CSE5803 Advanced Internet Protocols and Applications (13) Introduction Existing IP (v4) was developed in late 1970’s, when computer memory was about 32 Kbytes (2 15 ), to 512 Mbytes (2 29 ) or more today, processor speed, core network speed also increased by a factor of about 1000 times. Internet users have increased by many millions. The flexibility of IP and other measures such as VLSM/CIDR, DHCP, NAT, extended the life of IPv4 until today, but it is not going to accommodate the projected growth. Three main factors for the development of a new version of IP : –The need for more addresses –The need for guarantee of Quality of Services (QoS) –The need for secure communication (sender authentication)

CSE5803 Advanced Internet Protocols and Applications (13) Basic Features of IPv6 IPv6 (RFC1883, 2460) is also known as IP – The Next Generation (IPng) 128 bit address, will not be exhausted in the foreseeable future and improve addressing structure (RFC1884, 2373). Flexible and simplified header format. IPv6 uses a set of optional headers. Improved options. Enhanced traffic control options. Support for network resource allocation. The IPv4 TOS field is replaced with a class field which can support real-time services Capability for extensions IPv6 Datagram General form: Base Header Extension … Extension Header 1 Header n Data … Optional

CSE5803 Advanced Internet Protocols and Applications (13) 3 Base header (40 octets) format: |Version| Traffic Class | Flow Label | | Payload Length | Next Header | Hop Limit | | Source Address (128-bit, 16 Octets) | | Destination Address (128-bit) | Version: 4-bit field specifies the version (6). Traffic Class: 8-bit traffic class field. This is used by a host or router to distinguish and differentiate priorities of IPv6 packets. Similar to IPv4 DiffServ TOS field. Flow Label: 20-bit flow label. This is used by a source to label sequences of packets that may require special handling by routers, e.g. a real-time service. This and the field above provides the basis for IPv6 QoS.

CSE5803 Advanced Internet Protocols and Applications (13) 4 Payload Length: 16-bit field specifies the number of octets carried in the datagram excluding this header. Next Header: 8-bit field. Each of the base and extension headers contains such a field, which is used to identify the type of header immediately following this header. Similar to IPv4 Protocol field. Hop Limit: 8-bit field similar to IPv4 TTL field. Source/Destination Address are the addresses of sender and the intended recipient (may not be the ultimate recipient if a routing header exists) IPv6 Extension Headers IPv6 packets may carry zero or more extension headers, each is identified by the Next Header field. IPv6 extension headers work like v4 options. They serve the purposes of fragmentation, source routing and authentication. They are optional and can be selectively applied. New functions can also be developed. There is an order of the extension headers when more than one is used.

CSE5803 Advanced Internet Protocols and Applications (13) 5 The extension headers are not processed until the packet reaches the first intended recipient. The parsing of an IPv6 datagram depends on the next header field in the base and extension header (if any). Fragmentation (with an extension header) is restricted to source only, not an intermediate router like v4. A Path MTU discovery must be performed by the source to identify the minimum MTU along the route to destination. The fragmentation and reassembly in IPv6 is therefore end-to-end. The Fragment Extension Header is used for this purpose.

CSE5803 Advanced Internet Protocols and Applications (13) 6 End-to-end fragmentation is designed to reduce the load of routers but does not accommodate route changes. If route change happens and the MTU is smaller than that originally discovered by the source, the intermediate router must perform tunneling.

CSE5803 Advanced Internet Protocols and Applications (13) 7 IPv6 uses routing extension header for (loose) source routing. IPv6 has two more extension headers to accommodate other IPv4 options. These are Hop-by-Hop Options and Destination Options extension headers IPv6 Address The address space is so large that everyone on earth now can have an internet as large as the current internet. The address space is about 3.4x10 38, can not be exhausted with current and foreseeable technology. (It takes 20 years to assign at the rate of 1 million per us) Colon Hexadecimal Notation for human consumption. Dotted Decimal will be too long, e.g is represented as: 68E6:8C64:FFFF:FFFF:0:1180:96A:FFFF Colon hex notation allows zeros to be compressed with a pair of colons, eg

CSE5803 Advanced Internet Protocols and Applications (13) 8 FF05:0:0:0:0:0:0:B3 can be written as FF05::B3 IPv4 addresses can be mapped to v6. For example: in IPv6 will be 0:0:0:0:0:0: , or :: Note the mixture of v4 and v6 expressions. Three IPv6 address types –Unicast: for a single connection on a host or router –Anycast/Cluster: A set of host connections share the same address, datagram is delivered to the closest member. –Multicast: A set (group) of hosts at multiple locations. Each requires a copy of the datagram. IPv6 does not use the term broadcast, it treats broadcast as a special case of multicast. It is easy to emulate broadcast with multicast. Allows multiple, simultaneous addresses per network connection, and also multiple prefix per network. Proposed address allocation (over 72% has been reserved for future use):

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CSE5803 Advanced Internet Protocols and Applications (13) 11 In RFC2373, IPv6 address format has been updated. A 64-bit MAC address has been included in the unicast IPv6 address. Geographic-based allocation was discontiued. Addresses available for local use (private addresses) are divided into link- and site-local addresses. The former for a single physical network while the latter for an organisational intranet. The term provider-based unicast address has been changed to aggregatable global unicast address, illustrated as follows (P Loshin):

CSE5803 Advanced Internet Protocols and Applications (13) 12 FP: Three-bit field to identify where it belongs in the IPv6 address space. TLA ID: The top-level aggregation identifier contains the highest-level routing information of the address (13-bit). RES: Reserved for future use (8-bit). NLA ID: The next-level aggregation identifier (24-bit). This can be used by large organisations or ISPs to plan their address hierarchy. SLA ID: The site-level aggregation identifier (16-bit). This is given to organisations to plan their internal network (subnet) structure. Interface ID: This field (64-bit) contains globally unique interface identifier (MAC address). This is based on the IEEE EUI-64 format. This field is big enough to allocate a different address for each interface.