QoS shaping/provisioning for data communication switch
A method and apparatus provides QoS shaping/provisioning scheme for a data communications switch, such as a DiffServ aware router or a 802.1Q aware bridge, in which distinct internal and outbound priority values are assigned to a packet based on flow properties associated with an inbound packet. The flow properties used to assign the internal and outbound priority values may include at least one value from a packet field that is not dedicated to defining QoS. The internal priority value provides a priority to the packet during processing in the switch. The outbound priority value is applied to the packet in lieu of the inbound priority value prior to transmitting the packet from the switch. The flow properties used to determine the internal and outbound priority values may include, for example, Layer 2, Layer 3, and Layer 4 information encoded in the packet.
1. A quality of service (QoS) provisioning method for a data communication switch having a plurality of ports, comprising:
receiving a packet on a first port of the switch;
mapping information from the packet to a priority descriptor;
selecting an internal priority value and an outbound priority value using the priority descriptor, wherein the internal priority value and the outbound priority value are different;
prioritizing the packet while on the switch using the internal priority value;
appending the packet with the outbound priority value; and
transmitting the appended packet on a second port of the switch.
2. The method of claim 1 , wherein the internal priority value is used to select a forwarding queue on the switch for the packet.
3. The method of claim 1 , wherein the outbound priority value is appended to the packet in an 802.1Q tag field.
4. The method of claim 1 , wherein the internal priority value has a smaller bit count than the priority descriptor.
5. The method of claim 1 , wherein the outbound priority value has a smaller bit count than the priority descriptor.
6. The method of claim 5 , wherein the priority descriptor is a six-bit value and the outbound priority value is a three-bit value.
7. The method of claim 1 , wherein the information from the packet is selected from one or more Layer 2 or Layer 3 fields.
8. The method of claim 7 , wherein at least one of the Layer 2 or Layer 3 fields is not dedicated to defining QoS.
9. A quality of service (QoS) provisioning method for a data communication switch having a plurality of ports, comprising:
receiving a packet having a plurality of inbound priority values on a first port of the switch;
determining an internal priority value and an outbound priority value using a selected one of the inbound priority values, wherein the internal priority value and the outbound priority value are different;
prioritizing the packet while on the switch using the internal priority value;
appending the packet with the outbound priority value; and
transmitting the appended packet on a second port of the switch.
10. The method of claim 9 , wherein the internal priority value is used to select a forwarding queue on the switch for the packet.
11. The method of claim 9 , wherein the outbound priority value is appended to the packet in an 802.1Q tag field.
12. A quality of service (QoS) provisioning method for a data communication switch having a plurality of ports, comprising:
receiving a packet having an inbound priority value on a first port of the switch;
mapping information from the packet to a priority descriptor;
determining a first prioritization for the packet while on the switch using the inbound priority value and the priority descriptor; and
determining a second prioritization for the packet as transmitted from the switch using at least the priority descriptor appending the packet with the outbound priority value; and transmitting the appended packet on a second port of the switch.
13. The method of claim 12 , wherein the step of determining the first prioritization includes determining a forwarding queue on the switch for the packet.
14. The method of claim 12 , wherein step of determining the second prioritization includes determining an outbound priority value for appending to the packet as transmitted from the switch.
15. The method of claim 14 , wherein the outbound priority value is appended to the packet in an 802.1Q tag field.
16. The method of claim 12 , wherein the step of determining the second prioritization includes using the inbound priority value.
17. The method of claim 12 , wherein the information from the packet is selected from one or more Layer 2 or Layer 3 fields.
18. The method of claim 17 , wherein at least one of the Layer 2 or Layer 3 fields is not dedicated to defining QoS.