Category: ipv6

IPv6 Tutorial PDF Version Quick Guide Resources Job Search Discussion Internet Protocol version 6 (IPv6) is the latest revision of the Internet Protocol (IP) and the first version of the protocol to be widely deployed. IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the long-anticipated problem of IPv4 address exhaustion. This tutorial will help you in understanding IPv6 and its associated terminologies along with appropriate references and examples. Audience This tutorial has been designed to help beginners understand the basic concepts of IPv6 required to work with any TCP/IP based protocols. After completing this tutorial you will find yourself at a moderate level of expertise of IPv6 from where you can take yourself to next levels. Prerequisites Before you start proceeding with this tutorial, we are assuming that you are already aware of basic computer and network concepts such as what is a protocol, why do we need protocol, network layers, etc. Print Page Previous Next Advertisements ”;

IPv6 – Communication ”; Previous Next In IPv4, a host that wants to communicate with another host on the network needs to have an IP address acquired either by means of DHCP or by manual configuration. As soon as a host is equipped with some valid IP address, it can speak to any host on the subnet. To communicate on layer-3, a host must also know the IP address of the other host. Communication on a link, is established by means of hardware embedded MAC Addresses. To know the MAC address of a host whose IP address is known, a host sends ARP broadcast and in return, the intended host sends back its MAC address. In IPv6, there are no broadcast mechanisms. It is not a must for an IPv6 enabled host to obtain an IP address from DHCP or manually configured, but it can auto-configure its own IP. ARP has been replaced by ICMPv6 Neighbor Discovery Protocol. Neighbor Discovery Protocol A host in IPv6 network is capable of auto-configuring itself with a unique link-local address. As soon as host gets an IPv6 address, it joins a number of multicast groups. All communications related to that segment take place on those multicast addresses only. A host goes through a series of states in IPv6: Neighbor Solicitation: After configuring all IPv6’s either manually, or by DHCP Server or by auto-configuration, the host sends a Neighbor Solicitation message out to FF02::1/16 multicast address for all its IPv6 addresses in order to know that no one else occupies the same addresses. DAD (Duplicate Address Detection): When the host does not listen from anything from the segment regarding its Neighbor Solicitation message, it assumes that no duplicate address exists on the segment. Neighbor Advertisement: After assigning the addresses to its interfaces and making them up and running, the host once again sends out a Neighbor Advertisement message telling all other hosts on the segment, that it has assigned those IPv6 addresses to its interfaces. Once a host is done with the configuration of its IPv6 addresses, it does the following things: Router Solicitation: A host sends a Router Solicitation multicast packet (FF02::2/16) out on its segment to know the presence of any router on this segment. It helps the host to configure the router as its default gateway. If its default gateway router goes down, the host can shift to a new router and makes it the default gateway. Router Advertisement: When a router receives a Router Solicitation message, it response back to the host, advertising its presence on that link. Redirect: This may be the situation where a Router receives a Router Solicitation request but it knows that it is not the best gateway for the host. In this situation, the router sends back a Redirect message telling the host that there is a better ‘next-hop’ router available. Next-hop is where the host will send its data destined to a host which does not belong to the same segment. Print Page Previous Next Advertisements ”;

IPv6 – Headers ”; Previous Next The wonder of IPv6 lies in its header. An IPv6 address is 4 times larger than IPv4, but surprisingly, the header of an IPv6 address is only 2 times larger than that of IPv4. IPv6 headers have one Fixed Header and zero or more Optional (Extension) Headers. All the necessary information that is essential for a router is kept in the Fixed Header. The Extension Header contains optional information that helps routers to understand how to handle a packet/flow. Fixed Header [Image: IPv6 Fixed Header]IPv6 fixed header is 40 bytes long and contains the following information. S.N. Field & Description 1 Version (4-bits): It represents the version of Internet Protocol, i.e. 0110. 2 Traffic Class (8-bits): These 8 bits are divided into two parts. The most significant 6 bits are used for Type of Service to let the Router Known what services should be provided to this packet. The least significant 2 bits are used for Explicit Congestion Notification (ECN). 