Page 35 - M. Abrahim Thesis

Computer Network 2021

Figure 2-10 shown a TCP/IP Internet Layer Protocol

Several protocols operate at the TCP/IP Internet layer:

• IP—Provides connectionless, best-effort delivery routing of packets. It is not
concerned with the packets’ content. Instead, it looks for a way to move the
packets to their destination.

• Internet Control Message Protocol (ICMP)—Provides control and messaging
capabilities.

• Address Resolution Protocol (ARP)—Determines the data link layer addresses
(Media Access Control [MAC] addresses) for known IP addresses.

• Reverse Address Resolution Protocol (RARP)—Determines IP addresses when
data link layer addresses (MAC addresses) are known.
IP performs the following operations:

• Defining a packet and an addressing scheme

• Transferring data between the Internet layer and the network access layer

• Routing packets to remote hosts Finally, to clarify terminology, IP is sometimes
referred to as an unreliable protocol. This does not mean that IP does not
accurately deliver data across a network; it simply means that IP does not
perform error checking and correction. That function is handled by upper-layer
protocols from the transport or application layer.
Network Access Layer

The network access layer, shown in Figure 2-11, is also called the host-to-network layer.
It is the layer that is concerned with all the issues that an IP packet requires to make a physical

39