FLOW DISTRIBUTION ALGORITHM FOR AGGREGATED LINKS IN AN ETHERNET SWITCH

• US 20140173129A1
• Filed: 01/11/2013
• Published: 06/19/2014
• Est. Priority Date: 12/18/2012
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Vaidhyanathan, Natarajan, Verrilli, Colin B., Walk, Bruce M., Wind, Daniel, BASSO, Claude
• Granted Patent: US 9,231,781 B2
• Time in Patent Office: Days
• US Class Current: 709/238
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: H04L 45/245 Link aggregation, e.g. trunking
• CPC Class Codes: H04L 45/7453 using hashing
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

Link aggregation is a practice that uses multiple Ethernet links between two end points in order to obtain higher bandwidth and resiliency than possible with a single link. A flow distribution technique is provided to distribute traffic between the two end points equally across all links in the group and achieve greater efficiency. The flow distribution technique generates and sub-divides a hash value based on received packet flow. The divided portions of the hash value are used in a hierarchical fashion to select a link to use for this packet.

Claims

1. A method for forwarding a data frame through a distributed network switch, the method comprising:

generating a hash value based on routing information of a data frame;

dividing the hash value into a plurality of chunks, wherein values of the plurality of chunks correspond to a plurality of links associated with a link aggregation group;

determining a selected link having an up state from the plurality of links based on a hierarchical order of the plurality of chunks; and

forwarding the data frame to the selected link.

2. The method of claim 1, wherein the dividing the hash value into a plurality of chunks further comprises modifying each of the plurality of chunks based on a number of the plurality of links.

3. The method of claim 2, wherein modifying a chunk further comprises reducing a most significant bit of the chunk based on the number of the plurality of links.

4. The method of claim 1, wherein the determining the selected link having an up state based on the hierarchical order of the plurality of chunks further comprises:

responsive to determining a first chunk of the plurality of chunks is within range of a number of the plurality of links and the first chunk corresponds to a first link having an up state, selecting the first link.

5. The method of claim 4, further comprising:

responsive to determining the first chunk of the plurality of chunks is not within range of a number of the plurality of links or the first chunk does not correspond to a link having an up state, determining a second chunk of the plurality of chunks is within range of the number of the plurality of links and the second chunk corresponds to a second link having an up state; and

selecting the second link.

6. The method of claim 4, further comprising:

determining the first chunk of the plurality of chunks is not within range of a number of the plurality of links or the first chunk does not correspond to a link having an up state;

modifying a second chunk of the plurality of chunks to be within range of the number of the plurality of links; and

responsive to determining the second chunk corresponds to a second link having an up state, selecting the second link.

7. The method of claim 1, wherein the determining the selected link having an up state based on the hierarchical order of the plurality of chunks further comprises:

responsive to determining none of the plurality of chunks are within range of a number of the plurality of links and are corresponding to a link having an up state, selecting a first available link relative to a down link corresponding to a first chunk of the plurality of chunks.

8. The method of claim 7, wherein the selecting the first available link further comprises:

generating a rotated link state pattern based on link state information of the plurality of links and based on the first chunk; and

selecting the first available link based on the generated rotated link state pattern.