3 Flow Label (20-bits): This label is used to maintain the sequential flow of the packets belonging to a communication. The source labels the sequence to help the router identify that a particular packet belongs to a specific flow of information. This field helps avoid re-ordering of data packets. It is designed for streaming/real-time media. 4 Payload Length (16-bits): This field is used to tell the routers how much information a particular packet contains in its payload. Payload is composed of Extension Headers and Upper Layer data. With 16 bits, up to 65535 bytes can be indicated; but if the Extension Headers contain Hop-by-Hop Extension Header, then the payload may exceed 65535 bytes and this field is set to 0. 5 Next Header (8-bits): This field is used to indicate either the type of Extension Header, or if the Extension Header is not present then it indicates the Upper Layer PDU. The values for the type of Upper Layer PDU are same as IPv4’s. 6 Hop Limit (8-bits): This field is used to stop packet to loop in the network infinitely. This is same as TTL in IPv4. The value of Hop Limit field is decremented by 1 as it passes a link (router/hop). When the field reaches 0 the packet is discarded. 7 Source Address (128-bits): This field indicates the address of originator of the packet. 8 Destination Address (128-bits): This field provides the address of intended recipient of the packet. Extension Headers In IPv6, the Fixed Header contains only that much information which is necessary, avoiding those information which is either not required or is rarely used. All such information is put between the Fixed Header and the Upper layer header in the form of Extension Headers. Each Extension Header is identified by a distinct value. When Extension Headers are used, IPv6 Fixed Header’s Next Header field points to the first Extension Header. If there is one more Extension Header, then the first Extension Header’s ‘Next-Header’ field points to the second one, and so on. The last Extension Header’s ‘Next-Header’ field points to the Upper Layer Header. Thus, all the headers points to the next one in a linked list manner. If the Next Header field contains the value 59, it indicates that there are no headers after this header, not even Upper Layer Header. The following Extension Headers must be supported as per RFC 2460: The sequence of Extension Headers should be: These headers: 1. should be processed by First and subsequent destinations. 2. should be processed by Final Destination. Extension Headers are arranged one after another in a linked list manner, as depicted in the following diagram: [Image: Extension Headers Connected Format] Print Page Previous Next Advertisements ”;

IPv6 – Routing ”; Previous Next Routing concepts remain same in case of IPv6 but almost all routing protocols have been redefined accordingly. We discussed earlier, how a host speaks to its gateway. Routing is a process to forward routable data choosing the best route among several available routes or path to the destination. A router is a device that forwards data that is not explicitly destined to it. There exists two forms of routing protocols: Distance Vector Routing Protocol: A router running distance vector protocol advertises its connected routes and learns new routes from its neighbors. The routing cost to reach a destination is calculated by means of hops between the source and destination. A router generally relies on its neighbor for best path selection, also known as “routing-by-rumors”. RIP and BGP are Distance Vector Protocols. Link-State Routing Protocol: This protocol acknowledges the state of a Link and advertises to its neighbors. Information about new links is learnt from peer routers. After all the routing information has been converged, the Link-State Routing Protocol uses its own algorithm to calculate the best path to all available links. OSPF and IS-IS are link state routing protocols and both of them use Dijkstra’s Shortest Path First algorithm. Routing protocols can be divided in two categories: Interior Routing Protocol: Protocols in this categories are used within an autonomous system or organization to distribute routes among all routers inside its boundary. Examples: RIP, OSPF. Exterior Routing Protocol: An Exterior Routing Protocol distributes routing information between two different autonomous systems or organization. Examples: BGP. Routing protocols RIPng RIPng stands for Routing Information Protocol Next Generation. This is an Interior Routing Protocol and is a Distance Vector Protocol. RIPng has been upgraded to support IPv6. OSPFv3 Open Shortest Path First version 3 is an Interior Routing Protocol which is modified to support IPv6. This is a Link-State Protocol and uses Djikrasta’s Shortest Path First algorithm to calculate best path to all destinations. BGPv4 BGP stands for Border Gateway Protocol. It is the only open standard Exterior