Computer Networks

Network News Transfer Protocol (NNTP) is an application protocol used for transporting Usenet news articles (netnews) between news servers and for reading and posting articles by end user client applications.

Border Gateway Protocol is an exterior gateway routing protocol that enables groups of routers (called autonomous systems) to share routing information so that efficient, loop-free routes can be established. BGP is commonly used within and between Internet Service Providers (ISPs).

Synchronous Optical Networking (SONET) is a standardised protocol that transfers multiple digital bit streams over optical fiber using lasers or highly coherent light from light-emitting diodes (LEDs).

Gopher protocol is a TCP/IP application layer protocol designed for distributing, searching, and retrieving documents over the Internet. Gopher ecosystem is often regarded as the effective predecessor of the World Wide Web.

ATM networks are connection-oriented. Making a call requires first sending a message to set up a connection. After that, subsequent cells follow the same path to the destination. Cell delivery is not guaranteed, but their order is guaranteed. If cells 1 and 2 are sent in that order, then if both arrive, they will arrive in that order, never first 2 and then 1.

 The session layer provides the mechanism for opening, closing and managing a session between end-user application processes, i.e. a semi-permanent dialogue. Communication sessions consist of requests and responses that occur between applications.

Internet Control Message Protocol (ICMP) is used to test the internet. ICMP messages are typically used for diagnostic or control purposes or generated in response to errors in IP operations.

Network layer is responsible for packet forwarding, including routing through intermediate routers. Hence, routing is a concern of this layer.

The IEEE standard 802.2 defines the Logical Link Control (LLC).

DNS primarily uses User Datagram Protocol (UDP) on port number 53 to serve requests.

X.25 is a connection-oriented packet switched network.

Start and stop bits are added to synchronise the flow of data.

Bit Map Protocol is also a contention system. In Bit Map Protocol, the desire to transmit is broadcast before the actual transmission. Such protocols are called reservation protocols.

Time to live (TTL) or hop limit is a mechanism that limits the lifespan or lifetime of data in a computer or network. TTL may be implemented as a counter or timestamp attached to or embedded in the data. Once the prescribed event count or timespan has elapsed, data is discarded.

This network layer is primitive for Connection Less Service. It is used for enquiring into the performance of the network.