP controller uses to deliver multicast to the clients:
Unicast−Multicast Multicast−Multicast
Unicast−Multicast Delivery Method
The unicast−multicast delivery method creates a copy of every multicast packet and forwards it to every access−point. When a client sends a multicast join to the wireless LAN, the access point forwards this join through the LWAPP tunnel to the controller. The controller bridges this multicast join onto it's directly connected local area network connection that is the default VLAN for the associated WLAN of the client. When an IP multicast packet arrives from the network to the controller, the controller replicates this packet with an LWAPP header for each access point that has a client within the wireless domain who has joined this specific group. When the source of the multicast is also a receiver within the wireless domain, this packet is also duplicated and forwarded back to the same client who sent this packet. For Vocera badges, this is not the preferred method of multicast delivery within the LWAPP controller solution. The unicast delivery method works with small deployments. However, due to the considerable overhead on the Wireless LAN Controller (WLC), this is never the recommended multicast delivery method.
Figure 2LWAPP Multicast−Unicast
Note: If AP Group VLANs are configured, and an IGMP join is sent from a client through the controller, it is
placed on the default VLAN of the WLAN that the client is on. Therefore, the client might not receive this multicast traffic unless the client is a member of this default broadcast domain.
Multicast−Multicast Delivery Method
The multicast−multicast delivery method does not require the controller to replicate each multicast packet received. The controller is configured for an un−used multicast group address that each access point becomes a member of. With Figure 3, the multicast group defined from the WLC to the access point is 239.0.0.65. When a client sends a multicast join to the WLAN, the access point forwards this join through the LWAPP tunnel to the controller. The controller forwards this link−layer protocol onto it's directly connected local area network connection that is the default VLAN for the associated WLAN of the client. The router that is local to the controller then adds this multicast group address to that interface for forwarding ((*,G)) entry. With Figure 3, the example multicast join was sent to the multicast group 239.0.0.30. When the network now forwards multicast traffic, the multicast address of 239.0.0.30 is forwarded to the controller. The controller then encapsulates the multicast packet into an LWAPP multicast packet addressed to the multicast group address (example here is 239.0.0.65) that is configured on the controller and forwarded to the network. Each access point on the controller receives this packet as a member of the controllers multicast group. The access point then forwards the clients/servers multicast packet (example here is 239.0.0.30) as a broadcast to the WLAN/SSID identified within the LWAPP multicast packet.
Note: If you improperly configure your multicast network, you could end up receiving another controller's access point multicast packets. If the first controller has to fragment this multicast packet, the fragment is forwarded to the network and each access point must spend time to drop this fragment. If you allow all traffic such as anything from the 224.0.0.x multicast range, this is also encapsulated and subsequently forwarded by each access point.
Figure 3LWAPP Multicast−Multicast
Router and Switch Multicast Configuration
This document is not a network multicast configuration guide. Refer to Configuring IP Multicast Routing for a complete implementation story. This document covers the basics to enable multicast within your network environment.
Enable IP Multicast Routing
IP multicast routing allows the Cisco IOS® software to forward multicast packets. The ip multicast−routing global configuration command is required to allow multicast to function in any multicast enabled network. The ip multicast−routing command should be enabled on all routers within your network between the WLC(s) and their respective access points.
Router(config)#ip multicast−routing
Enable PIM on an Interface
This enables the routing interface for Internet Group Management Protocol (IGMP) operation. The Protocol Independent Multicast (PIM) mode determines how the router populates its multicast routing table. The example provided here does not require the rendezvous point (RP) to be known for the multicast group and therefore sparse−dense−mode is the most desirable given the unknown nature of your multicast environment. This is not a multicast recommendation to be configured to work although the Layer 3 interface directly connected to your controller should be PIM enabled for multicast to function. All interfaces between your WLC(s) and their respective access points should be enabled.
Router(config−if)#ip pim sparse−dense−mode
Disable Switch VLAN IGMP Snooping
IGMP snooping allows a switched network with multicast enabled to limit traffic to those switchports that have users who want multicast to be seen while pruning the multicast packets from switchports that do not wish to see the multicast stream. In a Vocera deployment, it can be undesirable to enable CGMP or IGMP snooping on the upstream switchport to the controller with software releases earlier than 4.0.206.0.
Roaming and multicast are not defined with a set of requirements to verify that multicast traffic can follow a subscribed user. Although the client badge is aware that it has roamed, it does not forward another IGMP join to make sure that the network infrastructure continues to deliver the multicast (Vocera broadcast) traffic to the badge. At the same time, the LWAPP access point does not send a general multicast query to the roamed client to prompt for this IGMP join. With a Layer 2 Vocera network design, disabling IGMP snooping allows traffic to be forwarded to all members of the Vocera network no matter where they roam. This ensures that the Vocera broadcast feature works irrespective of where the client roams. Disabling IGMP snooping globally is a very undesirable task. It is recommended that IGMP snooping only be disabled on the Vocera VLAN that is directly connected to each WLC.
