A method, comprising: at a server system: prioritizing transmission of data in a managed network, characterized in that the method comprises: assigning a group of user sessions to a single modulator, wherein the user sessions comprise data in a plurality of classes, each class having a respective priority, wherein the plurality of classes includes, in order of priority from highest priority to lowest priority, transport control information, audio data, video data, user-interface graphical elements, and error-correction information; computing an aggregate bandwidth of the group of user sessions for a first frame time; determining that the aggregate bandwidth for the first frame time exceeds a specified budget for the modulator; in response to determining that the aggregate bandwidth for the first frame time exceeds the specified budget, allocating bandwidth for bits of the data comprised by the group of user sessions during the first frame time in accordance with the class priorities, such that the user sessions of the group of user sessions share the allocated bandwidth, wherein bandwidth is provided for all audio data in the group of user sessions; using the modulator, multiplexing the group of user sessions onto a channel corresponding to the modulator, in accordance with the allocated bandwidth, wherein for each user session a compliant MPEG transport stream is generated from the allocated bits; and transmitting the multiplexed group of user sessions over the managed network. prioritizing transmission of data in a managed network, characterized in that the method comprises: assigning a group of user sessions to a single modulator, wherein the user sessions comprise data in a plurality of classes, each class having a respective priority, wherein the plurality of classes includes, in order of priority from highest priority to lowest priority, transport control information, audio data, video data, user-interface graphical elements, and error-correction information; computing an aggregate bandwidth of the group of user sessions for a first frame time; determining that the aggregate bandwidth for the first frame time exceeds a specified budget for the modulator; in response to determining that the aggregate bandwidth for the first frame time exceeds the specified budget, allocating bandwidth for bits of the data comprised by the group of user sessions during the first frame time in accordance with the class priorities, such that the user sessions of the group of user sessions share the allocated bandwidth, wherein bandwidth is provided for all audio data in the group of user sessions; using the modulator, multiplexing the group of user sessions onto a channel corresponding to the modulator, in accordance with the allocated bandwidth, wherein for each user session a compliant MPEG transport stream is generated from the allocated bits; and transmitting the multiplexed group of user sessions over the managed network. assigning a group of user sessions to a single modulator, wherein the user sessions comprise data in a plurality of classes, each class having a respective priority, wherein the plurality of classes includes, in order of priority from highest priority to lowest priority, transport control information, audio data, video data, user-interface graphical elements, and error-correction information; computing an aggregate bandwidth of the group of user sessions for a first frame time; determining that the aggregate bandwidth for the first frame time exceeds a specified budget for the modulator; in response to determining that the aggregate bandwidth for the first frame time exceeds the specified budget, allocating bandwidth for bits of the data comprised by the group of user sessions during the first frame time in accordance with the class priorities, such that the user sessions of the group of user sessions share the allocated bandwidth, wherein bandwidth is provided for all audio data in the group of user sessions; using the modulator, multiplexing the group of user sessions onto a channel corresponding to the modulator, in accordance with the allocated bandwidth, wherein for each user session a compliant MPEG transport stream is generated from the allocated bits; and transmitting the multiplexed group of user sessions over the managed network.