CISCO - IPv6 (INTERNET PROTOCOL VERSION 6):

FIRST UNDERSTAND WHAT IS AN IP ADDRESS IN NETWORKING:

An Identifier For A Computer Or Device On A TCP/IP Network. Networks Using The TCP/IP Protocol Route Messages Based On The IP Address Of The Destination.

An IP address can be private - for use on a local area network (LAN) - or public - for use on the Internet or other wide area network (WAN). IP addresses can be determined statically (assigned to a computer by a system administrator) or dynamically (assigned by another device on the network on demand).

TWO TYPE OF IP ADDRESSING STANDARDS ARE IN USE TODAY: THAT ARE IPv4 & IPv6.

1. IPv4: The IPv4 standard is most familiar to people and supported everywhere on the Internet, but the newer IPv6 standard is planned to replace it and starting to be deployed. IPv4 addresses consist of four bytes (32 bits). Each byte of an IP address is known as an octet. Octets can take any value between 0 and 255. Various conventions exist for the numbering and use of IP addresses.

WHY WE GO FOR IPv6: An Internet Protocol (IP) is the “language” and set of rules computers use to talk to each other over the Internet. The existing protocol supporting the Internet today - Internet Protocol Version 4 (IPv4) - provides the world with only 4 billion IP addresses, inherently limiting the number of devices that can be given a unique, globally routable address on the Internet.

2. IPv6: IPv6, formerly named IPng (next generation), is the latest version of the Internet Protocol (IP). IP is a packet-based protocol used to exchange data, voice, and video traffic over digital networks. IPv6 was proposed when it became clear that the 32-bit addressing scheme of IP version 4 (IPv4) was inadequate to meet the demands of Internet growth. After extensive discussion it was decided to base IPng on IP but add a much larger address space and improvements such as a simplified main header and extension

headers. IPv6 is described initially in RFC 2460,

Internet Protocol, Version 6 (IPv6) Specification, issued by the Internet Engineering Task Force (IETF). Further RFCs describe the architecture and services supported by IPv6.

It is the new addressing scheme that will eventually replaces all IPv4 addresses. The IPv4 address scheme is no longer adequate to meet the needs of the growing Internet, and growing Intranets. IPv6 was also designed to increase routing performance and network scalability issues. IPv6 addresses are128 bits in length.

The emergence of IPv6, providing the world with an exponentially larger number of available IP addresses, is essential to the continued growth of the Internet and development of new applications leveraging mobile Internet connectivity. Although the information technology (IT) community has come up with workarounds for this shortage in the IPv4 environment, IPv6 is the true long-term solution to this problem.

INTRODUCTION OF IPv6:

Internet Protocol version 6 (IPv6) is a version of the Internet Protocol (IP) that is designed to succeed Internet Protocol version 4 (IPv4). The architecture of IPv6 has been designed to allow existing IPv4 users to transition easily to IPv6 while providing services such as end-to-end security, quality of service (QoS), and globally unique addresses.

The larger IPv6 address space allows networks to scale and provide global reachability. The simplified IPv6 packet header format handles packets more efficiently.

IPv6 prefix aggregation, simplified network renumbering, and IPv6 site multihoming capabilities provide an IPv6 addressing hierarchy that allows for more efficient routing. IPv6 supports widely deployed routing protocols such as Routing Information

Protocol (RIP), Integrated Intermediate System-to-Intermediate System (IS-IS),

Open Shortest Path First for IPv6, and multiprotocol Border Gateway Protocol (BGP). Other available features include stateless auto configuration, enhanced support for Mobile IPv6, and an increased number of multicast addresses.

IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the long-anticipated IPv4 address exhaustion, and is described in Internet standard document RFC 2460, published in December 1998.[1] Like IPv4, IPv6 is an Internet Layer protocol for packet-switched internetworking and provides end-to-end datagram transmission across multiple IP networks.

While IPv4 allows 32 bits for an Internet Protocol address, and can therefore support 232 (4,294,967,296) addresses, IPv6 uses 128-bit addresses, so the new address space supports 2128 (approximately 340 undecillion or 3.4×1038 ) addresses. This expansion allows for many more devices and users on the internet as well as extra flexibility in allocating addresses and efficiency for routing traffic. It also eliminates the primary need for network address translation (NAT), which gained widespread deployment as an effort to alleviate IPv4 address exhaustion.

IPv6 NAT:

Network Address Translation (NAT) allows multiple devices to use local private addresses within an enterprise while sharing one or more global IPv4 addresses for external communications.While NAT has to some extent delayed the exhaustion on IPv4 address space for the short term, it complicates general application bi-directional communication. IPv6 eases the complexity of providing end-to-end security. IPv6 removes the common motivation for the use of NAT since global addresses will be widely available.

Cisco decided to provide the NAT feature related to both protocols and address translation between IPv6 and IPv4 in IOS from the beginning. This is an important value-added feature that will greatly simplify the introduction of IPv6 in Enterprise Networks.

NAT DEVICES WOULD ENABLE the interconnection of hosts that have IPv6- only addresses (hosts that do not have IPv4-compatible addresses) with hosts that have IPv4-only addresses. If assigning globally unique IPv4 addresses would become impossible (due to the exhaustion of the IPv4 address space) before a sufficient number of the Internet hosts would transition to IPv6, then NAT devices would allow continuing (and completing) the transition, even in the absence of the globally unique IPv4 addresses. Cisco IPv6 NAT is designed to allow an IPv6 network to access and be accessed by the IPv4 Internet.

IPV6 ADDRESS SYNTAX:

IPv4 addresses are represented in dotted-decimal format. The 32-bit IPv4 ad-dress is divided along 8-bit boundaries. Each set of 8 bits is converted to its decimal equivalent and separated by periods. For IPv6, the 128-bit address is divided along 16-bit boundaries, and each 16-bit block is converted to a 4-digit hexadecimal number and separated by colons. The resulting representation is called colon hexadecimal.