Gateway Protocol available. BGP is a Distance Vector protocol which takes Autonomous System as calculation metric, instead of the number of routers as Hop. BGPv4 is an upgrade of BGP to support IPv6 routing. Protocols Changed to Support IPv6 ICMPv6: Internet Control Message Protocol version 6 is an upgraded implementation of ICMP to accommodate IPv6 requirements. This protocol is used for diagnostic functions, error and information message, statistical purposes. ICMPv6’s Neighbor Discovery Protocol replaces ARP and helps discover neighbor and routers on the link. DHCPv6: Dynamic Host Configuration Protocol version 6 is an implementation of DHCP. IPv6 enabled hosts do not require any DHCPv6 Server to acquire IP address as they can be auto-configured. Neither do they need DHCPv6 to locate DNS server because DNS can be discovered and configured via ICMPv6 Neighbor Discovery Protocol. Yet DHCPv6 Server can be used to provide these information. DNS: There has been no new version of DNS but it is now equipped with extensions to provide support for querying IPv6 addresses. A new AAAA (quad-A) record has been added to reply IPv6 query messages. Now the DNS can reply with both IP versions (4 & 6) without any change in the query format. Print Page Previous Next Advertisements ”;

IPv6 – Summary ”; Previous Next IPv4 since 1982, has been an undisputed leader of Internet. With IPv4’s address space exhaustion, IPv6 is now taking over the control of Internet, which is called Internet2. IPv4 is widely deployed and migration to IPv6 would not be easy. So far IPv6 could penetrate IPv4’s address space by less than 1%. The world has celebrated ‘World IPv6 Day’ on June 08, 2011 with a purpose to test IPv6 address over Internet in full. On June 06, 2012 the Internet community officially launched IPv6. This day all ISPs who were offering IPv6 were to enable it on public domain and were to keep it enable. All the device manufacturer also participated to offer IPv6 by-default enabled on devices. This was a step towards encouraging Internet community to migrate to IPv6. Organizations are provided plenty of ways to migrate from IPv4 to IPv6. Also organizations, willing to test IPv6 before migrating completely can run both IPv4 and IPv6 simultaneously. Networks of different IP versions can communicate and user data can be tunneled to walk to the other side. Future of IPv6 IPv6 enabled Internet version 2 will replace todays IPv4 enabled Internet. When Internet was launched with IPv4, developed countries like U.S. and Europe took the larger space of IPv4 for deployment of Internet in their respective countries keeping future need in mind. But Internet exploded everywhere reaching and connecting every country of the world increasing the requirement of IPv4 address space. As a result, till this day U.S. and Europe have many IPv4 address space left with them and countries like India and China are bound to address their IP space requirement by means of deployment of IPv6. Most of the IPv6 deployment is being done outside U.S., and Europe. India and China are moving forward to change their entire space to IPv6. China has announced a five year deployment plan named China Next Generation Internet. After June 06, 2012 all major ISPs were shifted to IPv6 and rest of them are still moving. IPv6 provides ample of address space and is designed to expand today’s Internet services. Feature-rich IPv6 enabled Internet version 2 may deliver more than expected. Print Page Previous Next Advertisements ”;

IPv6 – Mobility ”; Previous Next When a host is connected to a link or network, it acquires an IP address and all communication take place using that IP address on that link. As soon as, the same host changes its physical location, that is, moves into another area / subnet / network / link, its IP address changes accordingly, and all the communication taking place on the host using old IP address, goes down. IPv6 mobility provides a mechanism for the host to roam around different links without losing any communication/connection and its IP address. Multiple entities are involved in this technology: Mobile Node: The device that needs IPv6 mobility. Home Link: This link is configured with the home subnet prefix and this is where the Mobile IPv6 device gets its Home Address. Home Address: This is the address which the Mobile Node acquires from the Home Link. This is the permanent address of the Mobile Node. If the Mobile Node remains in the same Home Link, the communication among various entities take place as usual. Home Agent: This is a router that acts as a registrar for Mobile Nodes. Home Agent is connected to Home Link and maintains information about all Mobile Nodes, their Home Addresses, and their present IP addresses. Foreign Link: Any other Link that is not Mobile Node’s Home Link. Care-of Address: When a Mobile Node gets attached to a Foreign Link, it acquires a new IP address of that Foreign Link’s