Method and equipment for performing flow shaping that maintains service quality in packet-switched telecommunications
The invention relates to a method and equipment for performing flow shaping that maintains service quality in packet-switched telecommunications. Using the method according to the invention, the speed properties (OR, PIR, CBS) of an aggregate flow (A) can be monitored and limited in a situation, in which the aggregate flow contains delay-critical traffic (V 1 ), the forwarding of packets representing which cannot be delayed. The invention is based on the fact that, when forwarding packets representing the aggregate flow, a variable is updated, the value of which expresses the earliest permitted moment, at which a packet, representing traffic (V 2 ) other than the delay-critical traffic, can be forwarded. In that case, the transfer speed of the traffic (V 2 ) other than delay-critical traffic adapts to the variations in the transfer speed of the delay-critical traffic, allowing the speed properties of the aggregate flow to be monitored and limited.
1. A method comprising:
updating a variable as a result of forwarding a packet representing a first traffic flow and a packet representing a second traffic flow, the first and second traffic flows being separate traffic flows and said variable indicating an earliest permitted moment a next packet is allowed to be forwarded without violating at least one transmission speed limitation related to flow shaping; and
forwarding the next packet independently of said variable if the next packet represents the first traffic flow, allowing the next packet to be forwarded earlier than the earliest permitted moment and forwarding the next packet not earlier than the earliest permitted moment if the next packet represents said second traffic flow.
2. The method according to claim 1 , wherein the earliest permitted moment for forwarding the packet representing the second traffic flow is defined solely on the basis of said variable.
3. The method according to claim 1 wherein a Valid Time to Send (VTS) value is used as said variable.
4. The method according to claim 3 , wherein the updating said variable comprises updating the VTS value on the basis of maximum permitted burst size and maximum permitted mean transmission speed related to the flow shaping of the aggregate of the first and second traffic flows.
5. The method according to claim 1 , further including forwarding packets representing the first traffic flow at a higher priority (Strict Priority) than packets representing the second traffic flow.
6. The method according to claim 1 , wherein packets carry digital information, the digital information is transferred as constant or variable-length packets.
7. The method according to claim 1 , further comprising forwarding the packets representing the first and second traffic flows along a plurality of transfer links.
8. The method according to claim 1 , further comprising multiplexing the first and second traffic flows on the basis of Weighted Fair Queuing (WFQ).
9. An equipment including:
a queue configured to receive packets;
a classifier configured to classify a packet arriving in the equipment as representing one of a first traffic flow and a second traffic flow, the first and second traffic flows being separate traffic flows;
a shaper configured to (i) update a variable as a result of forwarding packets representing the first traffic flow to one or more outgoing links and as a result of forwarding packets representing the second traffic flow to the one or more outgoing links, said variable indicating after each forwarding the earliest permitted moment when a next packet can be forwarded without violating transmission speed limitations related to flow shaping of an aggregate of the first and second traffic flows, and (ii) define, on the basis of said variable, the earliest permitted moment; and
a transfer unit configured to forward the next packet independently of said variable if the next packet represents the first traffic flow, allowing the next packet to be forwarded earlier than the earliest permitted moment, and configured to forward the next packet not earlier than the earliest permitted moment if the next packet represents said second traffic flow.
10. The equipment according to claim 9 , wherein the shaper is further configured to define the earliest permitted moment of forwarding the packet representing the second traffic flow solely on the basis of said variable.
11. The equipment according to claim 9 , wherein the shaper is configured to use a Valid Time to Send (VTS) value as said variable.
12. The equipment according to claim 11 , wherein the shaper is further configured to update the VTS value on the basis of maximum permitted burst size and maximum permitted mean transmission speed related to the flow shaping of the aggregate of the first and second traffic flows.
13. The equipment according to claim 9 , wherein the equipment includes a multiplexer configured to schedule packets representing the first traffic flow to be forwarded at a higher priority (Strict Priority) than packets representing the second traffic flow.
14. The equipment according to claim 9 , wherein the queue for receiving packets is configured to receive constant or variable-length packets.
15. The equipment according to claim 9 , wherein the transfer unit is configured to forward the packets representing the first and second traffic flows along a plurality of transfer links.
16. The equipment according to claim 9 , further comprising a multiplexer configured to multiplex the first and second traffic flows on the basis of Weighted Fair Queuing (WFQ).
17. A method comprising:
forwarding packets representing an aggregate flow, the aggregate flow including a delay-critical first traffic flow and a non-delay-critical second traffic flow, the first and second traffic flows being separate traffic flows; and
updating a variable as a result of the forwarding of packets representing the aggregate flow, a value of said variable representing the earliest moment a next packet representing the aggregate flow is allowed to be forwarded without violating transmission speed limitations related to flow shaping of the aggregate flow, forwarding the next packet independently of said variable if the next packet represents the delay-critical first traffic flow, allowing the next packet to be forwarded earlier than the earliest permitted moment, and forwarding the next packet not earlier than the earliest permitted moment, if the next packet represents the non-delay-critical second traffic flow.
18. The method according to claim 17 , wherein transmission speed of the non-delay-critical second traffic flow adapts to variations in transmission speed of the delay-critical first traffic flow so that speed properties of the aggregate flow are controlled without delaying the forwarding of the delay-critical first traffic flow.
19. The method according to claim 17 , further comprising updating said variable on the basis of maximum permitted burst size and maximum permitted mean transmission speed related to the flow shaping of the aggregate flow.
20. An equipment comprising:
a transfer unit configured to forward packets representing an aggregate flow, the aggregate flow including a delay-critical first traffic flow and a non-delay-critical second traffic flow, the first and second traffic flows being separate traffic flows; and
a shaper configured to update a variable as a result of forwarding the packets representing the aggregate flow, a value of said variable representing the earliest moment a next packet representing the aggregate flow is allowed to be forwarded without violating transmission speed limitations related to flow shaping of the aggregate flow, the transfer unit further configured to forward the next packet independently of said variable if the next packet represents the delay-critical first traffic flow, allowing the next packet to be forwarded earlier than the earliest permitted moment, and to forward the next packet not earlier than the earliest moment represented by said variable if the next packet represents said non-delay-critical second traffic flow.
21. The equipment according to claim 20 , wherein the shaper is further configured to cause transmission speed of the non-delay-critical second traffic flow to adapt to variations in transmission speed of the delay-critical first traffic flow so that speed properties of the aggregate flow are controllable without delaying forwarding of the delay-critical first traffic flow.
22. The equipment according to claim 20 , wherein the shaper is further configured to update said variable on the basis of maximum permitted burst size and maximum permitted mean transmission speed related to the flow shaping of the aggregate flow.