THE FOLLOWING IS AN IPV6 ADDRESS IN BINARY FORM:

00100001110110100000000011010011000000000000000000101111001110110000001010101010000000001111111111111110001010001001110001011010

THE 128-BIT ADDRESS IS DIVIDED ALONG 16-BIT BOUNDARIES:

0010000111011010 0000000011010011 0000000000000000 00101111001110110000001010101010 0000000011111111 1111111000101000 1001110001011010

EACH 16-BIT BLOCK IS CONVERTED TO HEXADECIMAL AND DELIMITED WITH COLONS. THE RESULT IS:

21DA:00D3:0000:2F3B:02AA:00FF:FE28:9C5A

FOLLOWING ARE TWO EXAMPLES OF IPV6 ADDRESSES:

2001:0DB8:7654:3210:FEDC:BA98:7654:3210

2001:0DB8:0:0:8:800:200C:417A

It is common for IPv6 addresses to contain successive hexadecimal fields of zeros. To make IPv6 addresses less cumbersome, two colons (::) may be used to compress successive hexadecimal fields of zeros at the beginning, middle, or end of an IPv6 address (the colons represent successive hexadecimal fields of zeros).

IPv6 address representation is further simplified by suppressing the leading zeros within each 16-bit block. However, each block must have at least a single digit. With leading zero suppression, the result is:

21DA:D3:0:2F3B:2AA:FF:FE28:9C5A

128 bits, enormous number

HOW TO WRITE THEM:

8 BLOCKS OF 16 BITS, EACH WRITTEN IN HEX SEPARATED BY:

Ø 3ffe:2a00:100:7020:0:0:dead:beef

Ø 2001:700:700:1:0:0:0:2

Ø 0-compression, consecutive 0 blocks written as ::, can be used only once (else ambiguous)

Ø 2001:700:700:1::2

Ø FE80:0000:0000:0000:0202:B3FF:FE1E:8329

EXAMPLE OF A COLLAPSED IPV6 ADDRESS:

FE80::0202:B3FF:FE1E:8329

THE :: (CONSECUTIVE COLONS) NOTATION CAN BE USED TO REPRESENT FOUR SUCCESSIVE 16-BIT BLOCKS THAT CONTAIN ZEROS.

EXAMPLE OF AN IPV6 ADDRESS THAT INCLUDES A PORT NUMBER:

AN IP ADDRESS THAT CONTAINS A PORT NUMBER:

[2001:db8:0:1]:80

The brackets are necessary only if also specifying a port number. Brackets are used to separate the address from the port number. If no port number is used, the brackets can be omitted.

As an alternative, the block that contains a zero can be collapsed. Here is an example:

[2001:db8::1]:80

Example of an IPv6 Address That Includes a URL:

Here is an example of an IP address that contains a URL:

http://[2001:db8:0:1]:80

The http:// prefix specifies a URL. The brackets are necessary only if also specifying a port number. Brackets are used to separate the address from the port number. If no port number is used, the brackets can be omitted.

COMPRESSING ZEROS:

Some types of IPv6 addresses contain long sequences of zeros. To further simplify the representation of IPv6 addresses, a single contiguous sequence of 16-bit blocks set to 0 in the colon hexadecimal format can be compressed to ::, known as a double colon.

For example: the link-local address of FE80:0:0:0:2AA:FF:FE9A:4CA2 can be compressed to FE80::2AA:FF:FE9A:4CA2. The multicast address FF02:0:0:0:0:0:0:2 can be compressed to FF02::2.

Ø NOTE: You cannot use zero compression to include part of a 16-bit block. For example, you cannot express FF02:30:0:0:0:0:0:5 as FF02:3::5, but FF02:30::5 is correct.

HOW MANY BITS IN ::?

To determine how many 0 bits are represented by the ::, you can count the number of blocks in the compressed address, subtract this number from 8, and then multiply the result by 16. For example, in the address FF02::2, there are two blocks (the “FF02” block and the “2” block.) The number of bits expressed by the :: is 96 (96 = (8 − 2) × 16).

Zero compression can be used only once in a given address. Otherwise, you could not determine the number of 0 bits represented by each instance of ::.

IF DON'T UNDERSTAND WE’LL TECH YOU ANOTHER WAY:

So you certainly already know that 32-bit IPv4 addresses are represented by breaking them into four 8-bit segments and writing each of those segments in decimal between 0 and 255, separating them with periods; hence the term dotted decimal.

Breaking them up into eight 16-bit segments represents 128-bit IPv6 addresses. Each segment is written in hexadecimal between 0x0000 and 0xFFFF, separated by colons.

An example of a written IPv6 address is:

3ffe:1944:0100:000a:0000:00bc:2500:0d0b

Remembering more than a few such addresses is practically impossible, and writing them is not much fun either. Fortunately, there are two rules for reducing the size of written IPv6 addresses. The first rule is

The leading zeroes in any 16-bit segment do not have to be written; if any 16-bit segment has fewer than four hexadecimal digits, it is assumed that the missing digits are leading zeroes.

In the example address, the third, fourth, fifth, sixth, and eighth segments have leading zeroes. Using the first address compression rule, the address can be written as

3ffe:1944:100:a:0:bc:2500:d0b

Notice that only leading zeroes can be omitted; trailing zeroes cannot, because doing so would make the segment ambiguous. You would not be able to tell whether the missing zeroes belonged before or after the written digits.

Notice also that the fifth segment in the example address is all zeroes, and is written with a single zero. Many IPv6 addresses have long strings of zeroes in them. Take, for example, the following address:

ff02:0000:0000:0000:0000:0000:0000:0005

This address can be reduced as follows:

ff02:0:0:0:0:0:0:5

However, using the second rule can reduce this address even further:

Any single, contiguous string of one or more 16-bit segments consisting of all zeroes can be represented with a double colon.