subnet. Home Agent maintains the information of both Home Address and Care-of Address. Multiple Care-of addresses can be assigned to a Mobile Node, but at any instance, only one Care-of Address has binding with the Home Address. Correspondent Node: Any IPv6 enabled device that intends to have communication with Mobile Node. Mobility Operation When Mobile Node stays in its Home Link, all communications take place on its Home Address as shown below: [Image: Mobile Node connected to Home Link]When a Mobile Node leaves its Home Link and is connected to some Foreign Link, the Mobility feature of IPv6 comes into play. After getting connected to a Foreign Link, the Mobile Node acquires an IPv6 address from the Foreign Link. This address is called Care-of Address. The Mobile Node sends a binding request to its Home Agent with the new Care-of Address. The Home Agent binds the Mobile Node’s Home Address with the Care-of Address, establishing a Tunnel between both. Whenever a Correspondent Node tries to establish connection with the Mobile Node (on its Home Address), the Home Agent intercepts the packet and forwards to Mobile Node’s Care-of Address over the Tunnel which was already established. [Image: Mobile Node connected to Foreign Link]Route Optimization When a Correspondent Node initiates a communication by sending packets to Mobile the Node on the Home Address, these packets are tunneled to the Mobile Node by the Home Agent. In Route Optimization mode, when the Mobile Node receives a packet from the Correspondent Node, it does not forward replies to the Home Agent. Rather, it sends its packet directly to the Correspondent Node using Home Address as Source Address. This mode is optional and not used by default. Print Page Previous Next Advertisements ”;

IPv6 – Quick Guide ”; Previous Next Overview Internet Protocol version 6, is a new addressing protocol designed to incorporate whole sort of requirement of future internet known to us as Internet version 2. This protocol as its predecessor IPv4, works on Network Layer (Layer-3). Along with its offering of enormous amount of logical address space, this protocol has ample of features which addresses today’s shortcoming of IPv4. Why new IP version? So far, IPv4 has proven itself as a robust routable addressing protocol and has served human being for decades on its best-effort-delivery mechanism. It was designed in early 80’s and did not get any major change afterward. At the time of its birth, Internet was limited only to a few Universities for their research and to Department of Defense. IPv4 is 32 bits long which offers around 4,294,967,296 (232) addresses. This address space was considered more than enough that time. Given below are major points which played key role in birth of IPv6: Internet has grown exponentially and the address space allowed by IPv4 is saturating. There is a requirement of protocol which can satisfy the need of future Internet addresses which are expected to grow in an unexpected manner. Using features such as NAT, has made the Internet discontiguous i.e. one part which belongs to intranet, primarily uses private IP addresses; which has to go through number of mechanism to reach the other part, the Internet, which is on public IP addresses. IPv4 on its own does not provide any security feature which is vulnerable as data on Internet, which is a public domain, is never safe. Data has to be encrypted with some other security application before being sent on Internet. Data prioritization in IPv4 is not up to date. Though IPv4 has few bits reserved for Type of Service or Quality of Service, but they do not provide much functionality. IPv4 enabled clients can be configured manually or they need some address configuration mechanism. There exists no technique which can configure a device to have globally unique IP address. Why not IPv5? Till date, Internet Protocol has been recognized has IPv4 only. Version 0 to 3 were used while the protocol was itself under development and experimental process. So, we can assume lots of background activities remain active before putting a protocol into production. Similarly, protocol version 5 was used while experimenting with stream protocol for internet. It is known to us as Internet Stream Protocol which used Internet Protocol number 5 to encapsulate its datagram. Though it was never brought into public use, but it was already used. Here is a table of IP version and their use: Brief History After IPv4’s development in early 80s, the available IPv4 address pool begun to shrink rapidly as the demand of addresses exponentially increased with Internet. Taking pre-cognizance of situation that might arise IETF, in 1994, initiated the development of an addressing protocol to replace IPv4. The progress of IPv6 can be tracked by means of RFC published: 1998 – RFC 2460 – Basic Protocol 2003 – RFC 2553 – Basic Socket API 2003 – RFC 3315 – DHCPv6 2004 – RFC 3775 – Mobile