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> Voice over Wireless LAN
Technical Solution Guide
Enterprise Solutions Engineering
Document Date: December 15, 2005
Document Version: 1.0
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Voice over Wireless LAN Solution Guide v1.0 December 2005 Copyright © 2005 Nortel Networks All rights reserved. December 2005. The information in this document is subject to change without notice. The statements, configurations, technical data, and recommendations in this document are believed to be accurate and reliable, but are presented without express or implied warranty. Users must take full responsibility for their applications of any products specified in this document
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Voice over Wireless LAN Solution Guide v1.0 December 2005 Abstract This document is intended to define the Voice over Wireless LAN (VoWLAN) solution to assist sales engineers in creating the best design to fit the customer’s environment while at the same time eliminating common design errors. The products central to this document are the Nortel WLAN Security Switch 2300 (models 2350, 2360, and 2380), Nortel WLAN Access Point 2330, Nortel WLAN Handset (models 2210, 2211, and 22
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Voice over Wireless LAN Solution Guide v1.0 December 2005 TABLE OF CONTENTS 1. EXECUTIVE SUMMARY ................................................................................................................. 6 1.1 CHALLENGES ................................................................................................................................. 6 1.1.1 High overhead of 802.11 .............................................................................................
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Voice over Wireless LAN Solution Guide v1.0 December 2005 3.2.2 WLAN Handset 2210/11/12 .................................................................................................... 58 3.3 DNS SERVER ............................................................................................................................... 59 3.4 TFTP SERVER .............................................................................................................................. 59
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Voice over Wireless LAN Solution Guide v1.0 December 2005 1. Executive summary Voice over Wireless LAN (VoWLAN) represents the coming together of two important and rapidly growing technologies — WLAN and Internet Protocol (IP) Telephony. By seamlessly integrating the IP Telephony system with WLAN infrastructure, VoWLAN provides users with high-quality mobile voice and data communications throughout the workplace. This document has two main purposes in defining the aspects of a
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Voice over Wireless LAN Solution Guide v1.0 December 2005 1.1.3 Power adjustments and variable capacity The WLAN market has matured to the point that most vendor product solutions have dynamic mechanisms in place for adjusting channels, adjusting power, and filling coverage holes, all in response to changes in the Radio Frequency (RF) environment. Although the robustness of the mechanisms and features varies, all pose the same basic challenge to engineering voice networks. D
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Voice over Wireless LAN Solution Guide v1.0 December 2005 QoS over the air techniques generally require complementary feature support by client and AP alike, which means that some legacy devices or products that are slower to implement certain features ultimately can impact the overall solution for voice with respect to QoS. The Hybrid Coordination Function (HCF) is designed to smooth this transition by supporting a combination of channel access methods, both new and legacy. Ho
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Voice over Wireless LAN Solution Guide v1.0 December 2005 2.1 Applications Following is a brief description of the various voice applications. 2.1.1 WLAN Handset 2210/11/12 voice The WLAN Handsets 2210, 2211, and 2212 work only in a Nortel Succession 3.0 (and later) environment coordinated with a Communication Server (CS) 1000 or Meridian 1. These handsets communicate with the Nortel call server through the Unified Network IP Stimulus (UNIStim) protocol. The media path of the
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Voice over Wireless LAN Solution Guide v1.0 December 2005 Dell Axim X5 (CPU >= 400 MHz) Dell Axim X3/C3i iPAQ h5550/h5555 Toshiba e750/e755 Toshiba e800/e805 2.1.4 MCS Client Multimedia Communication Server (MCS) 5100 is an application services delivery solution that provides productivity, personalization, and collaborative applications that transform the way users communicate. These SIP-enabled applications work together with an enterprise’s existing voice a