Using this rule, the example address can be represented as the following:

ff02::5

The increased convenience in writing such an address is obvious. But notice that the rule says only a single contiguous string of all-zero segments can be represented with a double colon. Using the double colon more than once in an IPv6 address can create ambiguity. Take, for example, the following address:

2001:0d02:0000:0000:0014:0000:0000:0095

Either of the following reductions of the address is correct because they use a double colon only once:

2001:d02::14:0:0:95 2001:d02:0:0:14::95

But the following reduction is illegal because it uses the double colon twice:

2001:d02::14::95

It is illegal because the length of the two all-zero strings is ambiguous; it could represent any of the following IPv6 addresses:

2001:0d02:0000:0000:0014:0000:0000:0095 2001:0d02:0000:0000:0000:0014:0000:0095 2001:0d02:0000:0014:0000:0000:0000:0095

Unlike IPv4, in which the prefixthe network portion of the addresscan be identified by a dotted decimal or hexadecimal address mask or a bitcount, IPv6 prefixes are always identified by bitcount. That is, the address is followed by a forward slash and a decimal number indicating how many of the first bits of the address are the prefix bits. For example, the prefix of the following address is the first 64 bits:

3ffe:1944:100:a::bc:2500:d0b/64

When you are writing just an IPv6 prefix, you set all the host bits to 0 the same way you do with IPv4 addresses.

For Example:

3ffe:1944:100:a::/64

An IPv6 address consisting of all zeroes can be written simply with a double colon. There are two cases where an all-zeroes address is used. The first is a default address, "Default Routes and On-Demand Routing," in which the address is all zeroes and the prefix length is zero:

::/0

The second all-zeroes IPv6 address is an unspecified address, which is used in some Neighbor Discovery Protocol procedures described later in this chapter. An unspecified address is a filler, indicating the absence of a real IPv6 address. When writing an unspecified address, it is differentiated from a default address by its prefix length:

::/128

IPv6 PREFIXES:

The prefix is the part of the address where the bits have fixed values or are the bits of a route or subnet identifier. Prefixes for IPv6 subnet identifiers and routes are expressed in the same way as Classless Inter-Domain Routing (CIDR) notation for IPv4. An IPv6 prefix is written in address/prefix-length notation.

For example: 21DA:D3::/48 is a route prefix and 21DA:D3:0:2F3B::/64 is a subnet prefix. As described earlier in this chapter, the 64-bit prefix is used for individual subnets to which nodes are attached. All subnets have a 64-bit pre-fix.

Any prefix that is less than 64 bits is a route or address range that is summarizinga portion of the IPv6 address space.

IPV6 ADDRESSES TYPES:

There Are Three Types Of Ipv6 Addresses:

IPv6 has three types of addresses, which can be categorized by type and scope:

• UNICAST ADDRESSES = > A Packet Is Delivered To One Interface.
• MULTICAST ADDRESSES = > A Packet Is Delivered To Multiple Interfaces.
• ANYCAST ADDRESSES = > A Packet Is Delivered To The Nearest Of Multiple Interfaces (In Terms Of Routing Distance).

1. UNICAST A UNICAST ADDRESS identifies a single interface within the scope of the type of address. The scope of an address is the region of the IPv6 network over which the address is unique. With the appropriate unicast routing topology, packets addressed to a unicast address are delivered to a single interface. To accommodate load-balancing systems, RFC 2373 allows for multiple interfaces to use the same address as long as they appear as a single interface to the IPv6 implementation on the host.

2. MULTICAST A MULTICAST ADDRESS identifies zero or more interfaces. With the appropriate multicast routing topology, packets addressed to a multicast address are delivered to all interfaces identified by the address.

3. ANYCAST AN ANYCAST ADDRESS identifies multiple interfaces. With the appropriate unicast routing topology, packets addressed to an anycast address are delivered to a single interface—the nearest interface that is identified by the address. The nearest interface is defined as being the closest in terms of routing distance. A multicast address is used for one-to-many communication, with delivery to multiple interfaces. An anycast address is used for one-to-one-of-many communication, with delivery to a single interface.

Ø NOTE: In all cases, IPv6 addresses identify interfaces, not nodes. A node is identified by any unicast address assigned to any one of its interfaces.

IN ADDITION SPECIAL IPV6 ADDRESSES: The following are special IPv6 addresses:

■ Unspecified address The unspecified address (0:0:0:0:0:0:0:0 or ::) is used only to indicate the absence of an address. It is equivalent to the IPv4 unspecified address of 0.0.0.0. The unspecified address is typically used as a source address when a unique address has not yet been determined. The unspecified address is never assigned to an interface or used as a destination address.

■ Loopback address The loopback address (0:0:0:0:0:0:0:1 or ::1) is used to identify a loopback interface, enabling a node to send packets to itself. It is equivalent to the IPv4 loopback address of 127.0.0.1. Packets addressed to the loopback address must never be sent on a link or forwarded by an IPv6 router.

COMPRESSED IPv6 ADDRESS FORMATS:

Unicast 2001:0:0:0:0DB8:800:200C:417A 2001::0DB8:800:200C:417A

Multicast FF01:0:0:0:0:0:0:101 FF01::101

Loopback 0:0:0:0:0:0:0:1 ::1

Unspecified 0:0:0:0:0:0:0:0 ::

BROADCASTS IN IPV6:

Ø NOTE: Ipv6 Does Not Use Broadcast Messages. (Are Not Used And Replaced By Multicast)

The current set of unicast addresses that can be used with IPv6 nodes consists of aggregatable global unicast addresses, link-local unicast addresses, and site-local unicast addresses. These addresses represent only 12.7 percent of the entire IPv6 address space.

TYPE OF UNICAST IPV6 ADDRESSES:

■ Aggregatable global unicast addresses

■ Link-local addresses

■ LINK / Site-local addresses

■ Special addresses

■ Compatibility addresses

■ NSAP addresses

UNICAST GLOBAL ADDRESSES:

IPv6 unicast global addresses are similar to IPv4 public addresses. Also known as aggregatable global unicast addresses, global addresses are globally routable.

