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Internet Protocol v6

Internet Protocol v6. Part 6 NVCC Professional Development TCP/IP. Issues with IPv4. Address Space

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Internet Protocol v6

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  1. Internet Protocol v6 Part 6 NVCC Professional Development TCP/IP

  2. Issues with IPv4 • Address Space • The address space is too small to accommodate Internet growth. The internet is expected to run out of address space between 2005 and 2011 due to the growth in mobile, wireless personal computers due to increased commerce, and the demand for real-time audio/video due to the impending convergence of the computer, communication and entertainment industries. • Routing • There has been an explosion in the size of routing tables that is putting severe strains on many systems. • Security • Commerce has moved to Internet imposing its unique requirements, and attacks are on the increase. • Congestion • Organization Tunneling is leading to network congestion control problems. • In 1990 the IETF began to explore new network options that would solve these problems. • In 1995 the IPng Area of the IETF published it recommendation for a new protocol - IPv6.

  3. Enhanced IPv6 Features • Autoconfiguration – allows a host to find the info it needs to set up its own IP networking parameters by querying other nodes. • Stateless – calculate tentative address based on known parameters like link local prefix. • Stateful (DHCPv6) – rely on dedicated servers to hold databases about hosts and their IP and configurations. • Security • Suite of security protocols – IPSec is required • Support encryption, authentication • Quality of Service • Network can provide differentiated service to specific type of traffic. Option headers are used to implement QoS schemes

  4. Enhanced IPv6 Features • Mobile Users • Mobile IPv6, allows a mobile node to move from one link to another without changing the mobile node's IP address. • A mobile node is always addressable by its 'home address', an IP address assigned to the mobile node within its home subnet prefix on its home link. Packets may be routed to the mobile node using this address regardless of the mobile node's current point of attachment to the Internet. • The mobile node may also continue to communicate with other nodes (stationary or mobile) after moving to a new link. The movement of a mobile node away from its home link is thus transparent to transport and higher-layer protocols and applications.

  5. About IPv6 and Addressing • IPv6 solves the address shortage by creating an address space that is more than 20 orders of magnitude larger than IPv4. Enough IP addresses for every grain of sand on the planet! • IPv6 addresses are 128 bits long (vs 32 bits) • Expressed using hexadecimal notation • Broken up by colons rather than dotted octets • Addresses may be abbreviated if contiguous 16 bit groups of zeroes exist, by inserting double colon in place of zeroes • IPv6 requires that every network interface have a unique interface identifier • Addresses have three parts: the network identifier, the subnet, and the interface identifier. • Interface identifiers follow EUI-64 format. That is the existing 48 bits from the MAC address include an additional 16 bit pattern FFFE which is inserted between the two halves of the MAC address. FEDC:BA45:1234:3245:0000:0000:1234:ABCD FEDC:BA45:1234:3245::1234:ABCD

  6. IPv6 Address Types • IPv4 had unicast, broadcast and multicast addresses. IPv6 has unicast, multicast and anycast. With IPv6 the broadcast addresses are not used anymore, because they are replaced with multicast addressing. • IPv6 Unicast – a single address identifying a single interface. There are four types of unicast addresses: • Global unicast addresses, which are conventional, publicly routable address, just like conventional IPv4 publicly routable addresses. • Link-local addresses are akin to the private, non-routable addresses in IPv4 (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16). They are not meant to be routed, but confined to a single network segment. Link-local addresses mean you can easily create a temporary LAN, such as for conferences or meetings, or set up a permanent small LAN easily. • Unique local addresses are also meant for private addressing, with the addition of being unique, so that joining two subnets does not cause address collisions. • Special addresses are loopback addresses, IPv4-address mapped spaces, and 6-to-4 addresses for crossing from an IPv4 network to an IPv6 network.

  7. IPv6 Address Types • IPv6 Multicast - similar IPv4 broadcast address. • A packet sent to a multicast address is delivered to every interface in a group. Only hosts who are members of the multicast group receive the multicast packets. IPv6 multicast is routable, and routers will not forward multicast packets unless there are members of the multicast groups to forward the packets to. • Anycast - An anycast address is a single address assigned to multiple nodes. • A packet sent to an anycast address is then delivered to the first available node. • IPv6 anycast addresses contain fields that identify them as anycast, so all you need to do is configure your network interfaces appropriately. • IPv6 Prefix Allocations • 0000::/8 Reserved by IETF • 2000::/3 Global Unicast • FC00::/7 Unique Local Unicast • FE80::/10 Link Local Unicast • FF00::/8 Multicast

