Chapter 2 Survey Tools

Survey Tools for Packet Jitter

Survey Tools for Packet Jitter

Typically, voice packets are sent every 20 ms. Voice calls are usually bursty, consisting of a group of tightly packed packets in a transmit direction followed by a tightly packed group in a receive direction. The users of WIPT are typically mobile users who have active calls while moving between WLAN coverage cells and hence roaming between coverage cells. AirMagnet Surveyor provides a tool for this type of possible packet jitter and the trace decode tool provides interpacket timings. Over-the-air packet jitter tools measure the WLAN packets. A WIPT call will also at some point be on a wired segment or segments, which could also be a source of jitter. Figure 2-13shows the AirMagnet jitter tool.

Figure 2-13 AirMagnet Jitter Tool

The AirMagnet jitter tool allows for the monitoring of a WIPT client during an active call. The tool reports the standard deviation (STD) of the transmit side and the receive side of the client packets. It reports the average interpacket delay plus the minimum and maximum delays. The jitter measurement of this tool is just from access point to WIPT client and WIPT client to the access point. This is not an end-to-end measurement of jitter or latency for a VoIP call.

Figure 2-14shows there is significant data and noise on all channels. The effect of the data and noise on the quality of voice is shown with STD values of 4.87 and 6.02. The channel utilization is 30.65. The Cisco AVVID design guide states for quality VoIP calls the Delay Variation (Jitter) should not exceed 30 ms. In an office with heavy use of 802.11, the average in-packet delay might vary from 19ms to a high of 32ms, and the average out-packet delay might vary from 18 ms to a high of 41 ms. Those delay averages would produce intermittent but noticeable jitter during active calls and a noticeable delay during roams.

Site Survey Guide for Deploying Cisco 7920 IP Phones

 

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Cisco Systems 7920 manual Survey Tools for Packet Jitter, AirMagnet Jitter Tool
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7920 specifications

Cisco Systems, a leading player in the global networking and communications technology sector, designed the Cisco 7920 Wireless IP Phone for mobile professionals seeking seamless connectivity in various environments. Primarily aimed at enhancing communication within enterprise settings, this wireless device offers a plethora of features that cater to the specific needs of businesses.

At the core of the Cisco 7920 is its robust wireless functionality. It operates on IEEE 802.11b/g wireless protocols, allowing users to connect effortlessly to Wi-Fi networks. This flexibility enables employees to communicate effectively from various locations within an office space, promoting mobility and collaboration without being tethered to a desk.

The ergonomic design of the Cisco 7920 prioritizes user comfort. Its lightweight casing and intuitive button layout ensure that users can navigate the interface with ease. The device is equipped with a vibrant color display, allowing for clear visibility of caller ID, call status, and menu options, enhancing the user experience further. Additionally, the handset supports a wide variety of languages, making it suitable for global teams.

In terms of features, the Cisco 7920 is loaded with advanced capabilities. It supports voice over IP (VoIP), delivering high-quality audio and ensuring reliable communication. Users benefit from features like a contextual menu, call hold, transfer, conference calling, and voicemail access on the go. The phone also offers a wide range of ringtones, allowing customization to suit personal preferences or company branding.

Security is a crucial aspect of modern telecommunications, and the Cisco 7920 does not fall short. It incorporates industry-standard security protocols such as Wired Equivalent Privacy (WEP) and Wi-Fi Protected Access (WPA), safeguarding communications from potential threats.

Moreover, the Cisco 7920 integrates seamlessly with Cisco Unified Communications Manager, enabling centralized management and control. This integration ensures that IT departments can deploy, manage, and troubleshoot devices efficiently, streamlining operations while ensuring optimal performance.

In conclusion, the Cisco 7920 Wireless IP Phone stands out as a versatile communication tool designed for the fast-paced workplace. Its combination of wireless connectivity, ergonomic design, advanced features, and robust security makes it an essential accessory for businesses looking to elevate their communication strategies. With its established reputation, Cisco continues to support companies in achieving seamless connectivity and effective collaboration.
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