Abstract

This document outlines the performance impact of HP-UX IPQoS on an HP-UX system. It is divided into five sections. The first section is an introduction to IPQoS; the second section is about the tool used for the tests; the third section gives an overview of test configuration; the fourth section gives an interpretation of the test results; the fifth section contains raw test result data in tabular form; and the last section gives some suggestions for further study.

Introduction

During the past few years, the Internet has evolved from a simple network carrying primarily data traffic, into a complex network handling a variety of traffic, ranging from real time audio and video to web traffic. However, in terms of throughput, delay and packet loss, the “best effort” nature of the current Internet is not sufficient to cope with the requirements of this type of traffic.

HP-UX IPQoS can be used to bring an HP-UX node into conformance with the IETF Differentiated Services (DiffServ) model. The key features of HP-UX IPQoS are:

•Conforms to the IETF Differentiated Services (DiffServ) Model.

•Provides differentiated classes of service on outbound traffic by performing traffic conditioning actions. Important traffic classes can take bandwidth away from less important classes, up to user-specified limits.

-Classification occurs when traffic classes are defined in filters.

-Marking occurs when marking attributes are set in policies.

-Metering occurs when bandwidth is reserved for defined traffic classes in policies.

•Allows DSCP and VLAN marking on outbound traffic from the HP-UX server.

-Can assign different DSCP network routing priorities (valid range 0-63).

-Can assigned different VLAN priorities (valid range 0-7).

•Supports traffic classification on broad range of packet attributes.

•Provides provisioned QoS management.

•Supports both IPv4 and IPv6.

HP-UX IPQoS performs the above items by reading the header of an IP packet (plus transport TCP/UDP header) and comparing it to a set of user configured rules. The specific action is taken based on the rules. Because HP-UX IPQoS only reads the IP header, the size of an IP packet does not affect the speed at which HP-UX IPQoS processes the packet.

However, the faster an interface connection is, the more packets per second it can handle. A link capable of 56 Kbps and 1.544Mbps can carry up to 350 and 9650 packets per second, respectively. Faster connections such as 10-baseT (Ethernet) and 100-baseT (Fast Ethernet) can carry up to 62,500 and 625,000 packets respectively.

Because HP-UX IPQoS works the same on all packets, regardless of size, the more packets an interface can handle the more checking HP-UX IPQoS has to do. Therefore, the impact of HP-UX IPQoS on a slower interface is minimal because there are not as many packets for it to check. The performance impact of HP-UX IPQoS on a faster interface is greater, because more packets are passing through, and HP-UX IPQoS must process them all.

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