Digitus DN-80233, User Manual

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ASBR.
See “Autonomous System Boundary Router” on page 294.
ATM Subscriber Access Multiplexer.
A telephone central office multiplexer that supports SDL ports
over a wide range of network interfaces. An ASAM sends and receives subscriber data (often Internet
services) over existing copper telephone lines, concentrating all traffic onto a single high-speed trunk for
transport to the Internet or the enterprise intranet. This device is similar to a DSLAM (different
manufacturers use different terms for similar devices).
Autonomous System Boundary Router.
ABR located between an OSPF autonomous system and a
non-OSPF network. ASBRs run both OSPF and another routing protocol, such as RIP. ASBRs must
reside in a non-stub OSPF area. See also ABR, non-stub area, and OSPF.
AVL tree.
Binary tree having the property that for any node in the tree, the difference in height between
the left and right sub-trees of that node is no more than 1.
B
BPDU.
See “Bridge Protocol Data Unit” on page 295.
BGP.
See “Border Gateway Protocol” on page 295.
BootP.
See “Bootstrap Protocol.” on page 295.
Bootstrap Protocol.
An Internet protocol that enables a diskless workstation to discover its own IP
address, the IP address of a BootP server on the network, and a file to be loaded into memory to boot the
machine. This enables the workstation to boot without requiring a hard or floppy disk drive.
Border Gateway Protocol.
BGP is a protocol for exchanging routing information between gateway host
(each with its own router) in a network of autonomous systems. BGP is often the protocol used between
gateway hosts on the Internet. The routing table contains a list of known routers, the addresses they can
reach, and a cost metric associated with the path to each router so that the best available route is chosen.
Hosts using BGP communicate using the Transmission Control Protocol (TCP) and send updated router
table information only when one host has detected a change. Only the affected part of the routing table is
sent. BGP-4, the latest version, lets administrators configure cost metrics based on policy statements.
(BGP-4 is sometimes called BGP4, without the hyphen.) BGP communicates with autonomous (local)
networks using Internal BGP (IBGP) since it doesn't work well with IGP. The routers inside the
autonomous network thus maintain two routing tables: one for the interior gateway protocol and one for
IBGP. BGP-4 makes it easy to use Classless Inter-Domain Routing (Classless Inter-Domain Routing),
which is a way to have more addresses within the network than with the current IP address assignment
scheme.
Bridge Protocol Data Unit.
BPDU is the IEEE 802.1D MAC Bridge Management protocol that is the
standard implementation of STP (Spanning Tree Protocol). It uses the STP algorithm to insure that
physical loops in the network topology do not result in logical looping of network traffic. Using one bridge
configured as root for reference, the BPDU switches one of two bridges forming a network loop into
standby mode, so that only one side of a potential loop passes traffic. By examing frequent 802.1d
configuration updates, a bridge in the standby mode can switch automatically into the forward mode if the
other bridge forming the loop fails.
cards.h.
A file that instructs the base code driver how to construct the driver.
card_db.
A database that contains everything from port maps to module information.
Checksum.
A simple error-detection scheme in which each transmitted message is identified with a
numerical value based on the number of set bits in the message. The receiving station then applies a
formula to the message and checks to make sure the accompanying numerical value is the same. If not,
the receiver can assume that the message has been corrupted.
CLI.
See “Command Line Interface” on page 295.