# US 2013/0155853 A1 · Hierarchical occupancy-based congestion management

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- Number: US 2013/0155853 A1
- Document ID: US20130155853A1
- Status: Published application
- Kind: A1
- Application number: 13/608,120
- Filed: 2012-09-10
- Published: 2013-06-20
- Earliest claimed: 2011-12-19
- Assignees: International Business Machines Corporation
- Inventors: Yiyu L. Chen; Nikolaos I. Chrysos; Rolf Clauberg; Mircea R. Gusat; Cyriel J. Minkenberg; Fredy D. Neeser; Kenneth M. Valk
- Web page: https://patentgrep.com/patent/US20130155853A1

## CPC

- H04L 47/10: Flow control; Congestion control
- H04L 47/30: in combination with information about buffer occupancy at either end or at transit nodes
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A system for hierarchical occupancy based congestion management includes a buffer embodied in a computer readable storage medium including a plurality of buffer units for storing packets of a data flow received from sources. The system includes a buffer manager that stores information about the packets stored in the buffer, including a selection criterion associated with each of the plurality of sources and a congestion estimator that monitors a congestion level in the buffer. The system also includes a occupancy sampler that randomly selects at least two occupied buffer units from the plurality of buffer units and identifies the source of the packet stored in each of the occupied buffer units and a congestion notification message generator that generates a congestion notification message; wherein if the congestion level in the buffer exceeds a threshold value the congestion notification message is sent to the identified source with a higher selection criteria.

## Claims

### Claim 1

A system for hierarchical occupancy based congestion management comprising:
a buffer embodied in a computer readable storage medium comprising a plurality of buffer units for storing packets of a data flow received from one or more sources;
a buffer manager that stores information about the packets stored in the buffer, including a selection criterion associated with each of the sources;
a congestion estimator that monitors a congestion level in the buffer;
a occupancy sampler that randomly selects at least two occupied buffer units from the plurality of buffer units and identifies the source of the packet stored in each of the occupied buffer units; and
a congestion notification message generator that generates a congestion notification message; wherein if the congestion level in the buffer exceeds a threshold value the congestion notification message is sent to the identified source with a higher selection criteria.

### Claim 2 (depends on 1)

The system of claim 1, wherein the selection criterion is a congestion level of a downstream link in a path of the data flow.

### Claim 3 (depends on 1)

The system of claim 1, wherein the selection criterion is an occupancy percentage of the buffer associated with the data flow.

### Claim 4 (depends on 1)

The system of claim 1, wherein the selection criterion is an averaged congestion level of a plurality of downstream links in a path of the data flow.

### Claim 5 (depends on 1)

The system of claim 1, wherein the congestion notification message instructs the source to reduce its data transmission rate.

### Claim 6 (depends on 1)

The system of claim 1, wherein determining if the buffer is congested is triggered by an arrival of data packet at the buffer.

### Claim 7 (depends on 1)

The system of claim 1, wherein determining if the buffer is congested is done on a periodic basis.