Glossary-5
Glossary
Network Time Protocol (NTP)
NTP provides the mechanisms to synchronize time across the network. The time
servers operate in a hierarchical-master-slave configuration in order to synchronize
local clocks within the subnet and to national time standards via wire or radio.
Open Shortest Path First (OSPF)
OSPF is a link-state routing protocol that functions better over a larger network such
as the Internet, as opposed to distance-vector routing protocols such as RIP. It
includes features such as unlimited hop count, authentication of routing updates,
and Variable Length Subnet Masks (VLSM).
Out-of-Band Management
Management of the network from a station not attached to the network.
Port Authentication
See IEEE 802.1x.
Port Mirroring
A method whereby data on a target port is mirrored to a monitor port for
troubleshooting with a logic analyzer or RMON probe. This allows data on the target
port to be studied unobstructively.
Port Trunk
Defines a network link aggregation and trunking method which specifies how to
create a single high-speed logical link that combines several lower-speed physical
links.
Private VLANs
Private VLANs provide port-based security and isolation between ports within the
assigned VLAN. Data traffic on downlink ports can only be forwarded to, and from,
uplink ports.
Protocol-Independent Multicasting (PIM)
This multicast routing protocol floods multicast traffic downstream, and calculates
the shortest-path back to the multicast source network via reverse path forwarding.
PIM uses the router’s IP routing table rather than maintaining a separate multicast
routing table as with DVMRP. PIM - Sparse Mode is designed for networks where
the probability of a multicast client is low, such as on a Wide Area Network. PIM -
Dense Mode is designed for networks where the probability of a multicast client is
high and frequent flooding of multicast traffic can be justified.
Remote Authentication Dial-in User Service (RADIUS)
RADIUS is a logon authentication protocol that uses software running on a central
server to control access to RADIUS-compliant devices on the network.
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