TCP Parameter Dynamic Control
draft-song-dclc-tcpdc-04

Abstract

Congestion control has been extensively studied for many years. Today, the Transmission Control Protocol (TCP) is used in a wide range of networks (LAN, WAN, data center, campus network, enterprise network, etc.) as the de facto congestion control mechanism. Despite its common usage, TCP operates in these networks with little knowledge of the underlying network or traffic characteristics. As a result, it is deemed to continuously increase or decrease its congestion window size in order to handle changes in the network or traffic conditions. Thus, TCP frequently overshoots or undershoots the ideal rate making it a "Jack of all trades, master of none" congestion control protocol. In light of the emerging popularity of centrally controlled networks such as Software-Defined Networks (SDNs), we propose a framework that takes advantage of the information available at the central controller to improve TCP. Specifically, in this document, we propose OpenTCP as a dynamic and programmable TCP adaptation framework for centrally controlled networks. OpenTCP gathers global information about the status of the network and traffic conditions through the centralized controller, and uses this information to adapt TCP. OpenTCP periodically sends updates to end-hosts which, in turn, update their behaviour using a simple kernel module. This document describes a framework and message flows for centralized congestion control parameter adaptation based on congestion control policies and network status measurements, so that each end host in a network can make better use of the network resource according to the available resources. In the rest of this document we use TCP as a standard congestion control mechanism, but the same idea can be applied to other congestion control protocols as well. A TCP Optimization Element and a TCP Optimization Agent are introduced. The message patterns include request response and subscription/notification. This mechanism can be used in network service providers' networks, as well as in data center networks.

Authors

Monia Ghobadi
Haibin Song
Rachel Huang
Yashar Ganjali

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)