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Voice over Wireless LAN Solution Guide v1.0 December 2005 location. The three architectures can be combined as desired, so they are not mutually exclusive choices. The basic architectures are: Distributed Campus Centralized Campus Branch Office The two AP connection types are: Direct connection Distributed AP (DAP) A direct connection is defined as an AP with a physical connection to a WLAN Security Switch 2300 and which is configured as an extension to the p
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Voice over Wireless LAN Solution Guide v1.0 December 2005 Figure 1: Distributed Campus architecture 2.2.1.2 Centralized Campus A second architectural option is to centralize the security switches within a data center environment. The model most suited for this role is the WSS 2380, which has four gigabit interfaces, no PoE ports, and supports up to 120 active APs. Each AP is powered at the edge by a PoE switch or a PoE injector, and has a DAP connection back to the centra
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Voice over Wireless LAN Solution Guide v1.0 December 2005 Figure 2: Centralized Campus architecture 2.2.1.3 Branch Office The WLAN 2300 can also be deployed in a small branch office environment. Usually this type of environment requires only a handful of APs, probably anywhere from one to six. The WSS 2350 is the model best suited for this environment, supporting up to three AP 2330s per WSS 2350, including one PoE port for direct connection. A PoE injector or PoE switch
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Voice over Wireless LAN Solution Guide v1.0 December 2005 Figure 3: Branch Office architecture 2.2.1.4 Combining architectures Up to now, architecture has been discussed in binary terms—this topology or that topology. However, the WLAN 2300 solution is not restrictive in this way. The three architectures can be combined in many different ways within the same network, and as will be shown later, VoWLAN is generally not restricted by these architectural choices. However, it
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Voice over Wireless LAN Solution Guide v1.0 December 2005 Figure 4: Combined architecture 2.2.1.5 Third-party AP support In some cases, integrating the WLAN 2300 series into an existing fat-AP deployment may be required or desired. For instance, fat APs may have been deployed in a limited fashion and the WLAN 2300 is a new network expansion. The WSS 2300 extends all its AAA features to the third- party AP, including the ability to consolidate all handsets into one voice VL
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Voice over Wireless LAN Solution Guide v1.0 December 2005 Figure 5: Network with third-party APs The WSS 2300 supports many models of third-party APs with a few restrictions—see WSS 2300 Release Notes. All models of WSS 2300 have support for third-party APs, although implementation specifics may vary. In many cases, Nortel also supports VoWLAN over third-party APs. The APs must be L2 or directly attached to the WSS 2300. Note that this may require extending VLANs in the C
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Voice over Wireless LAN Solution Guide v1.0 December 2005 the ES PSU 10 can provide up to 75 W of power to PoE devices through the ES 460-24T-POE. This means that when running on battery or redundant DC power, only about 10 or 11 APs can be powered. If the deployment of the network calls for more than 10 APs on any ES 460-24T- POE switch, Nortel highly recommends the NES as the external power supply option instead of the ES PSU 10. The NES can provide a full 200 W to end devices
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Voice over Wireless LAN Solution Guide v1.0 December 2005 MLT to the L2 switch. In this configuration, all APs in the branch must be DAPs powered by the L2 switch or a separate PoE injector. In most cases, you should disable spanning tree on the switch port to which a DAP is connected. If spanning tree is not disabled, there is a possibility that the AP will never connect to a WSS 2300 because of timing differences between spanning tree and the AP switch detection timers. In
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Voice over Wireless LAN Solution Guide v1.0 December 2005 beneficial to overall voice quality and media scalability. These are some of the dynamics to consider when making this choice. Ultimately you want to carefully control the number of data devices sharing radio resources with voice devices, and you should gear your choices towards this end. For example, suppose that you have a large amount of Centrino laptops in the campus. If you enable 802.11g mode, it becomes very like
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Voice over Wireless LAN Solution Guide v1.0 December 2005 maximum call capacity is not that much higher than the 802.11b channel reuse case (only up to four times as much). By contrast, 802.11a offers a much greater channel space. Channel reuse factors can be as high as 12 or more, depending on regulatory region. Borrowing the assumptions from the previous example (50 mW transmit power and channel reuse of 12), the same scenario has none of the same caps on call capacity. Each
