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1. What is the IP protocol?
IP is the acronym for ‘Internet Protocol’. An IP is the method, or protocol, by which data is sent from one computer to another over the Internet.
2. What is an IP address?
An IP address is a unique identifier that is assigned to every device connected to an IP network. As a result, the various devices connected to the network communicate with each other using their IP address as an identifier. In version 4 of the IP protocol, addresses consist of 32 bits. This is equivalent to 232 different IP addresses. In version 6 of the IP protocol, addresses consist of 128 bits leading to 2128 different IP addresses.
3. What is IPv6?
IPv6 is short for "Internet Protocol Version 6". IPv6 is the "next generation" protocol designed by the IETF to replace the current version of the Internet Protocol, IP Version 4 (IPv4). Most of today's Internet connections use IPv4, the latter being more than twenty years old. IPv4 has been remarkably resilient in spite of its age. However, it is beginning to experience problems, the main problem being the growing shortage of IPv4 addresses. IPv4 addresses are constantly on demand by the new machines needing to connect to the Internet.
IPv6 fixes a number of problems in IPv4, such as the limited number of available IPv4 addresses. It also adds many improvements to IPv4 in areas such as routing and network auto-configuration. IPv6 is expected to gradually replace IPv4, with the two coexisting for a number of years during a transition period.
4. What are the major advantages of IPv6?
These can be summarised as follows:
Scalability: IPv6 has a 128-bit address while IPv4 has a 32-bit address. Therefore, IPv6 provides more IP addresses; IPv6 offers a 2128 space (3.4 x 1038 addresses). Such an address space is sufficient to allocate about 1030 addresses per person on this planet.
Security: IPv6 includes security in its specifications. This includes information encryption and the authentication of the source from which the information is arriving.
Plug and Play: IPv6 includes the ‘plug and play’ mechanism to facilitate the connection of user equipment to a network. With the ‘plug and play’ facility, network devices can connect to the network without the need of manual configuration and without the need of any servers, such as a DHCP server.
Mobility: IPv6 provides more efficient and robust mobility mechanisms.
More clear and optimised specifications: IPv6 has adopted the good practices of IPv4 and removed obsolete IPv4 characteristics. Hence, the better optimised characteristics of IPv6.
Addressing and routing: IPv6 improves the addressing and routing hierarchy. A larger address space allows the allocation of larger address blocks to the Internet Service Providers (ISPs). This allocation, in turn, allows the ISP to aggregate the prefixes of all its customers into a single prefix and announce this one prefix to the IPv6 Internet.
Extensibility: IPv6 has been designed to be extensible and offers optimised support for new options and extensions.
5. Is there another, easier solution than IPv6?
There is an obvious solution, namely, the renumbering and the reallocation of the IPv4 addressing space. However, this is not a simple feat (even unthinkable in some networks) since it requires worldwide coordination efforts. Moreover, although the renumbering and the reallocation of the IPv4 address space would temporarily solve the exhaustion of IPv4 address space issue, the same problem would still come to surface in the coming years as the number of people connecting to the Internet continues to increase. Therefore, the renumbering and the reallocation of the IPv4 addressing space would only be postponing the exhaustion problem to a later stage.
6. What is the solution used nowadays?
As a temporarily solution to alleviate the lack of IPv4 addresses, NAT (Network Address Translation) is being deployed. NAT is a networking protocol that allows networks of private IP addresses to be set up using a single real IPv4 address. Using NAT, a local area network (LAN) can be set up with no special configuration of the Internet connection. To the Internet, the network looks like one computer, but on the LAN, every computer has its own internal IP address.
7. Why cannot NAT be adopted on a permanent basis?
Many applications, especially emerging peer-to-peer applications, cannot operate correctly using NAT. This implies that many applications cannot be used if NAT is being deployed in a network. The following is a list of such applications:
- Multimedia applications, including videoconference applications, voice over IP and video on demand, cannot be utilised on NAT enabled devices. The protocols used for such applications, namely, RTC and RTCP (Real-time Transport Protocol and Real Time Control Protocol respectively) use UDP with dynamic allocation of ports. NAT does not provide support for the latter.
- Kerberos authentication requires the source address. NAT devices modify the source address, this address being present in the IP header and therefore, this type of authentication is not possible.
- IPSec allows data authentication, integrity and confidentiality. However, since NAT modifies the address in the IP header, IPsec loses its integrity when NAT is used.
- Although NAT supports multicast, its configuration results to be so complicated that it is rarely deployed.
8. What is the IPv6 address format?
An IPv6 address has the following format:
2001:0ba0:01e0:d001:0000:0000:d0f0:0010
In converse to the 32 bits making up an IPv4 address, an IPv6 address consists of 128 bits. The IPv6 address is represented by 8 groups; every group consisting of 16 bits. The groups are separated by a ":" and they are represented by 4 hexadecimal ciphers. Every cipher has a value between 0 and 15 (0,1,2, ... A, B, C, D, E, F with A=10, B=11, C=12, D=13, E=14, F=15).
More information on the IPv6 addressing format can be found in the following documents:
http://www.cisco.com/application/pdf/en/us/guest/products/iosswrel/c1127/cdccont_0900aecd8018e369.pdf
http://download.microsoft.com/download/e/9/b/e9bd20d3-cc8d-4162-aa60-3aa3abc2b2e9/IPv6.doc
http://www.ipv6style.jp/en/tech/20041117/index.shtml
9. Which are the special IPv6 addresses?
Auto-return or loopback virtual address. This address is specified in IPv4 with the 127.0.0.1 address. In IPv6 this address is represented as ::1.
