Multicast to unicast conversion technique

• US 10,523,458 B2
• Filed: 02/12/2019
• Issued: 12/31/2019
• Est. Priority Date: 06/14/2012
• Status: Active Grant

• Current Assignee: Extreme Networks, Inc.
• Original Assignee: Extreme Networks, Inc.
• Inventors: Liu, Liwu, Zeng, Jianlin
• Primary Examiner(s): Lo, Diane L
• Application Number:
  US16/274,115
• Publication Number:
  US 20190190735A1
• Time in Patent Office: 322 Days
• Field of Search: None
• 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 system comprising:

a queuing engine configured to enqueue a multicast packet of a multicast packet stream into a multicast queue;

a multicast-to-unicast conversion engine configured to convert the multicast packet into a plurality of unicast packets for transmission to a plurality of stations;

a buffer fairness enforcement engine configured to allocate buffer resources for a station of the plurality of stations based on available buffer resources, wherein, in operation, the buffer fairness enforcement engine allocates an initial amount of buffer resources to the station and increases the initial amount of buffer resources for the station in accordance with a maximum of buffer resources that can be allocated to the station;

a transfer ID (TID) queuing engine configured to enqueue the plurality of unicast packets into a plurality of TID queues;

a scheduling engine configured to dequeue one or more unicast packets from the plurality of TID queues for transmission to one or more stations of the plurality of stations;

an interface for transmitting the one or more unicast packets to the one or more stations of the plurality of stations.

2. The system of claim 1, wherein an amount of current available buffer resources divided by an amount of total available buffer resources has a lower limit of 0.02.

3. The system of claim 1, wherein if an amount of current available buffer resources divided by an amount of total available buffer resources is greater than 0.08, the buffer fairness enforcement engine allocates an unlimited amount of buffer resources to each station of the plurality of stations.

4. The system of claim 1, wherein the initial amount of buffer resources is calculated by dividing an amount of total available buffer resources by a number of active stations of the plurality of stations.

5. The system of claim 1, wherein the buffer fairness enforcement engine is further configured to increase the initial amount of buffer resources for a particular station of the plurality of stations in accordance with the equation M=C*A/S, where

M is the maximum of buffer resources that can be allocated to the particular station;

C is a constant;

A is an amount of current available buffer resources;

S is a number of active stations of the plurality of stations.

6. The system of claim 1, wherein the buffer fairness enforcement engine is further configured to increase the initial amount of buffer resources for a particular station of the plurality of stations in accordance with the equation M=V*A/S, where

M is the maximum of buffer resources that can be allocated to the particular station;

V is a variable determined based on current traffic or predicted traffic;

A is an amount of total available buffer resources;

S is a number of active stations of the plurality of stations.

7. The system of claim 1, wherein the maximum of buffer resources that can be allocated to a particular station is determined by dividing the amount of current available buffer resources by an amount of total available buffer resources and rounding to a nearest value.

8. The system of claim 1, further comprising a classification and queuing engine that includes the queuing engine, wherein the classification and queuing engine assigns a quality of service (QoS) profile to the multicast packet.

9. The system of claim 8, wherein the buffer fairness enforcement engine is further configured to increase the initial amount of buffer resources for a particular station of the plurality of stations in accordance with the equation M=V*A/S, where

M is the maximum of buffer resources that can be allocated to the particular station;

V is a variable determined based on the QoS profile assigned to the multicast packet;

A is an amount of total available buffer resources;

S is a number of active stations of the plurality of stations.

10. A method comprising:

enqueuing a multicast packet of a multicast packet stream into a multicast queue;

converting the multicast packet into a plurality of unicast packets for transmission to a plurality of stations;

allocating buffer resources for a station of the plurality of stations based on available buffer resources, including;

allocating an initial amount of buffer resources to the station; and

increasing the initial amount of buffer resources for the station in accordance with a maximum of buffer resources that can be allocated to the station;

enqueuing the plurality of unicast packets into a plurality of transfer ID (TID) queues;

dequeuing one or more unicast packets from the plurality of TID queues for transmission to one or more stations of the plurality of stations;

transmitting the one or more unicast packets to the one or more stations of the plurality of stations.

11. The method of claim 10, wherein an amount of current available buffer resources divided by an amount of total available buffer resources has a lower limit of 0.02.

12. The method of claim 10, wherein if an amount of current available buffer resources divided by an amount of total available buffer resources is greater than 0.08, the method further comprises allocating an unlimited amount of buffer resources to each station of the plurality of stations.

13. The method of claim 10, further comprising calculating the initial amount of buffer resources by dividing an amount of total available buffer resources by a number of active stations of the plurality of stations.

14. The method of claim 10, further comprising increasing the initial amount of buffer resources for a particular station of the plurality of stations in accordance with the equation M=C*A/S, where

M is the maximum of buffer resources that can be allocated to the particular station;

C is a constant;

A is an amount of current available buffer resources;

S is a number of active stations of the plurality of stations.

15. The method of claim 10, further comprising increasing the initial amount of buffer resources for a particular station of the plurality of stations in accordance with the equation M=V*A/S, where

M is the maximum of buffer resources that can be allocated to the particular station;

V is a variable determined based on current traffic or predicted traffic;

A is an amount of total available buffer resources;

S is a number of active stations of the plurality of stations.

16. The method of claim 10, further comprising determining the maximum of buffer resources that can be allocated to the particular station by dividing the amount of current available buffer resources by an amount of total available buffer resources and rounding to a nearest value.

17. The method of claim 10, further comprising assigning a quality of service (QoS) profile to the multicast packet.

18. The method of claim 17, further comprising increasing the initial amount of buffer resources for a particular station of the plurality of stations in accordance with the equation M=V*A/S, where

M is the maximum of buffer resources that can be allocated to the particular station;

V is a variable determined based on the QoS profile assigned to the multicast packet;

A is an amount of total available buffer resources;

S is a number of active stations of the plurality of stations.

19. A system comprising:

means for enqueuing a multicast packet of a multicast packet stream into a multicast queue;

means for converting the multicast packet into a plurality of unicast packets for transmission to a plurality of stations;

means for allocating buffer resources for a station of the plurality of stations based on available buffer resources, including;

means for allocating an initial amount of buffer resources to the station; and

means for increasing the initial amount of buffer resources for the station in accordance with a maximum of buffer resources that can be allocated to the station;

means for enqueuing the plurality of unicast packets into a plurality of transfer ID (TID) queues;

means for dequeuing one or more unicast packets from the plurality of TID queues for transmission to one or more stations of the plurality of stations;

means for transmitting the one or more unicast packets to the one or more stations of the plurality of stations.