Q. Diffrence between Network vs Internet Layers?

- Similar to all the other OSI Layers the network layer provides both connectionless and connection-oriented services. From the TCP/IP architecture the internet layer is exclusively connectionless.

- X.25 Packet Level Protocol OSI's Connection-oriented Network Protocol

• The CCITT standard for X.25 describes the DTE/DCE interface standard to provide access to a packet-switched network. It is the network level interface that specifies a virtual circuit (VC) service. A source host should establish a connection (a VC) with the destination host before data transfer can take place. The network attempts to bring packets flowing over a VC in sequence.

- Connectionless Network Service

• Both OSI in addition to TCP/IP support a connectionless network service OSI as an alternative to network connections as well as TCP/IP as the only way in use

- Internetworking Protocols

• OSI's CLNP (ISO/IEC 8473: 1993) is functionally the same to the Internet's IP (RPC 791). Both CLNP as well as IP are best-effort-delivery network protocols. Bit niggling apart they are virtually identical. The main difference between the two is that CLNP accommodates variable-length addresses whereas IP supports fixed 32-bit address.