  8. IPv6 Addresses • The address space is written in colon hexadecimal notation • eight groups • four hexadecimal digits per group. • Colons (:) separate each group 01101000.11100110 .... Binary 104.230 ........ Decimal 128 bits 8 groups/16 bits ea Hexadecimal 68E6:0064:0000:0000:0000:0000:006A:FFFF • Three optimization rules are for use by system administrators. • Leading zeros within a group can be omitted • Two or more groups of zeros (16 bits) can be replaced by a pair of colons. • The double colon notation is applied only once in any address. • The following are valid addresses: 68E6:64::6A:FFFF FEBC:68E6:0000:0000:0000:7654:3210 = FEBC:68E6::7654:3210 FEBC:68E6:7654:3210:0000:0000:0000 = FEBC:68E6:7654:3210:: 0000:0000:0000:FEBC:68E6:0000:0000:0000 = ::FEBC:68E6:0000:0000:0000

  9. Format Prefix Binary Prefix Space Allocation Address Space Fraction IPv6 ADDRESS SPACE RECOMMENDED ALLOCATION 0::/8 0000 0000 reserved 1/256 100::/8 0000 0001 unassigned 1/256 200::/7 0000 001 ISO network address 1/128 400::/7 0000 010 novell(IPX) network Addresses 1/128 600::/7 0000 011 unassigned 1/128 800::/5 0000 1 unassigned 1/32 1000::/4 0001 unassigned 1/16 2000::/3 001 unassigned 1/8 4000::/3 010 provider based unicast address 1/8 6000:/3 011 unassigned 1/8 8000::/3 100 geographic based unicast address 1/8 A000::/3 101 unassigned 1/8 C000::/3 110 unassigned 1/8 E000::/4 1110 unassigned 1/16 F000::/5 1111 0 unassigned 1/32 F800::/6 1111 10 unassigned 1/64 FC00::/7 1111 110 unassigned 1/128 FE00::/9 1111 1110 0 unassigned 1/512 FE80::/10 1111 1110 10 link local address 1/1024 FEC0::/10 1111 1110 11 site local address 1/1024 FF00::/8 1111 1111 multicast address 1/256

  10. IPv6 Address Management • The designers of IPv6 relied heavily on Hierarchy. • The Internet Assigned Number Authority(IANA) delegates blocks of IPv6 address space to Regional Registries. • Regional Registries, in turn, can pass blocks of address spaces to Internet Service Providers who, in turn, allocate address space to Subscribers who, in turn, can assign Areas, Subnets and hosts, etc. Provider-Based Address ISP based Unicast IP address Format Prefix Registry Identifier ISP Identifier Subscriber Type Subscriber Identifier Subnetwork Identifier Subsystem Address(MAC) North America = 11000 Europe = 01000 Asia/Pacific = 10100 Obtained from RIPE, Internic, APNIC Obtained from ISP Obtained from ISP 16 bits 16 bits 8 bits 32bits 3 bits 5 bits 0101100000000001 0000001000000011 0000010000000101 0000011000000111 0000100000001001 48 bits 5 A 0 1 0 20 3 0 40 50 6 0 7 0 8 0 9 • This is an example of how a Provider-Based Address can embed a hierarchy. • The first 80 bits are broken into six hierarchy levels • The remaining 48 bits can define a particular subsystem (e.g., the MAC address).

  11. IPv6 Special Addresses • Unspecified address: 0:0:0:0:0:0:0:0 • An all zeroes value is used when no true address is available. • It is normally serves as the source address until the host true address is known. • It may not be used as a destination address. • Loopback address: 0:0:0:0:0:0:0:1 • This address is used by the host to send a message to itself. • It is never transmitted onto the network.

