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The abstract along with the Internet network rapid expansion globally, the application increases day by day, the IP address soon exhausts the contradiction is more prominent, simultaneously to solve the IPv4 design defects, the internet project duty group has developed new generation Internet agreement - IPv6, but because between IPv4 and IPv6 has the very big difference, simultaneously exists numerously based on the IPv4 agreement network and the application, therefore, must use new IPv6 to replace old IPv4 to have a transition period inevitably. We have studied one kind of transition mechanism in view of the above question, and aimed at this transition mechanism design to realize the browser pattern IPv4 client visit to IPv6 server’s.

Key word IPv4 IPv6 transition mechanism double agreement stack proxy service Java 

 

Foreword

      The change which now, the Internet popularization application globally surpassed in historical any new technology to have had the influence which and brings, the practice proved that IPv4 was not only vigorous and healthy, moreover is easy to realize, and had the very good interoperability. These have affirmed the IPv4 agreement fully (IPv4 protocol) the reference design accuracy. But along with the Internet rapidly expand, turns on Internet the network equipment and the movement in above application procedure sharp growth, from this brought the IP address to exhaust rapidly with questions and so on routing list inflation, was also imminent to the IP address range’s expansion. In view of the IP address’s question, IETF (Internet project duty group) proposed the new generation Internet interconnection agreement - - IPv6 agreement (IPv6 protocol), not only it has solved the IPv4 address problem, and improved IP agreement performance ^[1,2]. But in present stage, because Internet is completely the establishment in the IPv4 architecture, all application procedure also defers to IPv4 form writing. How therefore the transition mechanism which as well as produces from this to the IPv6 transition to become by IPv4 for a new research hot spot. In view of IPv4 to the IPv6 transition, we have studied the way which transits with the double agreement stack, followed in IPv4 the proxy service mechanism, the attempt has realized is the browser visits with Firefox through the double agreement stack’s agent server based on the IPv6 homepage.

       Along with the Internet application scope’s expansion, discovered that IPv4 has the insurmountable question, must substitute finally through the new agreement. Usually, the agreement transition is not very easy, from IPv4 to the IPv6 transition is also so. At present because the IPv4 agreement already succeeded the use will have been near for 20 years, was quite already mature based on the IPv4 application procedure and the equipment and has the suitable scale, between the impossible night to complete all promotion change. But on the other hand, IPv6 application procedure and equipment also not mature complete, like this definitely will present many isolated IPv6 networks. How then to complete from IPv4 to the IPv6 transition, develops the IPv6 most important solution question. From this in the quite long time, between the IPv6 node’s correspondence must rely on the original IPv4 network facility, simultaneously the IPv6 node also essential must with the IPv4 node correspondence, therefore the transition is inevitable, and will transit ^[3] to will certainly to be distributional, evolution advance. According to expert’s predict that transition initial period’s Internet by will move the IPv6 agreement equipment to be composed the small network few “the isolated island” and moves the IPv4 agreement equipment to compose “the sea” massively to compose. As shown in Figure 1:

       But with the lapse of time, the IPv4 sea will change gradually is small, but the IPv6 island will be not only getting more and more, will be getting bigger and bigger, and will substitute for IPv4 to form the new next generation Internet network completely finally.

      Considered networking swift development and real world commercial demand, in carries on the IPv4 network to the IPv6 network transition strategy design, the following directive question must follow, in “next generation agreement suggestion standard” (RFC1752), define clearly following transition principle:

1.       The transition way should be gradual and the evolution, protects the IPv4 network equipment’s investment, guarantees in a quite long historical stage, the IPv4 network equipment may in the transition period normally the independent use.

2.      The IPv4 network world and the IPv6 network world seep mutually, long-term coexisting, this requests IPv4 and IPv6 network equipment each other may interlock the intercommunication, realizes interoperability.

3.      The IPv4 network world to the IPv6 network world transient process, IPv4 the expense which promotes to IPv6 should as far as possible low, the transition technology should as far as possible simple, by attracts the user community as soon as possible initiative to the IPv6 transition.