Not specified address (::). This address will never be allocated to any node since it is used to indicate the absence of an address.
IPv6 over IPv4 dynamic/automatic tunnels. These are designated as IPv4 compatible IPv6 addresses, and permit the sending of IPv6 traffic over IPv4 networks in a transparent way. They are represented as ::, for example, ::156.55.23.5.
IPv4 over IPv6 addresses automatic representation: these permit IPv4-only nodes to work on IPv6 networks. These addresses are mapped from IPv4 to IPv6 addresses. They are represented as ::FFFF: , for example, ::FFFF.156.55.43.3
10. What is understood by auto-configuration of IPv6?
The address auto-configuration feature is built into the IPv6 protocol to facilitate intranet-wide address management, enabling a large number of IP hosts to easily discover the network and obtain new, and globally unique, IPv6 addresses associated with their location. The auto-configuration feature enables ‘plug-and-play’ Internet deployment. As a result, network devices could connect to the network without manual configuration and without any servers, such as DHCP servers.
11. Is it possible to simultaneously have an IPv4 and an IPv6 address?
Yes. Most of the operating systems currently supporting IPv6 also support IPv4, hence allowing for the simultaneous use of the two protocols. In this way, it is possible to communicate with both IPv4 and IPv6 networks instead of being restricted to one type of network only. In addition, the support of both protocols will permit the use of applications that are specifically designed to work with only one of the two protocols.
12. Which techniques are being used to allow for the simultaneous operation of IPv4 and IPv6?
A number of techniques have been adopted in order to allow for the simultaneous operation of IPv4 and IPv6. The techniques most frequently used are:
Deploying IPv6 over a dual-stack backbone
Deploying IPv6 over IPv4 tunnels
Deploying IPv6 over dedicated data links
Deploying IPv6 over an MPLS backbone
More information on these techniques can be found on
http://www.cisco.com/application/pdf/en/us/guest/products/iosswrel/c1127/cdccont_0900aecd8018e369.pdf
http://download.microsoft.com/download/7/4/1/741daf62-02d6-40f3-b082-701b5acc56d6/IPv6Trans.doc
13. How is IPv6 installed on Windows XP?
To install the IPv6 Protocol on Windows XP:
i) Log on with a user account that has the privileges to change the network configuration.
ii) If the version of XP that is installed is without Service Pack 1:
a) Open a command line (Start -> Programs -> Accessories -> Command Prompt)
b) Write ‘ipv6 install’ in the command line
iii) If the version of XP has Service Pack 1 installed (or later), or if Windows 2003 is being used:
a) Select Properties, in My Network Places, and select the network card. Subsequently, for the network card, select Properties -> Install -> Protocol -> IPv6.
b) The same procedure can be performed via the command line using the command ‘netsh interface ipv6 install’.
14. How can one know if the IPv6 protocol is installed on Windows XP or Windows 2003?
One has to write ‘ipv6 if’ (if using Windows 2000 or XP) or ‘ipconfig’ (if using XP with SP1 or later or Windows 2003) on the command line. If IPv6 is installed, its configuration will appear.
15. Where can one find more information regarding the operation of IPv6 on a Windows system?
The following URLs contain answers to frequently asked questions about IPv6 in different Windows platforms:
http://www.microsoft.com/technet/prodtechnol/winxppro/Plan/FAQIPV6.asp
http://www.microsoft.com/ipv6
16. Is it possible to encrypt data on a Windows XP machine that is using the IPv6 protocol?
Windows Server 2003 and Windows XP have an IPSec feature. IPSec is also supported in an IPv6 environment. However, IPv6 does not support the encryption of payload data. The Windows IPv6 IPSec feature can, at present, be used to authenticate the server and to prevent data repudiation. Also, at present, the Windows IPv6 IPSec does not support Internet Key Exchange (IKE), an automatic exchange mechanism.
17. How can one install IPv6 on a Linux system?
In order to install IPv6 on a Linux machine, the kernel must support IPv6 too. Therefore, the kernel must be compiled using the following options:
Section ‘Networking Options’ to ‘The IPv6 protocol’
18. How can one know if IPv6 is installed on Red Hat Linux?
To check if the protocol is installed, the following Linux command can be used:
# test -f /etc/sysconfig/network-scripts/network-functions-ipv6 && echo "Main IPv6 script library exists"
19. Where can one find a detailed guide about IPv6 and Linux?
The following URL has a detailed guide for the deployment of IPv6 in Linux:
http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/pdf/Linux+IPv6-HOWTO.pdf
20. Is IPv6 more secure than IPv4?
The security provided by IPv6 is in many ways the same as that provided by IPv4. The basic mechanism for transporting packets across the network is mainly unchanged and the upper layer protocols that transport the actual application data are mostly unaffected. Since IPv6 mandates the inclusion of IP Security (IPSec), it is often stated that IPv6 is more secure than IPv4. Ideally, with well-coded applications, a robust identity infrastructure and efficient key management, this statement is true. However, in reality, the same problems hindering the deployment of IPv4 IPSec also affect the deployment of IPv6 IPSec. In addition, most security breaches occur at the application level. Therefore, for such breaches, even the successful deployment of IPSec with IPv6 does not guarantee any additional security, except for determining the source of the attack.
The URLs below refer to documents and articles related with IPv6 and security
http://www.seanconvery.com/ipv6.html
http://www.seanconvery.com/v6-v4-threats.pdf
http://www.6net.org/events/workshop-2003/marin.pdf
http://www.ipv6style.jp/en/tech/20040707/index.shtml
http://www.ipv6style.jp/en/tech/20040722/index.shtml
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