By Aaron Thomas

Quick Network Protocol Intro. Layers 1- 3 of the 7 layer OSI Open System Interconnection Reference Model  Layer 1 Physical Transmission (electricity, light, etc.) Ex. Ethernet  Layer 2 Encoding/Decoding or physical medium into Bits. Handling of Flow Control, Layer 1 Error Handling/Correction. Ex. Ethernet  Layer 3 Virtual Addressing, Routing, Ex. IPv4, IPv6

The Most Common Layer 3 Transport Protocols  IPv4 IETF RFC 791 (1981) Backbone transport protocol of the Internet and most computer networks Uses 32bits to Uniquely Identify Hosts allowing for ~4.3 Billion connected devices Variable length header (20+bytes)  IPv6 IETF RFC 2460 (1998) Created to address Ipv4’s limitations Uses 128bits for Unique Host Identification Strict 40 byte header Extension Headers for additional features.

IPv4/IPv6 Header Differences IPv4 Header 20+ Bytes IPv6 Header Fixed 40 Bytes

Why Transition to IPv6?  INNA(Internet Assigned Numbers Authority) and ARIN (American Registry for Internet Numbers) recommend transition to IPv6 as soon a possible. [1,2]  All IPv4 address will be exhausted sometime in 2011/2012 [1]  Improved Routing efficiency  Improved Header Efficiency (Hardware)  Mobility Enhancements  Security Enhancements

IPv6 Possible Drawbacks/Issues  New Hardware/Software Costs Transitional Issues (Running IPv4 and IPv6)  Increased Header size. (Double) IPv4 was 20bytes + a variable addition IPv6 is always 40bytes + extension headers Increased Overhead is very noticeable with smaller packet sizes  New network code in routers and operating systems. ? Increased Delay/Jitter/CPU usage ? Decreased throughput

Why IPv6 and Windows 7?  Transition to IPv6 must happen in the next 2-5 years.  Windows 7 will likely be the most utilized client operating system for enterprises during the next 2-5 years.  Windows Server 2008 R2 uses a similar code base as Windows 7 and will likely be the server of choice during the same time period.

Experimental Setup  2 Dell Optiplex 755’s High Performance Modern Workstations Dual Core CPU’s, 2G RAM, Gig NIC  HP ProCurve 3500yl High Performance Modern Intelligent Edge Layer 3 Switch 24 Gig Interfaces IPv4/IPv6 Aware IPv4/Ipv6 capable Routing processor (IPv4 implemented IPv6 in the near future)

Software used for Testing  IPerf/JPerf Bandwidth testing. Used to test the maximum throughput of a link (IPv4/IPv6) Client/Server Model  D-ITG (Distributed Internet Traffic Generator) Packet generation tool. Measures delay/jitter/bitrate Can create many different flow types (TCP/UDP, packets per second, Packets sizes, etc.) Client Server Model

Maximum Throughput using JPerf (IPerf)

Percent of Total Packet Data Used by TCP/UDP Headers

CPU Utilization using Windows Performance Monitor. Taken during JPerf (IPerf) Run’s

Average Delay in Milliseconds For Various Payload Sizes

Average Jitter in Milliseconds For Various Payload Sizes

Conclusions  Maximum Obtainable Throughput is less for IPv6 due to the increased header size.  There are Insignificant differences in delay or Jitter for IPv6 vs. IPv4. The experimental results did not favor either IPv4 or IPV6.  Very small almost negligible increase in CPU usage when using IPv6 likely due to the increased overhead of the larger addresses.

Final Analysis  Consideration should be taken when transitioning to IPv6 for Applications that have small payloads. Situations where the link is expected to be saturated.  IPv6 and IPv4 have similar performance characteristics and system loads. Windows 7 handled IPv6 and IPv4 Traffic without significant differences in performance at Gig Speeds. HP ProCurve Switches running the 3500 series code and processor base handled IPv4 and IPv6 without noticeable performance differences at Gig Speeds.

References  [1] Huston, Geoff, “IPv4 Unallocated Address Space Exhaustion”, RIPE 55 Conference, Amsterdam, Netherlands, October, 2007.Netherlands  [2] “ARIN Board Speaks Out on Major Issues”, ARIN Report, September,  [3] Deering, S., Hinden, R., “Internet Protocol, Version 6 (IPv6) Specification. Request for Comments 2460,” Network Working Group, December  [4] “Internet Protocol: Darpa Internet Program Protocol Specification. Request for Comments 791,” Internet Engineering Task Force, September 1981.

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