  12. IPv6 Header CLASS VERS Flow Label 4 bits 4 bits 24 bits • IPv6 header designed to reduce processing time on routers. • Six fields were removed, • Three fields renamed or altered. • Two new fields added. • Header is always 40 bytes long • IPv6 no longer allows packet to be fragmented while en route. If packet is too large for the next hop, it is discarded. Fragmenting must be handled at the source before sending the packet. Hop Limit Next Header Payload Length 8bits 8bits 16 bits Source IP Address 128 bits Destination IP Address 128 bits

  13. IPv6 Header Fields CLASS VERS Flow Label 4 bits 4 bits 24 bits • VERS – which version of IP, in this case 6. • CLASS – Sets traffic prioritization. Bits indicate whether traffic is delay sensitive, sets the precedence level of the packet. • Flow Label –. A flow is a sequence of packets from the source to the destination that requires some kind of special handling, e.g. real time audio and video. The flow label is used to identify the stream of traffic that requires this special handling • Payload Length – amount of data following the IPv6 header • Next header – indicates the next protocol such as TCP, UDP, ICMP or an extension header • Hop Limit is the old TTL renamed. Hop Limit Next Header Payload Length 8bits 8bits 16 bits Source IP Address 128 bits Destination IP Address 128 bits

  14. PRITY VERS Flow Label Extension Headers 4 bits 4 bits 24 bits Hop Limit Next Header Payload Length 8bits 8bits 16 bits Source IP Address 128 bits • NEXT HEADER. This field tells which of the extension headers, if any, follow the base header. • This is a replacement for the protocol field in IPv4. • If this is the last IP header, the next header field tells which transport protocol (TCP, UDP, ICMP, etc) handler receives the packet. • Each extension header also contains a Next Header field so the headers can be chained together. Destination IP Address 128 bits Next Header field Extension Header Description Hop-by-Hop Options Header Miscellaneous information for routers 0 TCP Header Transmission Control Protocol data 6 UDP Header User Datagram Protocol data 17 Routing Header Full or partial route to follow 43 Fragment header Data fragment management 44 Encapsulating Security Payload Encrypted content information 50 Authentication Header Sender's identity validation 51 ICMPv6 Internet Control Message Protocol version 6 58 No Next Header Information that nothing follows(future) 59 Destination Options Header Additional information for destination 60

  15. IPv6 Header with TCP/IP PRITY VERS Flow Label • All IP packets begin with the basic IP Header. • This is an example of an IPv6 IP packet that is followed immediately by the TCP packet rather than any intervening extension headers. • The Next Header field contains the protocol type identifying TCP - 6. • The extension headers, when required, are sandwiched between the IPv6 header and the upper layer header. 4 bits 4 bits 24 bits Hop Limit Payload Length Nxt Hdr : 6 8bits 16 bits Source IP Address 128 bits Destination IP Address 128 bits Destination Port Source Port 16 bits 16 bits Sequence Number 32 bits Acknowledgement Number 32 bits Reserved Offset Receive Window Size P A F R U S 6 bits 4 bits 16 bits Urgent Pointer Checksum 16 bits 16 bits Options (if any) TCP Data (if any)

  16. IPv6 Chained Extension Headers • All IP packets begin with the basic IP Header. • IP Extension Headers are used to convey information to the destination or intermediate routers. • The headers are chained together through the Next Header Field. The headers have a recommended order which makes it easier for router processing. • The Destination Options should be the last extension header since it is information for the destination host or if intended for an intermediate router it should immediately precede the routing options header. • The final extension header indicates the upper level transport. PRITY VERS Flow Label 4 bits 4 bits 24 bits Hop Limit Payload Length Nxt Hdr : 0 8bits 16 bits Source IP Address 128 bits Destination IP Address 128 bits Nxt Hdr : 43 Hdr Length Hop-by-Hop Options Nxt Hdr : 44 Hdr Length Routing Information Nxt Hdr : 51 Reserved Fragment Offset M Fragment Options Nxt Hdr : 60 Hdr Length Authentication Data Nxt Hdr : 6 Hdr Length Destination Options TCP Header and Data

  17. Transitioning From IPv4 to IPv6 • Millions of systems use IPv4, therefore it will take many years to transition all nodes to IPv6. The slow cutover calls for transition strategies: • Dual Stack – hosts and routers run two versions of IP. • Tunneling through the IPv4 cloud – IPv6 packet is encapsulated in IPv4 packet, then envelope is stripped off upon reaching an IPv6 network. • On the fly creation of IPv6 address out of IPv4 addresses – embed IPv4 in predetermined IPv6 format. 2002:IPv4address:siteLocalAddress:InterfaceID

  18. Transitioning from IPv4 to IPv6 • To ease transition, the IETF has defined two types of IPv6 addresses that contain IPv4 address within them. • IPv4 compatible addresses • IPv4 mapped addresses • First 80 bits of both types are set to zeroes. Last 32 bits are for the existing 32 bit IP address. The 16 bits immediately proceeding the IPv4 address are set differently to distinguish between them.

  19. END OF LECTURE

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