This object identifies the channel index, relative to the slot and port, of the Logical Link in a Logical Link up/down trap, with a value of -1 when there is no channel involved. Administrators use it to further localize a link event on channelized interfaces, such as channelized DS3 ports, down to the specific channel. For example, a value of -1 in this field for a link-down trap tells an engineer the affected interface isn't channelized, so the port itself is the relevant unit, not a sub-channel.