Multicast to unicast conversion technique

• US 9,565,125 B2
• Filed: 03/11/2015
• Issued: 02/07/2017
• Est. Priority Date: 06/14/2012
• Status: Active Grant

• Current Assignee: Extreme Networks, Inc.
• Original Assignee: Aerohive Networks Incorporated (Extreme Networks, Inc.)
• Inventors: Liu, Liwu, Zeng, Jianlin
• Primary Examiner(s): LO, DIANE LEE
• Application Number:
  US14/645,184
• Publication Number:
  US 20150188836A1
• Time in Patent Office: 699 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H04L 12/18 for broadcast or conference , e.g. multicast
• CPC Class Codes: H04L 12/1881 with schedule organisation, e.g. priority, sequence management
• CPC Class Codes: H04L 12/1886 with traffic restrictions for efficiency improvement, e.g. involving subnets or subdomains
• CPC Class Codes: H04L 47/15 in relation to multipoint traffic arrangements for broadcast or multicast in data networks H04L12/18
• CPC Class Codes: H04L 47/215 using token-bucket
• CPC Class Codes: H04L 47/30 in combination with information about buffer occupancy at either end or at transit nodes
• CPC Class Codes: H04L 47/32 by discarding or delaying data units, e.g. packets or frames
• CPC Class Codes: H04L 47/527 Quantum based scheduling, e.g. credit or deficit based scheduling or token bank
• CPC Class Codes: H04L 47/621 Individual queue per connection or flow, e.g. per VC
• CPC Class Codes: H04L 47/6215 Individual queue per QOS, rate or priority
• CPC Class Codes: H04L 47/629 Ensuring fair share of resources, e.g. weighted fair queuing [WFQ]
• CPC Class Codes: H04L 47/6295 using multiple queues, one for each individual QoS, connection, flow or priority
• CPC Class Codes: H04L 49/201 Multicast operation; Broadcast operation
• CPC Class Codes: H04L 65/611 for multicast or broadcast systems for broadcast or conference H04L12/18; arrangements for broadcast or distribution combined with broadcast H04H20/00; arrangements for broadcast applications with a direct linkage to broadcast information or to broadcast space-time H04H60/00; selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS], H04W4/06
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04L 69/08 Protocols for interworking; Protocol conversion
• CPC Class Codes: H04W 28/0268 using specific QoS parameters for wireless networks, e.g. QoS class identifier [QCI] or guaranteed bit rate [GBR] negotiating SLA or negotiating QoS H04W28/24
• CPC Class Codes: H04W 28/14 using intermediate storage
• CPC Class Codes: H04W 4/06 Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services

Abstract

A technique allows stations to utilize an equal share of resources (e.g., airtime or throughput). This prevents slow stations from consuming too many resources (e.g., using up too much air time). Fairness is ensured by selective dropping after a multicast packet is converted to unicast. This prevents slow stations from using more than their share of buffer resources. Multicast conversion aware back-pressure into the network layer can be used to prevent unnecessary dropping of packets after multicast to unicast (1:n) conversion by considering duplicated transmit buffers. This technique helps achieve airtime/resource fairness among stations.

Claims

1. A method comprising:

identifying a subplurality of traffic identifier (TID) queues associated with a multicast packet;

converting the multicast packet into a multicast-to-unicast converted unicast packet for the subplurality of TID queues;

enqueueing the multicast-to-unicast converted unicast packet in available TID queues of the subplurality of TID queues, wherein availability of the subplurality of TID queues is based on an amount of unused space in each TID queue of the subplurality of TID queues;

dequeueing the multicast-to-unicast converted unicast packet from a TID queue of the available TID queues according to a token bucket checking cycle applied to the subplurality of TID queues;

transmitting the multicast-to-unicast converted unicast packet to a destination.

2. The method of claim 1, wherein dequeueing the multicast-to-unicast converted unicast packet from the TID queue of the available TID queues according to a token bucket checking cycle further comprises:

determining whether a token weight of the TID queue is greater than a token balance threshold of the TID queue;

determining whether to dequeue the multicast-to-unicast converted unicast packet from the TID queue based on the determination whether the token weight of the TID queue is greater than the token balance threshold of the TID queue.

3. The method of claim 2, wherein if it is determined that the token weight of the TID queue is greater than the token balance threshold of the TID queue, the method further comprises dequeueing the multicast-to-unicast converted unicast packet from the TID queue.

