The trafficGroupMembership object allows the user to add and delete physical ports from traffic groups. Because a physical port can only belong to one traffic group, the last assignment of a physical port to a traffic group will determine the traffic group in which the physical port is a member. There is a default traffic group which physical ports belong to until management changes the assignments of physical ports to traffic groups. If a physical port is removed from a traffic group, it is placed back into the default traffic group. The default traffic group can not be modified directly. It changes when new traffic groups are added or removed from other traffic groups. The default traffic group is traffic group 1. The trafficGroupMembership is expressed using a shorthand that specifies which physical ports belong in the traffic group. An example of a specification would be : (1,6-9,21) where commas separate physical ports and hyphens are short- hand for specifying a range of numbers. This example would assign physical ports 1,6,7,8,9, and 21 to the specified traffic group. Physical port numbers are specified in decimal. A traffic group will read back in a form equivalent to the form written. It may not read back exactly as written.