IPv6 2004 – RFC 3697 – Flow Label Specification 2006 – RFC 4291 – Address architecture (revision) 2006 – RFC 4294 – Node requirement June 06, 2012 some of Internet giants chose to put their Servers on IPv6. Presently they are using Dual Stack mechanism to implement IPv6 parallel with IPv4. Features The successor of IPv4 is not designed to be backward compatible. Trying to keep the basic functionalities of IP addressing, IPv6 is redesigned entirely. It offers the following features: Larger Address Space: In contrast to IPv4, IPv6 uses 4 times more bits to address a device on the Internet. This much of extra bits can provide approximately 3.4×1038 different combinations of addresses. This address can accumulate the aggressive requirement of address allotment for almost everything in this world. According to an estimate, 1564 addresses can be allocated to every square meter of this earth. Simplified Header: IPv6’s header has been simplified by moving all unnecessary information and options (which are present in IPv4 header) to the end of the IPv6 header. IPv6 header is only twice as bigger than IPv4 providing the fact the IPv6 address is four times longer. End-to-end Connectivity: Every system now has unique IP address and can traverse through the internet without using NAT or other translating components. After IPv6 is fully implemented, every host can directly reach other host on the Internet, with some limitations involved like Firewall, Organization’s policies, etc. Auto-configuration: IPv6 supports both stateful and stateless auto configuration mode of its host devices. This way absence of a DHCP server does not put halt on inter segment communication. Faster Forwarding/Routing: Simplified header puts all unnecessary information at the end of the header. All information in first part of the header are adequate for a Router to take routing decision thus making routing decision as quickly as looking at the mandatory header. IPSec: Initially it was decided for IPv6 to must have IPSec security, making it more secure than IPv4. This feature has now been made optional. No Broadcast: Though Ethernet/Token Ring are considered as broadcast network because they support Broadcasting, IPv6 does not have any Broadcast support anymore left with it. It uses multicast to communicate with multiple hosts. Anycast Support: This is another characteristic of IPv6. IPv6 has introduced Anycast mode of packet routing. In this mode, multiple interfaces over the Internet are assigned same Anycast IP address. Routers, while routing, sends the packet to the nearest destination. Mobility: IPv6 was designed keeping mobility feature in mind. This feature enables hosts (such as mobile phone) to roam around in different geographical area and remain connected with same IP address. IPv6 mobility feature takes advantage of auto IP configuration and Extension headers. Enhanced Priority support: Where IPv4 used 6 bits DSCP (Differential Service Code Point) and 2 bits

IPv6 – Useful Resources ”; Previous Next The following resources contain additional information on IPv6. Please use them to get more in-depth knowledge on this topic. Useful Video Courses Computer Networks Online Course 107 Lectures 8 hours Tutorialspoint More Detail CompTIA A+ Certification Training: Core 1 (220-1001) Best Seller 133 Lectures 17.5 hours Total Seminars More Detail IT Security Gumbo: CCNA Training 19 Lectures 1.5 hours Corey Charles More Detail Network+ (N10-007): The Complete Course 46 Lectures 14 hours Lazaro Diaz More Detail Cisco CCNA: The A, B, C”s of IPv6 16 Lectures 3.5 hours Lazaro Diaz More Detail IPv6: Internet Protocol version 6 30 Lectures 4 hours TELCOMA Global More Detail Print Page Previous Next Advertisements ”;

Transition From IPv4 to IPv6 ”; Previous Next Complete transition from IPv4 to IPv6 might not be possible because IPv6 is not backward compatible. This results in a situation where either a site is on IPv6 or it is not. It is unlike implementation of other new technologies where the newer one is backward compatible so the older system can still work with the newer version without any additional changes. To overcome this short-coming, we have a few technologies that can be used to ensure slow and smooth transition from IPv4 to IPv6. Dual Stack Routers A router can be installed with both IPv4 and IPv6 addresses configured on its interfaces pointing to the network of relevant IP scheme. [Image: Dual Stack Router]In the above diagram, a server having IPv4 as well as IPv6 address configured for it can now speak with all the hosts on both the IPv4 as well as the IPv6 networks with the help of a Dual Stack Router. The Dual Stack Router, can communicate with both the networks. It provides a medium for the hosts to access a server without changing their respective IP versions. Tunneling In a scenario where different IP versions exist on intermediate path or transit networks, tunneling provides a better