In most cases, the address of a system is the IP address (for example, 192.168.5.45). If you talk about the address of a server, client or peer, this also comprises the port number (for example, 192.168.5.45:5548).
See “unicast”.
Berkeley Software Distribution
A client is a part of a communications application. The initially active part establishes a connection (TCP) or sends data to the server.
Domain Name System
A physical and data link layer technology for LANs, also known as IEE 802.3.
Ethernet is the most widely spread technology for local networks. Each PacDrive controller has an Ethernet port. The Ethernet standard defines layer 1 and 2 of the communication. Above the Ethernet, there are many different network protocols but only IP is used.
The Internet Group Management Protocol (IGMP) is a communications protocol used by hosts and adjacent routers on IPv4 networks to establish multicast group memberships.
IP (Internet Protocol) is the protocol below TCP and UDP, which transports the data across the network.
IP is part of the TCP/IP protocol family that tracks the Internet addresses of devices, routes outgoing messages, and recognizes incoming messages.
The IP address of IPv4 (Internet Protocol version 4) is a value of 4 bytes which identifies the devices connected to an IP network.
See “unicast”.
On network level, the term packet is used for the data packets which this level transmits. In the case of UDP, these terms are used synonymously.
Term for the other system participating in the communication. This term is used if it is unimportant whether the other system is a server or a client.
A port number, frequently also designated as port, is a number from 1 to 65535. In combination with an IP address, it designates a communication end point. A socket is always connected with a port number. As sockets are used by the communication function blocks of TCP/UDP communication, and these again by a program, a port number identifies a program, a server, or a client running on a controller.
If you communicate with the <IP of a controller>:<Port number>, then you communicate with a program that has connected itself to this port number. (The program has configured its communication function block such that it connects to this port number.)
A server is a part of a communications application. At first, the server is passive. It waits until clients initialize communication. A server runs on a defined port number and the clients know its address.
A socket is a resource which is used by TCP/UDP communication internally in order to access the communications functions in the firmware.
TCP (Transmission Control Protocol) is a transmission protocol used in IP networks.
TTL (Time to live) or hop limit is a mechanism that limits the lifespan or lifetime of data in a computer or network.
Under the Internet Protocol (IP), TTL can be implemented as a counter or timestamp attached to or embedded in the data. Once the defined event count or timespan has elapsed, data is discarded.
Under DNS, TTL prevents a data packet from circulating indefinitely.
UDP (User Datagram Protocol) is a transmission protocol used in IP networks.
unicast / broadcast /multicast
Unicast communication targets one system as destination. For unicast communication, either TCP or UDP can be used.
Broadcast communication targets all systems in the same subnet. As with multicast, only UDP can be used.
Multicast targets some systems that have to join a specified multicast-group before being delivered packets targeted at that group.