4. The method of claim 2, wherein if it is determined that the token weight of the TID queue is less than the token balance threshold of the TID queue, the method further comprises incrementing token buckets associated with the subplurality of TID queues.

5. The method of claim 1, wherein a token bucket associated with the TID queue has a token weight greater than token weights of token buckets associated with the subplurality of TID queues.

6. The method of claim 1, wherein the TID queue has a lowest estimated transmission cost of the subplurality of TID queues.

7. The method of claim 6, wherein estimated transmission costs of the subplurality of TID queues is determined based on an estimated airtime of transmitting packets in the subplurality of TID queues.

8. The method of claim 7, wherein the estimated airtime of transmitting packets in the subplurality of TID queues is determined based on airtime required to transmit previous packets to a same client.

9. The method of claim 7, wherein the estimated airtime of transmitting packets in the subplurality of TID queues is determined based on clients assigned to the same QoS profile associated with the packets.

10. The method of claim 7, wherein the estimated airtime of transmitting packets in the subplurality of TID queues is determined based on clients assigned to the same QoS profile associated with the packets and a size of the packets.

11. A system comprising:

a backpressure alleviation engine configured to identify a subplurality of traffic identifier (TID) queues associated with a multicast packet;

a multicast-to-unicast conversion engine configured to convert the multicast packet into a multicast-to-unicast converted unicast packet for the subplurality of TID queues;

a TID queuing engine configured to enqueue the multicast-to-unicast converted unicast packet in available TID queues of the subplurality of TID queues, availability of the subplurality of TID queues based on an amount of unused space in each TID queue of the subplurality of TID queues;

a TID-to-Access Category (AC) scheduling engine configured to dequeue the multicast-to-unicast converted unicast packet from a TID queue of the available TID queues according to a token bucket checking cycle applied to the subplurality of TID queues;

a medium interface configured to transmit the multicast-to-unicast converted unicast packet to a destination.

12. The system of claim 11, wherein in dequeueing the multicast-to-unicast converted unicast packet from the TID queue of the available TID queues according to a token bucket checking cycle, the TID-to-AC scheduling engine is further configured to:

determine whether a token weight of the TID queue is greater than a token balance threshold of the TID queue;

determine whether to dequeue the multicast-to-unicast converted unicast packet from the TID queue based on the determination whether the token weight of the TID queue is greater than the token balance threshold of the TID queue.

13. The system of claim 12, wherein the TID-to-AC scheduling engine is further configured to dequeue the multicast-to-unicast converted unicast packet from the TID queue, if it is determined that the token weight of the TID queue is greater than the token balance threshold of the TID queue.

14. The system of claim 12, wherein the TID-to-AC scheduling engine is further configured to increment token buckets associated with the subplurality of TID queues if it is determined that the token weight of the TID queue is less than the token balance threshold of the TID queue.

15. The system of claim 11, wherein a token bucket associated with the TID queue has a token weight greater than token weights of token buckets associated with the subplurality of TID queues.

16. The system of claim 11, wherein the TID queue has a lowest estimated transmission cost of the subplurality of TID queues.

17. The system of claim 16, wherein estimated transmission costs of the subplurality of TID queues is determined based on an estimated airtime of transmitting packets in the subplurality of TID queues.

18. The system of claim 17, wherein the estimated airtime of transmitting packets in the subplurality of TID queues is determined based on airtime required to transmit previous packets to a same client.

19. The system of claim 17, wherein the estimated airtime of transmitting packets in the subplurality of TID queues is determined based on clients assigned to the same QoS profile associated with the packets.

20. The system of claim 17, wherein the estimated airtime of transmitting packets in the subplurality of TID queues is determined based on clients assigned to the same QoS profile associated with the packets and a size of the packets.

21. A system comprising:

means for identifying a subplurality of traffic identifier (TID) queues associated with a multicast packet;

means for converting the multicast packet into a multicast-to-unicast converted unicast packet for the subplurality of TID queues;

means for enqueueing the multicast-to-unicast converted unicast packet in available TID queues of the subplurality of TID queues, wherein availability of the subplurality of TID queues is based on an amount of unused space in each TID queue of the subplurality of TID queues;

means for dequeueing the multicast-to-unicast converted unicast packet from a TID queue of the available TID queues according to a token bucket checking cycle applied to the subplurality of TID queues;

means for transmitting the multicast-to-unicast converted unicast packet to a destination.