Digitus DN-80233, Руководство пользователя, Страница: 378 / 379

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Systems Application Programming Interface.
SYSAPI is a module within the System Support
software that provides system-wide routines for network and mbuf support and provides the interface into
the system registry.
T
TBI.
Ten Bit Interface.
Telnet.
A character-based UNIX application that enables users with a Telnet server account to log on to a
UNIX computer and utilize its resources.
TFTP.
See “Trivial File Transfer Protocol” on page 302.
Trivial File Transfer Protocol.
TFTP is a simple form of the File Transfer Protocol (FTP). TFTP uses
the User Datagram Protocol (UDP, a direct protocol used to communicate datagrams over a network with
little error recovery) and provides no security features. It is often used by servers to boot diskless
workstations, X-terminals, and routers.
Trunking.
The process of combing a set of trunks that are traffic-engineered as a unit for the
establishment of connections between switching systems in which all of the communications paths are
interchangeable.
U
UPM.
User Programmable Machine.
UPMA.
The first of two UPMs in Motorola's MPC855T processor.
UPMB.
The second of two UPMs in Motorola's MPC855T processor.
USP.
An abbreviation that represents Unit, Slot, Port.
Virtual Local Area Network.
Operating at the Data Link Layer (Layer 2 of the OSI model), the VLAN is a
means of parsing a single network into logical user groups or organizations, as if they physically resided
on a dedicated LAN segment of their own. In reality, this virtually defined community may have individual
members peppered across a large, extended LAN. The VLAN identifier is part of the 802.1Q tag, which is
added to an Ethernet frame by an 802.1Q-compliant switch or router. Devices recognizing 802.1Q-tagged
frames maintain appropriate tables to track VLANs. The first three bits of the 802.1Q tag are used by
802.1P to establish priority for the packet.
Virtual Router Redundancy Protocol.
VRRP specifies an election protocol that dynamically assigns
responsibility for a virtual router to one of the VRRP routers on a LAN. The VRRP router controlling the
IP address(es) associated with a virtual router is called the Master, and forwards packets sent to these
IP addresses. The election process provides dynamic fail-over in the forwarding responsibility should the
Master become unavailable. This allows any of the virtual router IP addresses on the LAN to be used as
the default first hop router by end-hosts. The advantage gained from using VRRP is a higher availability
default path without requiring configuration of dynamic routing or router discovery protocols on every
end-host.
VLAN.
See “Virtual Local Area Network” on page 302.
vMAN.
Virtual Metropolitan Area Network.
VRRP.
See “Virtual Router Redundancy Protocol” on page 302.
W
WAN.
See “Wide Area Network” on page 302.