Transition Mechanisms on Windows Server Operating Systems. Shaneel Narayan ... Protocol offers substantially more network and host addresses, however ...
2010 International Conference On Computer Design And Appliations (ICCDA 2010)
Network Performance Evaluation of IPv4-v6 Configured Tunnel and 6to4 Transition Mechanisms on Windows Server Operating Systems
Shaneel Narayan, Sotharith Tauch Department of Computing Unitec Institute of Technology Auckland, New Zealand snarayan@unitec. ac. nz
Abstract- The potential exhaustion of IPv4 addresses initiated the development of IPv6. The new version of the Internet Protocol offers substantially more network and host addresses, however transition from current to the new version has been remarkably slow. There are multiple reasons for the sluggish transition: complexity and enormousity being the forerunners. Thus for the interim, various transition mechanisms have been developed.
Each mechanism has its associated benefits and
weaknesses. In this paper two such mechanisms, namely configured tunnel and 6t04 transition mechanism, have been empirically evaluated for performance. Both mechanisms are implemented on
two different Windows Server
operating
systems and performance related metrics like throughput, delay, jitter and CPU usage of the transition end nodes are measured. The results obtained on the test-bed show that TCPIUDP throughput and jitter values of the two mechanisms are similar, but delay and CPU reading are significantly different depending on the choice of transition mechanism and operating system. Keywords- IPv4, IPv6, tunnel,
6t04,
transition
performance
mechanism,
evaluation,
network,
configured Windows
operating system.
I.
INTRODUCTION
TCP/IP is the protocol suite that allows Internet to operate across the globe. Internet Protocol (IP) is one of the protocols within this protocol suite and IP version 4 was the first version that was widely deployed. Internet Protocol is the standard protocol being used on the Internet which allows computers to be able to communicate in order to exchange information such as data and voice (VoIP). Currently IPv4 is widely used across the Internet; however this version has inherent issues like insufficient public IP addresses, security and performance issues that are hindering the growth of the Internet. Nowadays, most mobile devices and similar require IP addresses, and with rapid growth in technologies incorporating such devices, the demand for IP addresses is way beyond the theoretical limits of the current IP architecture. This problem was foreseen in the late 1990 and in response Internet Engineering Task Force (IETF) began work on the development of a new version of Internet Protocol, IPv6. This new version has lots of improvements including; increased address space from 232 to 2128, enhanced security, enhanced end user benefits, mobility support and integrated Quality of Service (QoS). However, IPv6 data header is twice in size to that of its predecessor,
978-1-4244-7164-5/$26.00 © 2010 IEEE
implying that IPv6 has a higher overhead associated with it thus performance degradation. There are numerous predictions related to exhaustion of IPv4 addresses, all predictions indicate that this will happen soon rather than later. Migrating from IPv4 to IPv6 is complicated and cannot be done in a short period of time. The size and complexity of the Internet cause this migration task to become enormously difficult and time consuming undertaking. IETF took this migration issue into consideration and came up with transition mechanisms as interim solutions that allow IPv4 to be able to operate alongside IPv6 networks. These transition mechanisms are discussed in the next section, and performance of two such mechanism, configured tunnel and 6t04, is the subject of this research. In this paper, configured tunnel and 6t04 are implemented on two Windows Server operating systems and performance related metrics have been measured on a test bed setup. The rest of the paper is organized as follows: Section II contains a background on transition mechanisms, Section III discusses some of similar work undertaken by other researchers, and Section IV outlines the experimental setup used in this research. We present the results and discuss the findings in Section V. Finally, the research is concluded. II.
