Support: All
    Default: 1492          Value: 128-65535

    Preferred maximum data-link block size, in octets. You can modify
    this characteristic only when the entity is disabled. If the
    characteristic type is csma-cd, this characteristic is a read-
    only attribute whose value is fixed at 1492.

    set [node node-id] routing circuit circuit-name -
        manual data link sdu size

    Example:

    set routing circuit fddi-1 manual data link sdu size 4352