solution where user’s data can pass through a non-supported IP version. [Image: Tunneling]The above diagram depicts how two remote IPv4 networks can communicate via a Tunnel, where the transit network was on IPv6. Vice versa is also possible where the transit network is on IPv6 and the remote sites that intend to communicate are on IPv4. NAT Protocol Translation This is another important method of transition to IPv6 by means of a NAT-PT (Network Address Translation – Protocol Translation) enabled device. With the help of a NAT-PT device, actual can take place happens between IPv4 and IPv6 packets and vice versa. See the diagram below: [Image: NAT – Protocol Translation]A host with IPv4 address sends a request to an IPv6 enabled server on Internet that does not understand IPv4 address. In this scenario, the NAT-PT device can help them communicate. When the IPv4 host sends a request packet to the IPv6 server, the NAT-PT device/router strips down the IPv4 packet, removes IPv4 header, and adds IPv6 header and passes it through the Internet. When a response from the IPv6 server comes for the IPv4 host, the router does vice versa. Print Page Previous Next Advertisements ”;

IPv6 – Features ”; Previous Next The successor of IPv4 is not designed to be backward compatible. Trying to keep the basic functionalities of IP addressing, IPv6 is redesigned entirely. It offers the following features: Larger Address Space In contrast to IPv4, IPv6 uses 4 times more bits to address a device on the Internet. This much of extra bits can provide approximately 3.4×1038 different combinations of addresses. This address can accumulate the aggressive requirement of address allotment for almost everything in this world. According to an estimate, 1564 addresses can be allocated to every square meter of this earth. Simplified Header IPv6’s header has been simplified by moving all unnecessary information and options (which are present in IPv4 header) to the end of the IPv6 header. IPv6 header is only twice as bigger than IPv4 provided the fact that IPv6 address is four times longer. End-to-end Connectivity Every system now has unique IP address and can traverse through the Internet without using NAT or other translating components. After IPv6 is fully implemented, every host can directly reach other hosts on the Internet, with some limitations involved like Firewall, organization policies, etc. Auto-configuration IPv6 supports both stateful and stateless auto configuration mode of its host devices. This way, absence of a DHCP server does not put a halt on inter segment communication. Faster Forwarding/Routing Simplified header puts all unnecessary information at the end of the header. The information contained in the first part of the header is adequate for a Router to take routing decisions, thus making routing decision as quickly as looking at the mandatory header. IPSec Initially it was decided that IPv6 must have IPSec security, making it more secure than IPv4. This feature has now been made optional. No Broadcast Though Ethernet/Token Ring are considered as broadcast network because they support Broadcasting, IPv6 does not have any broadcast support any more. It uses multicast to communicate with multiple hosts. Anycast Support This is another characteristic of IPv6. IPv6 has introduced Anycast mode of packet routing. In this mode, multiple interfaces over the Internet are assigned same Anycast IP address. Routers, while routing, send the packet to the nearest destination. Mobility IPv6 was designed keeping mobility in mind. This feature enables hosts (such as mobile phone) to roam around in different geographical area and remain connected with the same IP address. The mobility feature of IPv6 takes advantage of auto IP configuration and Extension headers. Enhanced Priority Support IPv4 used 6 bits DSCP (Differential Service Code Point) and 2 bits ECN (Explicit Congestion Notification) to provide Quality of Service but it could only be used if the end-to-end devices support it, that is, the source and destination device and underlying network must support it. In IPv6, Traffic class and Flow label are used to tell the underlying routers how to efficiently process the packet and route it. Smooth Transition Large IP address scheme in IPv6 enables to allocate devices with globally unique IP addresses. This mechanism saves IP addresses and NAT is not required. So devices can send/receive data among each other, for example, VoIP and/or any streaming media can be used much efficiently. Other fact is, the header is less loaded, so routers can take forwarding decisions and forward them as quickly as they arrive. Extensibility One of the major advantages of IPv6 header is that it is extensible to add more information in the option part. IPv4 provides only 40-bytes for options, whereas options in IPv6 can be as much as the size of IPv6 packet itself. Print Page Previous Next Advertisements ”;