FIELDS IN A UNICAST GLOBAL ADDRESS :

Field	Description
001	Identifies the address as an IPv6 unicast global address.
Top Level Aggregation Identifier (TLA ID)	Identifies the highest level in the routing hierarchy. TLA IDs are administered by IANA, which allocates them to local Internet registries, which then allocate a given TLA ID to a global ISP.
Res	Reserved for future use (to expand either the TLA ID or the NLA ID).
Next Level Aggregation Identifier (NLA ID)	Identifies a specific customer site.
Site Level Aggregation Identifier (SLA ID)	Enables as many as 65,536 (216) subnets within an individual organization’s site. The SLA ID is assigned within the site; an ISP cannot change this part of the address.
Interface ID	Identifies the interface of a node on a specific subnet.

The first 4 bits of the Global unicast address are always 0001 as for this writing.

(2000::/3). The host portion of the address is called the Interface ID. The reason for this

name is that a host can have more than one IPv6 interface, and so the address more

correctly identifies an interface on a host than a host itself.

The public topology is the collection of larger and smaller ISPs that pro-vide access to

the IPv6 Internet. The site topology is the collection of subnets within an organization’s

site. The interface identifier.

LOCAL-USE UNICAST ADDRESSES :

There Are Two Types Of Local-Use Unicast Addresses:

1. Link-Local Addresses Are Used Between On-Link Neighbors And For Neighbor Discovery Processes.

2. Site-Local Addresses Are Used Between Nodes Communicating With Other Nodes In The Same Organization.

UNICAST SITE-LOCAL ADDRESSES:

A site-local address is unique only within a given site; devices in other sites can use the same address. Therefore a site-local address is routable only within the site to which it is assigned.

IPv6 unicast site-local addresses are similar to IPv4 private addresses. The scope of a site-local address is the internetwork of an organization’s site. (You can use both global addresses and site-local addresses in your network.) The prefix for site-local addresses is FEC0::/48.

The following illustration shows the structure of a site-local address.

The initial 48 fixed bits are followed by a 16-bit Subnet ID field, which provides as many as 65,536 subnets in a flat subnet structure. Alternatively, you can subdivide the high-order bits of the Subnet ID field to create a hierarchical routing infrastructure. The last field is a 64-bit Interface ID field that identifies the interface of a node on a specific subnet.

Ø NOTE: Global addresses and site-local addresses share the same structure after the first 48 bits — the 16-bit SLA ID of a global address and the 16-bit Subnet ID of a site-local address both identify the subnets of an organization’s site. Because of this, you can assign a specific subnet number to identify a subnet that is used for both global and site-local unicast addresses.

UNICAST LINK-LOCAL ADDRESSES (FE80::/64):

IPv6 unicast link-local addresses are similar to IPv4 APIPA addresses used by computers running Microsoft Windows. Hosts on the same link (the same subnet) use these automatically configured addresses to communicate with each other. Neighbor Discovery provides address resolution.

A link-local address is an IPv6 unicast address that can be automatically configured on any interface using the link-local prefix FE80::/10 (1111 1110 10) and the interface identifier in the modified EUI-64 format. Link-local addresses are used in the neighbor discovery protocol and the stateless auto configuration process.

UNICAST UNSPECIFIED ADDRESS:

The IPv6 unicast unspecified address is equivalent to the IPv4 unspecified address of 0.0.0.0. The IPv6 unspecified address is 0:0:0:0:0:0:0:0:, or a double colon (::).

UNICAST LOOPBACK ADDRESS:

The IPv6 unicast loopback address is equivalent to the IPv4 loopback address, 127.0.0.1. The IPv6 loopback address is 0:0:0:0:0:0:0:1, or ::1.

MULTICAST IPV6 ADDRESSES:

IPv6 multicast addresses are similar to IPv4 multicast addresses. Packets addressed to a multicast address are delivered to all interfaces that the address identifies.

The following illustration shows the structure of an IPv6 multicast address.

Field	Description
1111 1111	Identifies the address as an IP multicast address.
Flags	Currently, the only defined flag is the Transient (T) flag. Set to zero, the T flag identifies the address as a permanently assigned multicast address. Set to 1, it identifies a transient address.
Scope	Indicates the scope of the multicast traffic, such as interface-local, link-local, site-local, organization-local, or global scope.
Group ID	identifies the multicast group.

MULTICAST SOLICITED NODE ADDRESS:

The IPv6 multicast solicited node address is used for efficient address resolution. The IPv4 ARP Request frame is sent to the MAC-level broadcast, which disturbs all nodes on the network segment. The multicast solicited node address combines the prefix FF02::1:FF00:0/104 with the last 24 bits of the IPv6 address being resolved. IPv6 uses the solicited node multicast address for the Neighbor Solicitation message (the IPv6 equivalent to the ARP Request frame) that resolves an IPv6 address to its link-layer address, disturbing few nodes during the address resolution process.

ANYCAST IPV6 ADDRESSES:

Anycast IPv6 addresses are similar to but more efficient than the anycast addresses in IPv4, which are used primarily by large ISPs. Anycast addresses use the unicast address space but function differently from other unicast addresses. IPv6 uses anycast addresses to identify multiple interfaces.

IPv6 delivers packets addressed to an anycast address to the nearest interface that the address identifies. In contrast to a multicast address, where delivery is from one to many, an anycast address delivery is from one to one-of-many. Currently, anycast addresses are assigned only to routers and are used only as destination addresses.

IPV4-COMPATIBLE IPV6 ADDRESSES:

These address use 0s in the 1^st 96bits, and are used in the transition/migration strategies.

Example: 10.10.100.16 can be represented in IPv6 as:

0:0:0:0:0:10:10:100:16

::10:10:100:16

::A:A:64:10

UNSPECIFIED ADDRESSES

These addresses are used in address auto-configuration & duplicate address detection.

::/128

LOOPBACK ADDRESSES

::1/128

IPV6 FEATURES:

The following are the Advantages of the IPv6 protocol:

* New header format

* Large address space

* Efficient and hierarchical addressing and routing infrastructure

* Stateless and stateful address configuration

* Built-in security

* Better support for QoS

* New protocol for neighboring node interaction

* Extensibilit

IPv6 KEY FEATURES ARE LISTED BELOW:

* Larger address space-An IPv6 address is 128 bit long. Compared with the 32 bit long IPv4 address, this is huge increase in address space.

