Class of Service

DOCSIS configuration files can contain a single or multiple class of service (CoS) profile that supports data-only configurations or data and voice configurations. The single CoS profile provides for best-effort delivery of data traffic; the multiple CoS profile provides for real-time delivery of voice traffic.

Using the multiple CoS profile, the first CoS is used for data traffic (or voice traffic if no other CoS is defined), and the second CoS is used for voice traffic. Real-time voice traffic is given a higher priority than lower-priority data traffic. Data traffic is fragmented to avoid interfering with the timeslots allocated for voice traffic. This allows voice traffic to be delivered in a timely manner by delaying transmission of data traffic in a way that does not degrade the overall quality of service (QoS).

The following information is entered by the user to specify the CoS class ID, maximum downstream rate, maximum upstream rate, upstream channel priority, guaranteed minimum upstream rate, maximum upstream transmit burst, and to enable BPI encryption for CoS privacy.

Class ID

Specifies the ID (1 to 16) for this class of service to which the encapsulated string applies. The default value is 1.

Example: 1

Note: For each CoS in the configuration file, you MUST include a valid class ID. If there are multiple CoS encodings in the same configuration file, no two encodings should have the same class ID. All class IDs MUST be unique.

Maximum Downstream Rate

Specifies the maximum downstream data rate (in bits/sec) allowed for traffic associated with this class of service. This is the peak data rate for Packet PDU data (including destination MAC address and the CRC) over a one-second interval. This is a limit on the modem, not a guarantee of service or that this rate is available. Cisco strongly recommends that you enter a value in this field. If no value is present, there is no maximum downstream data rate.

Example: 512000 (bps)

Maximum Upstream Rate

Specifies the maximum upstream data rate (in bits/sec) allowed for traffic associated with this class of service. This is the peak data rate for Packet PDU data (including destination MAC address and the CRC) over a one-second interval. This is a limit on the modem, not a guarantee of service or that this rate is available. Cisco strongly recommends that you enter a value in this field. If no value is present, there is no maximum upstream data rate.

Example: 128000 (bps)

Upstream Channel Priority

Specifies the priority (0 to 7, where 7 is highest priority) assigned to this class of service for data transmission in the upstream channel.

Example: 1

Guaranteed Minimum Upstream Rate

Specifies the minimum upstream data rate (in bits/sec) that is guaranteed for traffic associated with this class of service. The default value is 0, indicating that there is no guaranteed minimum upstream data rate.

Example: 0 (bps)

Maximum Upstream Transmit Burst

Specifies the maximum size of burst traffic to be allowed on this upstream channel. The size is specified in bytes, 0 to 65335, where 0 is no limit. If this field is set to a non-zero value, it should be set to at least 1600 so that it is greater than the maximum Ethernet frame size of 1518 plus the associated packet overhead.

Example: 1600 (bytes)

Note: The recommended maximum upstream transmit burst rate is 1600 bytes. This provides maximum compatibility with DOCSIS 1.0 modems and VoIP. Using a value of 0 allows the modem to concatenate multiple packets into an 8000 byte or longer packet. This could produce severe voice jitter and/or dropped calls.

Baseline Privacy Enable

Specifies whether BPI encryption should be enabled on traffic associated with this class of service:

To enable BPI encryption (1)
To disable BPI encryption (0)

The default value is 0.