This layer, also known as the network layer, accepts and delivers packets for the network. This layer includes the powerful Internet Protocol (IP), the Address Resolution Protocol (ARP), and the Internet Control Message Protocol (ICMP).
IP addressing – The IP addressing conventions are part of the IP protocol. Chapter 3, Planning Your TCP/IP Network (Task) describes IPv4 addressing in detail and Chapter 14, IPv6 (Overview) describes IPv6 addressing in detail.
Packet formatting – IP assembles packets into units that are known as IP datagrams. Datagrams are fully described in Internet Layer.
Fragmentation – If a packet is too large for transmission over the network media, IP on the sending host breaks the packet into smaller fragments. IP on the receiving host then reconstructs the fragments into the original packet.
Previous releases of the Solaris operating environment implement version 4 of the Internet Protocol, which is abbreviated as IPv4. However, because of the rapid growth of the Internet, a new Internet Protocol was created. The new protocol increases address space. This new version, known as version 6, is abbreviated as IPv6. The Solaris operating environment supports both versions, which are described in this book. To avoid confusion when addressing the Internet Protocol, one of the following conventions is used:
When the term IP is used in a description, the description applies to both IPv4 and IPv6.
When the term IPv4 is used in a description, the description applies only to IPv4.
When the term IPv6 is used in a description, the description applies only to IPv6.
The Address Resolution Protocol (ARP) conceptually exists between the data-link and Internet layers. ARP assists IP in directing datagrams to the appropriate receiving host by mapping Ethernet addresses (48 bits long) to known IP addresses (32 bits long).
Connectivity failure – A destination host that cannot be reached)
The ping Command contains more information on the operating system commands that use ICMP for error detection.