Cisco Systems 7920 IP manual Layer 2 Roaming

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Note: Any references to roam or roaming throughout the remainder of this document is in the context of mid−call roaming.

As it relates to roaming, the Cisco 7920 IP Phone currently only supports Layer 2 roaming. This means that a Cisco 7920 IP Phone can roam between APs that have coverage for a single Layer 2 subnet, but calls are dropped when the phone roams into the AP coverage for another Layer 2 network.

Layer 2 Roaming

Layer 2 Roaming occurs when a WLAN device, for example the Cisco 7920, physically moves enough that its radio associates to a different AP. The original and the updated AP offer coverage for the same IP subnet, so that the WLANs client are still valid after the roam.

The Cisco 7920 performs an Layer 2 roam for the following reasons:

∙When the Cisco 7920 initially boots, this is considered a roaming event because it is associating with a new AP.

∙The Cisco 7920 does not receive beacons from the associated AP, and therefore believes that the AP is no longer available. If three consecutive beacons are not received by the Cisco 7920, and its unicast packet to the AP is not acknowledged, the Cisco 7920 begins the roaming process to another AP.

∙The Cisco 7920 periodically scans for better APs. Because the initial startup is considered to be a roaming event, all client stations have roamed at least once. After the roam process has completed, the client station maintains the list of eligible roam targets. When all AP information is received (channel update, current AP update), the phone evaluates its current AP with the list of eligible roam targets. If conditions change on the current AP (RSSI low or QBSS high) so that one of the APs in the client's stored list now appears to be a better choice than the current AP, the phone starts a handoff procedure to associate with the AP.

∙The Service Set Identifier (SSID) or encryption type on the Cisco 7920 has changed.

Once one of the events above occurs, the Layer 2 roaming process proceeds as follows:

1.The Cisco 7920 looks at its list of eligible roam targets (APs with a matching SSID or encryption type) and chooses the best candidate. The Cisco 7920 then attempt to associate and authenticate to

Cisco − Wireless IPT Design Guide for the Cisco 7920 IP Phone

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Contents Table of Contents Requirements IntroductionPrerequisites Components Used Cisco 7920 IP Phone OverviewWlan Overview RF Overview Site Surveys and Design RecommendationsRssi VoIP QoS∙ Delay Variation Jitter Not to exceed 30ms Security for the Cisco 7920 and Wlan Networks Number of 802.11b IP Phones per AP Network SizingNumber of 802.11b Devices per AP Page Numbers of 802.11b Phones per Layer 2 Subnet or Vlan Understanding Roaming Terminology Understanding Layer 2 and Layer 3 RoamingLayer 2 Roaming Page Layer 3 Roaming VLANs Wlan QoS for VoIP Page Page Page Interconnecting WLANs to Cisco Campus Infrastructure Connecting APs to the Catalyst 3550 SMI or EMI Connecting APs to the Catalyst 2950 SI Connecting APs to the Catalyst 2950 EICaveats and Limitations Other Caveats and Limitations Call Admission ControlDesigning Around the Lack of Layer 3 Roaming Related Information

7920 IP specifications

The Cisco Systems 7920 IP phone represents a significant advancement in wireless communication technology, designed specifically for enterprises that require mobility and efficiency in their communication systems. This versatile device integrates seamlessly into a Cisco IP telephony network, allowing users to maintain connectivity while on the move, which is essential in fast-paced business environments.

One of the key features of the Cisco 7920 is its robust wireless capabilities. Operating on the IEEE 802.11b/g Wi-Fi standards, it provides a reliable connection to corporate networks, ensuring that users can access voice, data, and video services without being tethered to a desk. The phone supports dynamic call handling and features a responsive LCD display that enhances user interaction, making it easier to navigate menus and manage calls.

The Cisco 7920 also offers exceptional sound quality, thanks to its advanced audio technology. With Wideband audio support, users can experience clarity in conversations, which is particularly important in environments where clear communication is vital. The phone is equipped with noise-canceling capabilities that reduce background noise, allowing users to focus on their conversations without distractions.

Security is another critical aspect of the Cisco 7920. The device supports several security protocols, including WPA and WPA2, ensuring that all communications are encrypted and secure. This is crucial for organizations that handle sensitive information and need to comply with industry regulations.

Additionally, the Cisco 7920 features an extended battery life, enabling users to make calls throughout the day without frequent recharging. Its lightweight design and ergonomic build make it comfortable to use for extended periods.

In terms of integration, the Cisco 7920 IP phone is compatible with various Cisco Unified Communications Manager software versions, allowing for easy configuration and management within existing network infrastructures. Its support for multiple languages also makes it a suitable choice for international organizations, accommodating diverse user groups.

Overall, the Cisco Systems 7920 IP phone combines the necessary features, technologies, and characteristics to meet the demands of modern enterprise communication. Its blend of wireless capability, superior audio quality, security measures, and integration versatility makes it an excellent choice for organizations seeking efficient and reliable communication solutions.
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