Internet Protocol (IP)
This is the layer 3 (network)
component of the TCP/IP protocol.
IP is a connectionless datagram
service.
NOTE: Routing is performed at this layer!
IP datagrams are not acknowledged
and they can have unique, multicast or broadcast address destinations.
As datagrams are connectionless,
they do not have a fixed route. This powerful concept allows datagrams to be re-routed
through other paths thus catering for network failures.
The IP datagram encapsulates the
higher layer protocols and is itself encapsulated in the datalink frame.
IP sometimes has to split
(fragment) datagrams that are larger than the maximum length the medium can handle. This
maximum length is referred to as Maximum Transmission Unit (MTU).
Re-assembly of fragmented datagrams
are performed only at the destination even if the segment in middle can handle larger
sizes.
An example:
Type |
MTU |
IEEE 802.3 | 1492 bytes |
Ethernet | 1500 bytes |
This inherent size limitation is
invisible to the layers above IP!
The mechanism for IP addressing is
described in detail in another subsection.
Maintained by Mohan Atreya , Last update April 8, 1999 First created on November 10, 1998 |