Refer to Configuring IGMP Snooping for more information.
Router(config)#interface vlan 150 Router(config−if)#no ip igmp snooping
Multicast Enhancements in Version 4.0.206.0 and Later
With the release of 4.0.206.0, Cisco introduces an IGMP query to allow users to roam at Layer 2 by sending a general IGMP query when this occurs. The client then responds with the IGMP group that they are a member of and this is bridged to the wired network as described earlier in this document. When a client roams to a controller that does not have Layer 2 connectivity, or a Layer 3 roam, synchronous routing is added for multicast source packets. When a client, who has completed a Layer 3 roam sources a multicast packet from the wireless network, the foreign controller encapsulates this packet in the Ethernet over IP (EoIP) in IP tunnel to the anchor controller. The anchor controller then forwards that to the wireless clients locally associated as well as bridge this back to the wired network where it is routed using normal multicast routing methods.
Deployment Scenarios
These three deployment scenarios cover best practices and design parameters to help with a successful Vocera Badge deployment:
Single Controller Deployment Multiple Controller Layer 2 Deployment Multiple Controller Layer 3 Deployment
Understanding how the Vocera Badge features interact within an LWAPP split MAC environment is essential. With all deployment scenarios, multicast should be enabled and aggressive load balancing should be disabled. All badge WLANs should be contained within the same broadcast domain across your entire network.
Figure 4
Single Controller Deployment
This is the most straight forward deployment scenario. It allows you to deploy the Vocera Badge solution with little deployment concerns. Your network must be enabled for IP multicast routing only to allow the access points to receive the LWAPP multicast packets. If required, you can limit network multicast complexity by configuring all routers and switches with the controllers multicast group.
With multicast configured globally on the controller, the proper SSID, security settings, and all the access points registered the Vocera Badge solution and all its functions operates as expected. With the Vocera Broadcast function, a user roams and the multicast traffic follows as expected. There are no extra settings required to be configured to allow this solution to function properly.
When a Vocera Badge sends a multicast message, as it does with the Vocera Broadcast, it is forwarded to the controller. The controller then encapsulates this multicast packet within an LWAPP multicast packet. The network infrastructure forwards this packet to every access point that is connected to this controller. When the access point receives this packet, it then looks at the LWAPP multicast header to determine which WLAN/SSID it then broadcasts this packet to.
Figure 5Single Controller in Multicast−Multicast Mode
Multiple Controller Layer 2 Deployment
Multiple controllers must all have connectivity to each other via the same Layer 2 broadcast domain. Both controllers are configured for multicast as shown, using the identical access point multicast groups on each controller to limit fragmentation. With the assumption that this Layer 2 broadcast domain is connected via a common switch or a common set of switches, CGMP/IGMP snooping on these switches must be disabled for this single VLAN or run 4.0.206.0 or later WLC software. With the Vocera Broadcast function and a user roam from an access point on one controller to an access point on a different controller, there is no mechanism for IGMP joins to be forwarded to the new Layer 2 port for IGMP snooping to work. Without an IGMP packet reaching the upstream CGMP or IGMP capable switch, the specified multicast group is not forwarded to the controller and therefore is not received by the client. In some cases this might work, if a client that is part of the same Vocera Broadcast group has already sent this IGMP packet before the roaming client roams onto the new controller With the advantages of version 4.0.206.0, a client who roams to another controller as a Layer 2 roam receives a general IGMP query immediately after authentication. The client should then respond with the interested groups and the new controller is then bridged this to the locally connected switch. This allows the advantages of IGMP and CGMP on your upstream switches.
You can create additional badge SSIDs and Layer 2 domains for separate badge networks as long as your network is configured to pass multicast traffic appropriately. Also, each Vocera Layer 2 broadcast domain created must exist everywhere a controller is connected to the network so as not to break multicast.
Figure 6Multiple Controller Layer 2 Deployment
Multiple Controller Layer 3 Deployment
The Layer 3 roaming deployment strategy should only be used with controller−to−controller roaming with WLC software release 4.0.206.0 or later. If a client that has been connected to the Vocera broadcast group and receives the appropriate multicast stream and roams to another controller as a Layer 3 roam with the LWAPP Layer 3 roaming configured, it is queried for interested multicast groups. The client, when sourcing to the same Vocera broadcast group, has these packets delivered to the anchor controller through the EoIP tunnel
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