* Better Header format-IPv6 uses a new header format in which options are separated from the base header and inserted when needed, between the base header and the upper layer data. This simplifies and speeds up the routing process because most of the options do not need to be checked by routers.The IPv6 header has a new format that is designed to keep header overhead to a minimum. This is achieved by moving both non-essential fields and option fields to extension headers that are placed after the IPv6 header. The streamlined IPv6 header provides more efficient processing at intermediate routers.

IPv4 headers and IPv6 headers are not interoperable. A host or router must use an implementation of both IPv4 and IPv6 in order to recognize and process both header formats. The new IPv6 header is only twice as large as the IPv4 header, even though IPv6 addresses are four times as large as IPv4 addresses.

* Larger IP address space. IPv4 uses only 32 bits for IP address space, which allows only 4 billion nodes to be identified on the Internet. 4 billion may look like a large number; however, it is less than the human population on the earth! IPv6 allows 128 bits for IP address space, allowing 340282366920938463463374607431768211456 (three hundred forty undecillion) nodes to be uniquely identified on the Internet.

A larger address space allows true end to end communication, without NAT or other short term workarounds against the IPv4 address shortage. (These days NAT is a headache for new protocol deployment and has scalability issues; we really need to decommission NAT networks for the Internet to grow further).

Deploy more recent technologies. After IPv4 was specified 20 years ago, we saw many technical improvements in networking. IPv6 includes a number of those improvements in its base specification, allowing people to assume these features are available everywhere, anytime. "Recent technologies" include, but are not limited to, the following:

o Autoconfiguration. With IPv4, DHCP exists but is optional. A novice user can get into trouble if they visit another site without a DHCP server. With IPv6, a "stateless host autoconfiguration" mechanism is mandatory. This is much simpler to use and manage than IPv4 DHCP. RFC2462 has the specification for it.

o Security. With IPv4, IPsec is optional and you need to ask the peer if it supports IPsec. With IPv6, IPsec support is mandatory. By mandating IPsec, we can assume that you can secure your IP communication whenever you talk to IPv6 devices.

o Friendly to traffic engineering technologies. IPv6 was designed to allow better support for traffic engineering like diffserv or intserv (RSVP). We do not have a single standard for traffic engineering yet, so the IPv6 base specification reserves a 24-bit space in the header field for those technologies and is able to adapt to coming standards better than IPv4.

o Multicast. Multicast is mandatory in IPv6, which was optional in IPv4. The IPv6 base specifications themselves extensively use multicast.

o Better support for ad-hoc networking. Scoped addresses allow better support for ad-hoc (or "zeroconf") networking. IPv6 supports anycast addresses, which can also contribute to service discoveries.

* A cure to routing table growth. The IPv4 backbone routing table size has been a big headache to ISPs and backbone operators. The IPv6 addressing specification restricts the number of backbone routing entries by advocating route aggregation. With the current IPv6 addressing specification, we will see only 8192 routes on the default-free zone.

* Simplified header structures. IPv6 has simpler packet header structures than IPv4. It will allow future vendors to implement hardware acceleration for IPv6 routers easier.

* Allows flexible protocol extensions. IPv6 allows more flexible protocol extensions than IPv4 does, by introducing a protocol header chain. Even though IPv6 allows flexible protocol extensions, IPv6 does not impose overhead to intermediate routers. It is achieved by splitting headers into two flavors: the headers intermediate routers need to examine, and the headers the end nodes will examine. This also eases hardware acceleration for IPv6 routers.

* Smooth transition from IPv4. There were number of transition considerations made during the IPv6 discussions. Also, there are large number of transition mechanisms available. You can pick the most suitable one for your site.

* Follows the key design principles of IPv4. IPv4 was a very successful design, as proven by the ultra large-scale global deployment. IPv6 is "new version of IP", and it follows many of the design features that made IPv4 very successful. This will also allow smooth transition from IPv4 to IPv6.

IPv6 ON CISCO ROUTERS:

Implementing basic IPv6 connectivity in the Cisco IOS software consists of assigning IPv6 addresses to individual router interfaces. The forwarding of IPv6 traffic can be enabled globally, and Cisco Express Forwarding switching for IPv6 can also be enabled. Basic connectivity can be enhanced by configuring support for AAAA record types in the Domain Name System (DNS) name-to-address and address-to-name lookup processes, and by managing IPv6 neighbor discovery.

Cisco Has Already Developed Extensions To Ipv4, Incorporating In Ipv4 Many Of The Advantages Of Ipv6.

FOR EXAMPLE:

Ø Classless Inter-Domain Routing (CIDR) and Network Address Translation (NAT) provide an effective means of resolving the current limitations of IP address assignment.

Ø Virtual Private Networks (VPNs) made with IPv4 tunnels are an effective solution for Enterprise networks and when integrated with NAT mitigate the lack of IPv4 address space.

Ø IPSec available in IPv4 addresses the security concerns of network managers.

Ø DHCP servers and relays address the need for user mobility and for plug-and-play configuration.

Ø Resource Reservation Protocol (RSVP) and Weighted Fair Queuing (WFQ) are among the options available for defining quality of service on existing IP networks.

Cisco recognises that continued growth of the Internet and demand for IP addressing will be fueled for example by the Voice over IP (VoIP), the new on-line devices such as Personal Digital Assistants (PDAs), hybrid mobile phones, and set-top boxes, all of which are becoming Networkaware and IP manageable and as such IPv6 provides a clear path to such expansion.

Of course, there are also some caveat and inefficiencies introduced by IPv6: while the regular and simple structure of the IPv6 header will simplify the streamline processing of packets without options, the larger header size will no longer make possible to fully contain a TCP ACK response in a single ATM cell (as in IPv4)—introducing a substantial overhead.

Another important advantage of IPv6 is the provider-based addressing, that will introduce an efficient aggregation hierarchy with the related benefits (there is a clear analogy with telephony network). With the current proposal of Top-Level Aggregator, Next-Level Aggregator, Site-Level Aggregator, etc., it is possible that the Internet core router would carry only 8,000 prefixes on the Internet backbone.

