You are upgrading the firmware on all Cisco IP Phone 7961s that are connected to your company’s network.
Which of the following upgrade methods is most likely to require high bandwidth?
- individual IP phone upgrades
- load server download
- peer firmware sharing
- traditional TFTP server download
Of the available choices, the traditional Trivial File Transfer Protocol (TFTP) server download method of IP phone firmware upgrade is most likely to require high bandwidth. When using the traditional TFTP server download method, each IP phone independently downloads the new image from the TFTP server in an “every man for himself” style strategy. When firmware images were small, this strategy was acceptable even when the IP phones were on a network at a separate location from Cisco Unified Communications Manager (UCM). Over time, IP phone firmware sizes have increased, which could cause slow upgrades over WAN links. In addition, the traditional TFTP download method could create high CPU usage on the UCM TFTP server.
You can also update the firmware on an individual IP phone by using the traditional TFTP method. First, you should make a note of the existing Phone Load Name value for the phone model that you want to upgrade by navigating to Device > Device Settings > Device Defaults in UCM Administrator. This is important because installing the new firmware image will automatically overwrite the value of the Phone Load Name field in Device > Device Settings > Device Defaults. You should then upload the new firmware to UCM by navigating to Software Upgrades > Install/Upgrade.
After you upload the new firmware, specify the name of the new firmware in the Phone Load Name field for the specific IP phone you want to upgrade by using UCM Administration’s Device > Phone menu. Next, navigate to Device > Device Settings > Device Defaults and replace the new value of the Phone Load Name field with its original value. This will prevent other IP phones from downloading the new firmware after you restart the TFTP service.
Finally, you should restart the TFTP service in Cisco Unified Serviceability. After the service restarts, the IP phone you edited in UCM Administration should download the new firmware, upgrade the firmware, and restart. Other IP phones might restart as well. However, those IP phones will not be upgraded.
In contrast to the traditional TFTP server method, the load server download method enables the administrator of the LAN on which the IP phone operates to provide his or her own local TFTP server for firmware upgrades instead of relying on a remotely located default UCM TFTP server. This means that IP phones on remote networks will be able to download firmware updates in approximately the same amount of time it would take for an IP phone that is local to UCM. In addition, the TFTP load can be balanced among multiple TFTP servers at multiple sites. One disadvantage to the load server download method is that the local administrator is responsible for copying the firmware update to the TFTP server. Therefore, the TFTP upload and server configuration is subject to human error.
Peer firmware sharing is a method of updating the firmware on Cisco IP phones. When peer firmware sharing is implemented, only one Cisco IP phone at a location is responsible for downloading the new firmware. The firmware is then distributed to the other IP phones on the LAN in a parent-child hierarchy. The downloading phone distributes the firmware to its children. Those children then distribute the firmware to their children, and so on. No one parent in the hierarchy can have more than two children. Some disadvantages to the peer firmware sharing method are that the hierarchies are limited to their own subnets and are specific to phone model. In addition, peer firmware sharing must be enabled on each IP phone.