Novell LINUX ENTERPRISE SERVER 11 - ADMINISTRATION Administration Manual page 214

Table 17.1
Protocol
TCP
UDP
ICMP
IGMP
As shown in
change takes place in different layers. The actual network layer is the insecure data
transfer via IP (Internet protocol). On top of IP, TCP (transmission control protocol)
guarantees, to a certain extent, security of the data transfer. The IP layer is supported
by the underlying hardware-dependent protocol, such as ethernet.
200 Administration Guide
Several Protocols in the TCP/IP Protocol Family
Description
Transmission Control Protocol: a connection-oriented secure protocol.
The data to transmit is first sent by the application as a stream of data
and converted into the appropriate format by the operating system. The
data arrives at the respective application on the destination host in the
original data stream format it was initially sent. TCP determines whether
any data has been lost or jumbled during the transmission. TCP is im-
plemented wherever the data sequence matters.
User Datagram Protocol: a connectionless, insecure protocol. The data
to transmit is sent in the form of packets generated by the application.
The order in which the data arrives at the recipient is not guaranteed
and data loss is possible. UDP is suitable for record-oriented applica-
tions. It features a smaller latency period than TCP.
Internet Control Message Protocol: Essentially, this is not a protocol
for the end user, but a special control protocol that issues error reports
and can control the behavior of machines participating in TCP/IP data
transfer. In addition, it provides a special echo mode that can be viewed
using the program ping.
Internet Group Management Protocol: This protocol controls machine
behavior when implementing IP multicast.
Figure 17.1, "Simplified Layer Model for TCP/IP" (page 201), data ex-