Cisco’s strategy is to minimize the transition pain and leverage existing proven technology, like translation. The most likely deployment scenario will see the Enterprise first with Cisco routers performing translation for the backbone Internet until a major ISP seeks first-mover advantage.

Going forward, Cisco understands that both IPv4/NAT and IPv6 will coexist for a long period of time and, therefore, it is ready to support both of them in an integrated way in IOS.

SYMPLE STEPS FOR IPv6 CONFIGURATION ON CISCO ROUTER:

Enable Ipv6 On Router (By Default Is Turned Off)

Router(Config)#Ipv6 Unicast-Routing Enable Cisco Cef Router(Config)#Ipv6 Cef Then Configure Interface With Ipv6 Address

Router(Config-If)#Ipv6 Address Ipv6-Address/Prefix-Length [Eui-64] Example:

Router#Configure Terminal

Router(Config)#Ipv6 Unicast-Routing Router(Config)#Ipv6 Cef

Router(Config)#Interface Fastethernet0/0

Router(Config-If)#Description Local Lan Router(Config-If)#Ipv6 Address 2001:0:1:1::2/64

SYMPLE LAB STEPS:

We have three routers such as 2811 A Router, 2811B Router, 2811C Router Connect with each other’s.

1. Enable IPv6 routing and Cisco Express Forwarding (CEF) on each router.

2811A ROUTER#config t 2811A ROUTER(config)#ipv6 unicast-routing 2811A ROUTER(config)#ipv6 cef

2811B ROUTER#config t 2811B ROUTER(config)#ipv6 unicast-routing 2811B ROUTER(config)#ipv6 cef

2811C ROUTER#config t 2811C ROUTER(config)#ipv6 unicast-routing 2811C ROUTER(config)#ipv6 cef

2. Configure IPv6 addresses on router 2811 A ROUTER.

2811A ROUTER (config)#interface fastethernet 0/0 2811A ROUTER (config-if)#ipv6 address 2001::10:1/112

2811A(config-if)#interface serial 0/0/0 2811A(config-if )ipv6 address 2001::20:1/112

2811A(config-if)#interface serial 0/1/0 2811A(config-if)#ipv6 address 2001::30:1/112

2811A(config-if)#exit

3. Configure IPv6 addresses on router 2811 B ROUTER.

2811B(config)#interface fastethernet 0/0 2811B(config-if)# ipv6 address 2001::40:1/112

2811B(config-if)#interface serial 0/1/0 2811B(config-if)#ipv6 address 2001::30:2/112 2811B(config-if)#exit

4. Configure IPv6 addresses on router 2811 C ROUTER.

2811C(config)#interface fastethernet 0/0 2811C(config-if)# ipv6 address 2001::50:1/112

2811C(config-if)#interface serial 0/0/0 2811C(config-if)#ipv6 address 2001::20:2/112

2811C(config-if)#exit

5. Configure two IPv6 static routes on router 2811 A ROUTER.

2811A(config)#ipv6 route 2001::40:0/112 2001::30:2 2811A(config)#ipv6 route 2001::50:0/112 2001::20:2 2811A(config)#exit 2811A#copy run start

The static routes will allow router 2811 A ROUTER to communicate with the rest of the network.

6. Configure a IPv6 default route on router 2811 B.

2811B(config)#ipv6 route ::/0 2001::30:1 2811B(config)#exit 2811B#copy run start

This default route will allow router 2811 B ROUTER to communicate with the rest of the network. Router 2811 B ROUTER will use router 2811 A ROUTER as a gateway of last resort.

7. Configure a IPv6 default route on router 2811 C.

2811C(config)#ipv6 route ::/0 2001::20:1 2811C(config)#exit 2811C#copy run start

This Default Route Will Allow Router 2811 C ROUTER To Communicate With The Rest Of The Network. Router 2811 C ROUTER Will Use Router 2811 A ROUTER As A Gateway Of Last Resort.

ALSO KNOW CISCO - IPv6 COMMANDS:

Let’s examine the most relevant commands also the output of some show commands.

show ipv6 route

Cis Rou >show ipv6 route

This command displays the IPv6 routing table.

show ipv6 tunnel

Cis Rou >show ipv6 tunnel

This command displays, for each tunnel running IPv6, the tunnel unit number, the name of the dynamic routing protocol in use, the time of the last input, the number of input packets, and the description string.

show ipv6 neighbors

show ipv6 neighbors [ | ]

This command displays neighbor adjacency entries from the IPv6 Neighbor Discovery (ND) table. It includes the state of the adjacency entry, its lifetime, and the associated MAC and IPv6 addresses.

Cis Rou >show ipv6 neighbors

show ipv6 interface

show ipv6 interface []

This command displays IPv6 interface related parameters and addresses.

Cis Rou> show ipv6 int FastEthernet0/0/0

show ipv6 traffic

show ipv6 traffic

This command displays IPv6 related traffic statistics.

traceroute ipv6

traceroute ipv6

This command traces the route for IPv6 packets between the node where the command is entered and the destination address.

ping ipv6

ping ipv6

This command sends ICMPv6 echo request packets to , i.e., to an IPv6 host name or address.

ipv6 unicast-routing

ipv6 unicast-routing

This command enables the routing of IPv6 unicast packets. The default setting is disabled.

interface tunnel

interface tunnel

Tunneling provides a way to encapsulate arbitrary packets inside another Protocol. It is implemented as a virtual interface to provide a simple configuration. In the preceding example it is used to create an IPv6 tunnel over IPv4.

The IPv4 end-points are specified with the commands:

• tunnel source
• tunnel destination

Because tunnels are point-to-point links, a separate tunnel is configured

for each link.

The command no ip address specifies that there is no IPv4 address associated to this tunnel, while the command ipv6 address assigns an IPv6 address to the tunnel interface. Finally, the command tunnel mode ipv6ip configures a static tunnel interface (a “configured tunnel” according to RFC 1933 [1]).

