The Cisco IOS Release 12.2(33)SCF introduces the Automatic ROMMON Upgrade feature, which enables the cable interface line cards (CLCs) to automatically upgrade the ROMMON image whenever a newer version is available.
The ROMMON is a bootstrap program that initializes the hardware and boots up the Cisco IOS software when the Cisco CMTS (or CLC) is powered on or rebooted. It is an integral part of the CLC firmware, which provides basic services such as CPU initialization, memory mapping, and image relocation.
Two types of ROMMON images exist on CLCs:
Primary ROMMON image—This is the original image shipped with the system. This is a read-only image that cannot be erased or altered in the field. In case the secondary ROMMON image gets corrupted during upgrade, the primary ROMMON image is used to boot up the CLC.
Secondary ROMMON image—This is a field upgradeable image which has the latest software version. This image is upgraded by the Automatic ROMMON Upgrade feature.
The ROMMON image may require updates due to feature additions or enhancements. The Automatic ROMMON Upgrade feature enables the CLC to upgrade the secondary ROMMON image without user intervention. The user is informed about the upgrade status through error or warning messages. For more information on the upgrade status, see Verifying Automatic ROMMON Upgrade on a Cable Interface Line Card.
Automatic upgrade of the secondary ROMMON image is performed only when the new image version is higher than the current secondary ROMMON image version. For example, if the secondary ROMMON image version is 160, then the ROMMON image upgrade will be performed only if the new image version is 161 or above.
New ROMMON versions are backward compatible. The updated ROMMON image can be used with the older Cisco IOS Release versions. If, for any reasons, older ROMMON version needs to be used, it is possible to downgrade the ROMMON image using the Automatic ROMMON Upgrade feature with few configuration changes.
To downgrade the ROMMON image, the following conditions must be met:
The updated ROMMON image may contain critical bug fixes and feature enhancements. It is recommended that the ROMMON image is not downgraded, unless it is necessary.
By default, the automatic ROMMON image upgrade and downgrade are disabled for all CLCs. Use the cable linecard auto-rommon-upgrade command to configure automatic ROMMON image upgrade on CLCs. Use cable linecard auto-rommon-downgrade command to configure automatic ROMMON image downgrade on CLCs.
Effective with Cisco IOS Release 12.2(33)SCF1, the automatic ROMMON image upgrade is enabled by default.