BACKGROUND
We present an overview of some common IPv4-v6 transition mechanisms. I) Dual Stack: This is a straightforward transition mechanism where network nodes are stacked with both IPv6 and IPv4 protocols. These IPv6IIPv4 nodes use IPv6 stack to communicate with IPv6 nodes, and IPv4 for communicating with IPv4 networks. Although this solution is practical, all network devices (such as routers, switches, bridges, gateways, etc) end up being dual stacked as well. The additional burden makes network devices inefficient and does not reduce the demand for global routable IPv4 addresses. 2) Protocol Translation: This mechanism works for pure IPv6 network when communicating with nodes on an IPv4 network. Protocol translation techniques solves the problems that dual stack mechanisms exhibit, and depends on some intermediary device or service that convert packet headers at network border. Three protocol translation techniques are prevalent:
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i. Dual Stack Application Level Gateway (DS-ALG): A dual stack IP device is used which can access both IPv4 and IPv6 services natively. This is a simple and robust solution, however requires all clients to be configured to use ALG and will work for specific ALG-supported applications only. ii. Network Address Translator - Protocol Translator (NAT-PT): This is similar to traditional IPv4 NAT; how ever it also has protocol translation. This uses are pool of IPv4 addresses for assignment to IPv6 nodes on a dynamic basis as sessions are initiated across IPv4-IPv6 boundaries. The IPv6 address binds to IPv4 address to give transparent routing for datagrams traversing between address realms. Assignment of IPv4 addresses is done by the border router. iii. Dual Stack Transition Mechanism (DSTM). A DSTM server provides a temporary IPv4 address to dual stack nodes on needs to have basis when IPv6 node wishes to correspond with a node on IPv4 network. The IPv6 node configures its IPv4 stack with the allocated address and tunnels the packets to the DSTM gateway at the edge of the network. The gateway has the responsibility to encapsulate or decapsulate packets as traffic transits through network border. 3) Tunneling: This provides a method to carry IPv6 traffic to other networks using current IPv4 routing infrastructure. IPv6 datagram are encapsulated within IPv4 packets and routered through IPv4 regions of the internetwork. The begin and the end points of the tunnel has to be IPv6/IPv4 dual stacked nodes. Router-to-router, host to-router, router-to-host and host-to-host are the four possible configurations and there are several types of tunnels: i. Configured Tunnel: IPv6 data is encapsulated within IPv4 packet at the originating end point and then trans-ported through a tunnel. At the exit point of the tunnel, the packet is decapsulated. The tunnel endpoint ad-dresses are determined from the configuration information that is stored at the encapsulating endpoint (hence named configured tunnel). Configured tunnels can be defined to go between router-to router, host-to-router, host-to-host or router-to-host. Normally a tunnel broker (a server that manages tunnel requests from users) is employed with this technique. ii. Automatic Tunnel: IPv6 packet is tunneled all the way to the final destination. There are no pre-configured tunnels and the nodes that perform automatic tunneling are assigned an IPv4-compatible IPv6 address. Since IPv6 packet's destination is the tunnel endpoint, IPv6 packet's destination address determines the tunnels endpoint. This technique is named automatic tunneling because the endpoint address is automatically determined from the embedded IPv4 address of the data's IPv6 address. iii. 6 to 4: This allows communication from one IPv6 site to another over an IPv4 network without the need for an explicitly configured tunnel or requiring IPv4-compatible IPv6 addresses. There is no end node configuration and edge router configuration is minimal. When transporting data, node sends IPv6 packets to the destination and these packets are tunneled in IPv4 between the edge 6 to 4 routers of the two networks.
iv. 6 over 4: This is an automatic mechanism for establishment of a tunnel that is used to provide unicast and muticast connectivity between IPv6 nodes via an IPv4 network. A virtual link is created between the two networks and IPv6 multicast addresses are mapped to IPv4 addresses to enable network discovery. III.
RELATED RESEARCH
The Internet Protocol versions and IPv4/IPv6 transition mechanisms are widely researched. Numerous research exit on various threads in the topic, and here we present a few relevant to this research undertaking. Realizing the promises that offers IPv6 when deployed on wide scale is discussed in [ I]. Existing transition mechanisms are discussed in detail together with the associated technical and security issues. This paper states that IPv6 technology is evolutionary and not revolutionary, based on user demands. Various constraints and security issues are discussed in [2] and [3]. Compatibility and operability between IP versions and hints of complications with transition mechanisms are presented. Development of transition mechanisms (and reconfiguring already existing ones to increase performance) has been researched extensively. In [4] 4t06 Dual Stack Transition Mechanism (4t06 DSTM) is proposed and its performance has been evaluated under several conditions using simulation. Merits of using 6t04 transition mechanism are discussed in [5] and its capabilities compared with tunnel brokering techniques. Structure of a new IPv6 transition mechanism is discussed in [6] based on end-to-end tunneling architecture; however no comparison of its quality has been made with other mechanisms. Researches similar to above, where aspects of IPv4/IPv6 transition are also discussed, exist in [7], [8], [9], [10] and [11]. Researches that specifically focus on performance evaluation of transition mechanism also exist in literature. Using simulation, DSTM performance using applications like Real Audio, CBR over UDP and FTP over TCP it has been shown that end-to-end delays are significant [12]. DSTM and 6t04 performance metrics is compared [13]. Similar research is undertaken in [14] and [15]. Test-bed performance analysis on operating systems like Red Hat and FreeBSD with Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) has been conducted in [16] and empirically shows that metrics values are different in various scenarios. In [17] DSTM with Windows 2000 performance is evaluated and shown host-to-host encapsulation transition mechanism performed better than IPv6 protocol stack or router-to-router tunneling. In this research we analyze performance of two transition mechanisms, namely configured tunnel and 6t04, on two common Windows operating systems on a test-bed. No previous research has undertaken to empirically evaluate such performance. Test-bed setup is discussed next.
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IV .
EXPERIMENTAL SETUP 95
Four computers (Intel Core 2 Duo E6300, 1. 866 GHz: RAM 2GB) were connected using Cat5e cables as in Figure I. All computers had two network interfaces (Broad-com NetXtreme Gigabit and Ethernet Intel 100s Fast Ethernet) with computers at the ends using faster NICs. Computers at the ends acted as the client nodes while computers in the middle were configured as routers. Keeping all hardware
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