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Uniform Weighted Round Robin Arbitration for Packet Switch Interconnect Network

IP.com Disclosure Number: IPCOM000009806D
Publication Date: 2002-Sep-19
Document File: 3 page(s) / 61K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that uses an algorithm to generate an optimized Uniform Weighted Round Robin (UWRR) table that is important for the Quality of Service (QoS) support (including isochronous support) in interconnect techniques such as PCI Express. Benefits include minimizing congestion over small and large networks.

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Uniform Weighted Round Robin Arbitration for Packet Switch Interconnect Network

Disclosed is a method that uses an algorithm to generate an optimized Uniform Weighted Round Robin (UWRR) table that is important for the Quality of Service (QoS) support (including isochronous support) in interconnect techniques such as PCI Express. Benefits include minimizing congestion over small and large networks.

Background

The traditional Weighted Round Robin (WRR) algorithm achieves fair arbitration by assigning a weight to each client (it can be a labeled stream or a port within a switch/hub, or a group of streams belonging to the same service level), which corresponds to the pre-assigned bandwidth allocation for the client. The sum of weights for all clients forms a WRR cycle. The arbiter provides services for a client proportional to the assigned weight. When the amount of service reaches the weight value, or when there are no outstanding requests from the client, the arbiter turns to serve the next client in the list.

This WRR arbitration process provides fair services for the clients. However, it contains two major drawbacks:

·        Large buffer. Larger buffers are required in the server (switch or any network components). In particular, the minimal buffer for each client is up to one WRR cycle time.

·        Large jitter. Large jitter is introduced when the server services one client continuously before turning its attention to next client. Therefore, traffic for each client experiences alternating busy and idle cycles. Without further traffic regulation, these cycles accumulate at each stage in the network.

General Description

Giv...