User manual

Publication date: Feb., 2013
Revision A3
275
programs at each end have been exchanged. TCP is responsible for ensuring that a message
is divided into the packets that IP manages and for reassembling the packets back into the
complete message at the other end.
Common network applications that use TCP include the World Wide Web (WWW), e-mail,
and File Transfer Protocol (FTP).
TELNET
TELNET is an acronym for TELetype NETwork. It is a terminal emulation protocol that uses
the Transmission Control Protocol (TCP) and provides a virtual connection between TELNET
server and TELNET client.
TFTP
TFTP is an acronym for Trivial File Transfer Protocol. It is transfer protocol that uses the User
Datagram Protocol (UDP) and provides file writing and reading, but it does not provide
directory service and security features.
U
UDP
UDP is an acronym for User Datagram Protocol. It is a communications protocol that uses the
Internet Protocol (IP) to exchange the messages between computers.
UDP is an alternative to the Transmission Control Protocol (TCP) that uses the Internet
Protocol (IP). Unlike TCP, UDP does not provide the service of dividing a message into packet
datagrams, and UDP doesn't provide reassembling and sequencing of the packets. This
means that the application program that uses UDP must be able to make sure that the entire
message has arrived and is in the right order. Network applications that want to save
processing time because they have very small data units to exchange may prefer UDP to TCP.
UDP provides two services not provided by the IP layer. It provides port numbers to help
distinguish different user requests and, optionally, a checksum capability to verify that the data
arrived intact.
Common network applications that use UDP include the Domain Name System (DNS),
streaming media applications such as IPTV, Voice over IP (VoIP), and Trivial File Transfer
Protocol (TFTP).
User Priority
User Priority is a 3-bit field storing the priority level for the 802.1Q frame. It is also known as
PCP.
V
VLAN
Virtual LAN. A method to restrict communication between switch ports. VLANs can be used
for the following applications:
VLAN unaware switching: This is the default configuration. All ports are VLAN unaware with
Port VLAN ID 1 and members of VLAN 1. This means that MAC addresses are learned in
VLAN 1, and the switch does not remove or insert VLAN tags.