User`s guide

D-6
Glossary
DAS (dual attachment station)
An FDDI station connected to both the primary and secondary
rings.
data link layer
Layer 2 in the OSI model. Defines frame construction, addressing,
error detection and other services to higher layers.
datagram
Abbreviated and connectionless single-packet message sent from
one station to another.
data rate (or speed)
The maximum number of bits of information that can be
transmitted per second.
DDP (Datagram Delivery Protocol)
DDP is the network layer protocol for AppleTalk used for end-to-
end addressing. The 13 byte header contains checksum, length,
source and destination address, and packet type. The data portion
of the packet is 0-586 bytes long.
destination address filtering
A process which discards (filters) local traffic and forwards only
data intended for nodes on the extended LAN (non-local traffic).
downstream
Refers to the relative position of a station in a ring or network to
another station in the same ring or network. A station is