HP-UX VLAN Administrator's Guide, February 2007

priority A field in the VLAN tag portion of the frame header. Some switch vendors have implemented
a priority mechanism that acts on this 3-bit priority encoded in the VLAN tag to provide
rudimentary Class of Service (CoS).
See also 802.1p.
protocol A specification for communicating between devices, including the format and processing of
messages.
QoS Quality of Service. The ability to provide guarantees for data transfer - for example, latency,
throughput, and discard priority.
route A path through a network from one node to another.
router 1. A device that forwards or routes IP packets based on the destination IP address. A router
connects IP networks or subnets and is an OSI Layer 3 device. 2. A node (computer system or
other device) in an IP network that forwards IP packets not addressed to itself.
SMH HP System Management Homepage (HP SMH). The system administration tool for managing
HP-UX 11i Version 3, it provides web-based system management functionality, at-a-glance
monitoring of system component health, and consolidated log viewing. HP SMH also provides
terminal user interfaces (TUIs). HP SMH replaces System Administration Manager (SAM).
switch A network interconnection device that enables multiple connected senders and receivers to
communicate simultaneously, in contrast to a hub (repeater) in which only one device can send
at a time. Some switches have fixed port speeds (10-Mb/s or 100-Mb/s), while others enable
port speeds to be configured or autonegotiated.
TCP Transmission Control Protocol. The Internet transport-layer protocol that provides a reliable,
full-duplex, connection-oriented service for applications. TCP uses IP to transmit information
through the network.
TCP/IP The two fundamental protocols of the Internet Protocol Suite, and an acronym that is frequently
used to refer to the Internet Protocol Suite. TCP provides for the reliable transfer of data, while
IP transmits the data through the network in the form of datagrams.
See also IP, TCP.
topology The physical and logical geometry governing placement of nodes in a computer network. Also,
the layout of the transmission medium for a network.
ToS Type of service. ToS Indicates the desired service expected by an IP packet for delivery through
routers across the IP internetwork. In IPv4, ToS is 8 bits of the Type of Service field, which
includes bits for precedence, delay, throughput, and reliability characteristics. In IPv6 ToS is
part of the Traffic Class field.
transmission
control protocol
See TCP.
virtual PPA See VPPA.
VLAN Virtual LAN. A VLAN is a logical (virtual) network segment that can span multiple physical
network segments. VLAN technology provides a means for separating logical network
connectivity from physical connectivity. Specifically, VLAN technology can be used to divide
a physical LAN into multiple logical LAN segments or broadcast domains. VLAN interfaces
that share the same VLAN ID can communicate to each other as if they were on the same
physical network. VLANs help reduce broadcast traffic, increase network performance and
security, and improve manageability.
VLAN ID A VLAN ID uniquely identifies the VLAN to which a frame belongs.
VLAN tag A 4-byte extension to the MAC header, consisting of a 2 byte VLAN protocol ID (0x8100) and
2-bytes of tag control information. VLAN tags enable traffic from more than one VLAN to use
the same port.
VLAN-aware Devices such as switches and end stations that can recognize VLAN tags but do not actually
interpret them.
See also VLAN-tag aware.
VLAN-tag aware Devices such as switches, routers, and end stations that can interpret VLAN tags. See also
VLAN-aware.
58 Glossary