Appendix
31
© 2012 Patapsco Designs Ltd
10BT
An Ethernet standard that transmits at 10 Mbps
802.1p
An IEEE standard for providing quality of service (QoS) in 802-based networks
A- Law
The companding algorithm used for voice communications used in most of the world except North America
and Japan
AMI
A T1 Line Code standard. Alternate Mark Inversion - Basic bipolar encoding.
AN SI
The American National Standards Institute, who with the ITU-T standardized ISDN in the USA
Auto- N egotiation A system whereby two Ethernet devices automatically configure their duplex modes and link speeds
B8ZS
A T1 Line Code standard. Bipolar with 8 Zeros Substitution - Point-to-point T-carrier line coding.
B- channel
A single 64kbps channel, part of a PRI or BRI connection.
Barring
A profile which can be used to block a particular DDI, CLI, MSN or Subaddress from being routed
Bit Rate
The Tx and/or Rx rate of a link. Can be determined by Byte Count or Frames per Packet
BRI
Basic Rate Interface. A 2 x 64kbps channel (2b + d) ISDN interface
Broadcast
A packet sent to all devices on a network
Byte Count
The same as the Frames per Packet setting, but configurable with the granularity of bytes rather than frames,
and also configurable with asymmetrical Tx and Rx rates.
Channel
A single 64kbps Channel or Timeslot on a data connection
Checksum
A code used for checking the integrity of data. Where Patapsco devices are concerned, a Checksum is used
to check the integrity of the firmware file used by devices
CLI
Calling Line Identifier. The number of the calling party in a telephone call
CLIR
Calling Line Identifier Restricted. A function which must be supported by the ISDN carrier, which is used to
hide the CLI of a caller.
Clock
The pulse used to keep data equipment synchronized. This comes from one ‘Master’ source, apart from in
PDH environments
Clock Recov ery
A method by which the clock pulse is sent across an asynchronous IP link and used to synchronize a remote
device with the local one.
Codepoint
A hexadecimal value in the range 00-63 (or 0-3F in hexadecimal) used for Diffserv tagging on some
Patapsco products
Conv ersion
A type of Call Routing Profile used to add, edit or remove DDI, CLI or Subaddress numbers. Can also be
used to activate the CLIR function.
CRC4
CRC-4 (Cyclic Redundancy Checking 4) is a form of cyclic redundancy checking which is used to check for
for errors in transmitted data.
D- channel
Used in ISDN communications to carry signaling information, consisting of 16kbps on a BRI interface and
64kbps on a PRI interface.
DCO
Derived Clock Offset. The difference (in parts-per-billion) between a source clock signal and a clock signal
passed across a Packet Switched Network and recovered by a slave unit.
DDI
Direct Dial-In. One of a group of numbers which are usually assigned to users on a PRI circuit. The single
network connection can have a large group of numbers associated with it, usually with one DDI for each
user. Callers can dial the DDI of the user they want to call instead of the ‘main’ number of the line.
Debug
Patapsco devices can be set to Debug mode, which outputs detailed information about the status of the
device and any connections active on the blue Terminal window. This information can then be saved, which