This interface can be used like any other interface (static routes can point to it or a dynamic routing protocol can run over it).

ipv6 address

[no] ipv6 address [/]

This command enables IPv6 and configures an IPv6 address on the interface. Optionally, a prefix length may be specified. In this case the router will autoconfigure the remaining bits.

ipv6 address ... eui-64

[no] ipv6 address / eui-64

This command is used to enable IPv6 and to autoconfigure an IPv6 address on an interface using the EUI-64 style “Interface ID”.

If the specified is greater than 64, the prefix bits

will have precedence over the EUI-64 ID.

ipv6 unnumbered

[no] ipv6 unnumbered

It is also possible to enable and to configure an interface without requiring a global IPv6 address. The parameter must specify the name of an interface that does have a global IPv6 address. This command is used to reduce address administration for a network administrator

ipv6 route

[no] ipv6 route { | } []

This command configures a static IPv6 route. specifies the IPv6 prefix for which the route is created. is the host name or IPv6 address of the next-hop to reach the destination prefix. can be used in place of for point-to-point interfaces like serial links or tunnels.

The default value for is 1, which gives static routes precedence over any other type of route with the exception of directly connected routes.

ipv6 mtu

[no] ipv6 mtu

This command configures the Maximum Transmission Unit (MTU) for IPv6 packets on an interface. The default value is the link MTU. If a nondefault value is configured, an MTU option will be included in Router Advertisements (see Section 5.6.5).

ipv6 hop-limit

ipv6 hop-limit

This command configures the router to use as the IPv6 Hop Limit value used in Router Advertisements and in all IPv6 packets generated within the router. The default value is 255.

ipv6 auto-tunnel

[no] ipv6 auto-tunnel

This command configures IPv6 in IPv4 automatic tunneling (see RFC 1933 [1]). Automatic tunneling is performed when a destination address in an IPv6 packet contains an IPv4 compatible IPv6 address

RIP PROTOCOL:

The Cisco implementation of IPv6 supports RIPv6. RIP routing is started whenever RIP is enabled on at least one interface. It is also possible to redistribute static routes over RIP.

BGP4+:

To configure BGP4+ it is therefore necessary first to configure and start the IPv4 BGP with the classical command:

router bgp

The definition of IPv6 neighbors and parameters is however done in a different section of the configuration file. The principal commands used are described in the following sections.

ipv6 bgp redistribute connected

[no] ipv6 bgp redistribute connected

This command configures the redistribution of routing information learned on directly connected networks into bgp.

ipv6 bgp redistribute static

[no] ipv6 bgp redistribute static

This command configures the redistribution of static routes into bgp.

ipv6 bgp redistribute rip

[no] ipv6 bgp redistribute rip

This command configures the redistribution of routes learned via rip

process into bgp.

ipv6 bgp neighbor

ipv6 bgp neighbor remote-as

no ipv6 bgp neighbor remote-as

This command defines a BGP neighbor. External neighbors must be directly connected. Neighbors must be specified by global addresses.

ipv6 bgp network

[no] ipv6 bgp network

This command originates a BGP route for each route found on the IPv6 routing table that matches with the given prefix.

ALSO OSPFv3 CONFIGURATION EXAMPLE:

FOR SYMPLE OSPF EXAMPLE: WE HAVE ROUTER 1 & ROUTER 2 AND ROUTER 1 INTERFACES ARE CONNECTED WITH:

Ø ROUTER Eth0 CONNECTED - LAN1: 2001:1:1:1::/64 - Area 0 (ROUTER 2)

Ø ROUTER Eth1 CONNECTED - LAN2: 2001:2:2:2::/64 - Area 1

Router1

EXAMPLE ROUTER#

interface Ethernet0

ipv6 address 2001:1:1:1::1/64

ipv6 ospf 1 area 0

interface Ethernet1

ipv6 address 2001:2:2:2::2/64

ipv6 ospf 1 area 1

ipv6 router ospf 1

router-id 1.1.1.1

area 1 range 2001:2:2::/48

Router 2# show ipv6 route ospf

IPv6 Routing Table - 9 entries

Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP

U - Per-user Static route

I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea

O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2

O 2001:1:1:2::1/128 [110/1]

via FE80::205:5FFF:FEAF:2C38, Ethernet0

OI 2001:2:2::/48 [110/2]

via FE80::205:5FFF:FEAF:2C38, Ethernet0

THEN:

Router2# show ipv6 ospf database

OSPF3 - LAB EXAMPLE:

• Configure R1, R2 and R3′s OSPFv3 Router-ID according to their router number. I.e; 1.1.1.1
• Configure R1′s Serial1/0.122 & R2′s Serial1/0.221 interfaces to participate in OSPF Area 0.
• Configure R2′s Serial1/0.223 & R3′s Serial1/0.322 interfaces to participate in OSPF Area 0.
• Configure R1′s Loopback0 interface to participate in OSPF Area 1 and ensure that R1 advertises Lo0 as a /64 subnet and not a host route (/128).
• Configure R2′s Loopback0 interface to participate in OSPF Area 2 and ensure that R1 advertises Lo0 as a /64 subnet and not a host route (/128).
• Configure R2′s Loopback0 interface to participate in OSPF Area 3 and ensure that R1 advertises Lo0 as a /64 subnet and not a host route (/128).
• Verify that R1′s Loopback0 network is in the IPv6 routing table of R3.
• Verify that R3′s Loopback0 network has IPv6 connectivity to R1′s Loopback0 network using PING.

LAB INSTRUCTION:

Objective 1. – Configure R1, R2 and R3′s OSPFv3 Router-ID according to their router number.

R1>enable R1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. R1(config)#ipv6 unicast-routing R1(config)#ipv6 router ospf 1 R1(config-rtr)#router-id 1.1.1.1 R1(config-rtr)#exit R1(config)#

R2>enable R2#configure terminal Enter configuration commands, one per line. End with CNTL/Z. R2(config)#ipv6 unicast-routing R2(config)#ipv6 router ospf 1 R2(config-rtr)#router-id 2.2.2.2 R2(config-rtr)#exit R2(config)#

R3>enable R3#configure terminal Enter configuration commands, one per line. End with CNTL/Z. R3(config)#ipv6 unicast-routing R3(config)#ipv6 router ospf 1 R3(config-rtr)#router-id 3.3.3.3 R3(config-rtr)#exit R3(config)#

Objective 2. – Configure R1′s Serial1/0.122 & R2′s Serial1/0.221 interfaces to participate in OSPF Area 0.