       Because between the IPv4 agreement and the IPv6 agreement does not have the relevance, therefore IPv4 and between the IPv6 architecture also needs to construct the related transition mechanism to support the two to coexist seamlessly.

       Profits from traditional the IPv4 agent server principle, associates the installment has the IPv4/IPv6 double agreement stack on an agent server, then the agent server may take the IPv4 client side to the IPv6 server “the stopover station”, thus realizes both’s indirect correspondence. It realizes the principle like chart specifically 2.

       This plan bases in applies the most universal browser technology, but rewrites browser’s code is directly not realistic, therefore we use one kind of quite direct solution: In the double agreement stack main engine’s transmission level, profits from traditional IPv4 the transmission level agent mechanism carries on “the transformation” to IPv4 and the IPv6 agreement, thus lets only support IPv4 the application procedure not to need to promote can “seamless” visit the pure IPv6 service. Like this we only need to the agent server programming, simultaneously using the socket independence in the network protocol characteristic, complete through the write program to the socket sleeve joint character in certain parameter revision, lets the agent server transfer system’s IPv6 agreement stack to correspond, realizes turns on IPv6. Realizes the above design mentality key is to compiles the revision to complete to the socket sleeve joint character in certain parameter revision and completes the transfer, below is constructs the agent server process related code refinement to be as follows:

 public HttpProxy (Socket s) {socket=s; start(); }

    public void writeLog (int c, boolean browser) throws IOException {

        log.write(c);

    }

    public void writeLog(byte[] bytes, int offset,

             int len, boolean browser) throws IOException {

        for (int i=0; i<len; i  ) writeLog((int)bytes[offset i], browser);

    }

    public String processHostName (String url, String host, int port, Socket sock) {

        java.text.DateFormat cal=java.text.DateFormat.getDateTimeInstance();

        System.out.println (cal.format (new java.util. Date())   "-"  

              url   ""  sock.getInetAddress()  " <BR>");

        return host;

 

public void run() {

         Socket outbound=null;

    try {

        socket.setSoTimeout(TIMEOUT);

        InputStream is=socket.getInputStream();

        OutputStream os=null;

......

                outbound.setSoTimeout(TIMEOUT);

                os=outbound.getOutputStream();

                os.write (line.getBytes());

                os.write ('');

                os.write (host0.getBytes());

                os.write ('');

                ......

......

      Is the same with all thread object, a HttpProxy kind of prime task completes in the run method. the run method has realized a simple state machine, from a Web browser each time read character, continues this process until to have the enough information to discover the goal Web server. Then, run opens one to this Web server’s Socket (, if has many agent servers to link in together, then the run method opens one to chain inside next agent server’s Socket). After opening Socket, run reads in the first part request Socket, then transfers the pipe method. pipe method directly between two Socket by quickest speed execution read-write operation. After having completed the agent server procedure design, must enable the client side to use the proxy, but also needs to carry on the corresponding establishment in the client side browser, namely disposes the agent server in the browser, has like this completed the complete process.

      The Internet trend of development will prove that IPv4 will certainly to substitute by IPv6, but its transient process also certainly can be long, difficult. Therefore, is not only advantageous to the transition question’s research in completes the transition, moreover can also safeguard the Internet network long-term stability movement. This design not can only complete the transformation simultaneously to use the low cost pattern, forms a solution, system test’s result indicated adopts the technology is reasonable, can meet the actual movement needs.

 

 

[1] week Ling, Yin rosy cloud, Wu Jianping. Realizes IPv4 to the IPv6 transition tunnel technology. Computer project and application, 2002:156

[2]Jim Bound, L aurent Toutain. Dual Stack transition mechanism(DSTM) http://www.ietf.org/interner-drafts/draft-ietf-ngtrans-dstm-00.txt, October,1999

[3]R.Hinden. RFC2732: Format for Literal IPv6 Address in URL’s, 2002-12