EE5412 Telecommunication Networks

EE5412 [TCPIP/IPV6.doc]

[Computer Network and Internets; Dougles E Comer] [Ch14,15,18,19]

The future IP – IPV6

Motivation for change –

1. Address space limitation – larger addresses necessary to accommodate continued growth of Internet.

2. New applications –

Real time transmission for Audio & video
To keep such information flowing through the Internet without disruption, IP must avoid changing routes frequently.

Although the current IP datagram header includes a field that can be used to request a type of service, the protocol did not define a type of service that can be used for real time delivery of data.

More complex addressing and routing capabilities

Communication among a group of colleagues analogous to a telephone conference call .
To make collaboration effective, an internet needs a mechanism that allow groups to be created or changed, and provides a way to send a copy of a packet to each participant in a given group.

Groups to handle load sharing
That is, several identical copies of a service exist, and a packet sent to the group is routed to the copy of the service that is closest to the sender.

Characterization of Features in IPv6
1. Connectionless – each datagram contains a destination address and is routed independently.
2. The header contains a max number of hops before being discarded.


New features in IPV6 –
Address Size – 128 bits instead of 32 bits
Header Format – completely new format
Extension Header – A datagram consists of the base header followed by zero or more extension headers followed by data.

Support for audio and video – allows a sender and receiver to establish a high quality path through the network and to associate datagrams with that path. Mechanism is intended for use with audio and video applications that require high performance guarantees. The mechanism can also be used to associate datagrams with low-cost paths.

Extensible Protocol – does not specify all possible protocol features. The header extension scheme allow new features can be added to new design as needed.

IPV6 Datagram format

Base header plus data with optional extension header
Options in payload area of base header




IPV6 Base Header format - fewer field than IPV4


Version

Flow Label – divided into two parts – one used to specify a traffic class and the other used to define a specific path. Routers use the value to route the datagram along the prearranged path. A label is used and label is assigned by system on path setup.

Payload length – size of data carried

Next Header – specify the type of information that follows the current header.

Hop Limit – discard if hop limit counts down to zero

Source Address – 16 Octets

Destination Address – 16 Octets

Multiple headers – use Next Header field to determine the contents of multiple headers. Allow new or experimental header to add on without affecting the operation of the existing headers as long as the new header appears after the existing headers.

IPV6 Addressing - three basic types
Unicast – to a single computer ;
Multicast – one copy to each of the member;
Cluster – computers share a common address - datagram send to one of the computer [the nearest one]
Allow replication of services.

IPV6 Colon Hexadecimal Notation - written in hexadecimal with a colon separating groups.