R1(config)#interface Serial1/0.122 R1(config-subif)#ipv6 ospf 1 area 0 R1(config-subif)#exit R1(config)#

R2(config)#interface s1/0.221 R2(config-subif)#ipv6 ospf 1 area 0 R2(config-subif)# %OSPFv3-5-ADJCHG: Process 1, Nbr 1.1.1.1 on Serial1/0.221 from LOADING to FULL, Loading Done R2(config-subif)#exit R2(config)#

Objective 3. – Configure R2′s Serial1/0.223 & R3′s Serial1/0.322 interfaces to participate in OSPF Area 0.

R2(config)#interface Serial1/0.223 R2(config-subif)#ipv6 ospf 1 area 0 R2(config-subif)#exit R2(config)#

R3(config)#interface Serial1/0.322 R3(config-subif)#ipv6 ospf 1 area 0 R3(config-subif)#exit R3(config)# %OSPFv3-5-ADJCHG: Process 1, Nbr 2.2.2.2 on Serial1/0.322 from LOADING to FULL, Loading Done R3(config)#

Objective 4. – Configure R1′s Loopback0 interface to participate in OSPF Area 1 and ensure that R1 advertises Lo0 as a /64 subnet and not a host route (/128).

NOTE: Loopback interfaces have their own OSPF network type in which case OSPF advertises a host route to the loopback interface and not the configure subnet mask.

To change OSPF to advertise the subnet assigned to the loopback interface you’ll need to change the network type to point-to-point as shown below;

R1(config)#interface loopback0 R1(config-if)#ipv6 ospf 1 area 1 R1(config-if)#ipv6 ospf network point-to-point R1(config-if)#end R1# %SYS-5-CONFIG_I: Configured from console by console R1#

Objective 5. – Configure R2′s Loopback0 interface to participate in OSPF Area 2 and ensure that

R1 advertises Lo0 as a /64 subnet and not a host route (/128).

R2(config)#interface loopback0 R2(config-if)#ipv6 ospf 1 area 2 R2(config-if)#ipv6 ospf network point-to-point R2(config-if)#end R2# %SYS-5-CONFIG_I: Configured from console by console R2#

Objective 6. – Configure R3′s Loopback0 interface to participate in OSPF Area 3 and ensure that R1 advertises Lo0 as a /64 subnet and not a host route (/128).

R3(config)#interface loopback0 R3(config-if)#ipv6 ospf 1 area 3 R3(config-if)#ipv6 ospf network point-to-point R3(config-if)#end R3# %SYS-5-CONFIG_I: Configured from console by console R3#

Objective 7. – Verify that R1′s Loopback0 network is in the IPv6 routing table of R3.

\R3#show ipv6 route ospf IPv6 Routing Table - Default - 8 entries Codes: C - Connected, L - Local, S - Static, U - Per-user Static route B - BGP, M - MIPv6, R - RIP, I1 - ISIS L1 I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary, D - EIGRP EX - EIGRP external O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2 ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2 OI 2001:ABAD:BEEF:1001::/64 [110/129] via FE80::C800:DFF:FE0C:8, Serial1/0.322 O 2001:ABAD:BEEF:1221::/64 [110/128] via FE80::C800:DFF:FE0C:8, Serial1/0.322 OI 2001:ABAD:BEEF:2002::1/128 [110/64] via FE80::C800:DFF:FE0C:8, Serial1/0.322 R3#

Objective 8. – Verify that R3′s Loopback0 network has IPv6 connectivity to R1′s Loopback0 network using PING.

R3#ping 2001:ABAD:BEEF:1001::1 source loopback0 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001:ABAD:BEEF:1001::1, timeout is 2 seconds: Packet sent with a source address of 2001:ABAD:BEEF:3003::1 !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 8/41/104 ms R3#

EMBEDDED IPV4 ADDRESSES: There are several transition technologiesmeans of helping to transition a network from IPv4 to IPv6 or otherwise help IPv4 and IPv6 to coexistthat require an IPv4 address to be communicated within an IPv6 address. The individual technology specifies how the IPv4 address is to be embedded in the IPv6 address, and the implementation of the technology knows where among the 128 bits of the IPv6 address to find the 32 bits of the IPv4 address. But you will also find that many of these technologies have unique formats for their address representations that allow you to identify the embedded IPv4 address. Examples: of IPv6 addresses with an embedded IPv4 address of 10.23.1.5 are: FE80::5EfE:10.23.1.5 (An ISATAP address) ::FFFF:10.23.1.5 and ::FFFF:0:10.23.1.5 (SIIT addresses) FEC0:0:0:1::10.23.1.5 (TRT address) In each of these examples, the IPv4 address is the last 32 bits of the IPv6 address and is represented in dotted decimal. Other transition technologies using embedded IPv4 addresses do not use dotted decimal but encode the IPv4 address into hexadecimal. 6to4, for example, does this. 10.23.1.5 in hexadecimal is 0A17:0105. A 6to4 prefix with 10.23.1.5 embedded is then 2002:0A17:0105::/48 Transition technologies are not covered in this volume, and so you are not likely to see one of these address representations again in this book. They are shown here only because you are likely to encounter addresses like these if you work with IPv6.

For More Inf4 = >

Ø http://www.cisco.com/en/US/docs/ios/ipv6/configuration/guide/ip6-addrg_bsc_con.html

CONCLUSION:

The Goal Of This Article Is To Give An Easy Way To Understand Basic IPv6 And I Hope This Article It May Helps Every One. Thank You!

This Article Written Author By: Premakumar Thevathasan. CCNA, CCNP, CCIP, MCSE, MCSA, MCSA - MSG, CIW Security Analyst, CompTIA Certified A+.