MT92220 Zarlink Semiconductor, MT92220 Datasheet - Page 209

• Manufacturer Part Number: MT92220
• Description: 1023 Channel Voice Over IP/AAL2 Processor
• Manufacturer: Zarlink Semiconductor

Data Sheet
MT92220
Appendix D
Glossary of Terms
Standard Terms and Abbreviations
AAL0 (A TM A daptation L ayer 0): AAL0 is a straight packaging of 48 bytes of data within an ATM cell. AAL0 is often
used to carry signaling ATM cells, which are treated in this device as "raw cells".
AAL2 (A TM A daptation L ayer 2): AAL2 is used to transport Constant Bit Rate (CBR) and Variable Bit Rate (VBR)
data on ATM. AAL2 cells are made up of AAL2 mini-packets of different lengths containing different kinds of data.
AAL5 (A TM A daptation L ayer 5): AAL5 is a protocol used to carry higher-layer datagrams while enhancing the link
layer with services available through ATM. Defined in the ITU standard I.363.5, AAL5 is typically used to carry IP
datagrams over ATM, but can be used for other higher-layer protocols.
ADPCM (A daptive D ifferential P ulse C ode M odulation ): ADPCM is a compression standard that allows the
encoding of PCM data at rates of 40, 32, 24 and 16 kbps. Defined by the ITU standard G.726. ADPCM running at
32 kbps is often used as the definition of "toll" quality, or quality that is comparable or superior to that of the PSTN
today.
Application data: The "data" unit carried by the transport layer. This will typically be the UDP payload in a
voice-over-IP implementation, though it could be TCP payload or others for other applications.
ARP (A ddress R esolution P rotocol ): A protocol designed for Ethernet that allows the MAC address associated to a
network address (usually an IP address) to be known so the packet can be sent over Ethernet. Defined by IETF
RFC826 & STD37.
CID (C hannel ID entifier ): The CID is an 8-bit field that identifies an AAL2 Mini-Packet and determines which of the
255 AAL2 connections on this VC it belongs to. The value of 00h is illegal for the CID.
CLIP (CL assical IP Over ATM ): Encapsulation of IP packets over AAL5 using LLC and SNAP header to identify the
network protocol (in this case IP) being used.
CPU (C entral P rocessing U nit )
CRC (C yclic R edundancy C heck ): The CRC is a method of error detection and correction that is applied to a certain
field of data. CRC is an efficient method of error detection because the odds of erroneously detecting a correct
payload are low.
Datagram: A logical entity containing an IP header and the IP message contained within. IP protocols
communicate through datagrams, but these are sometimes fragmented on links. Datagrams are sent as packets on
the link layer, and a datagram may be sent as one or many packets.
FIFO (F irst I n, F irst O ut ): A FIFO memory is one in which the first byte to have been written into the memory is the
first one to be read from the read port.
Frame: A unit of data transported on a link layer. In Ethernet, for example, a frame would contain the MAC header,
the IP (or other) packet within, and the Ethernet trailer.
H.110: A TDM bus standard developed by ECTF to provide backward compatibility to existing TDM busses with
more bandwidth and potential for development. H.100 has a total bandwidth of 256 Mbps. On a compact PCI
platform, the name H.110 is used for this bus, which keeps the same logical characteristics but different electrical
ones.
HDLC (H igh-level D ata L ink C ontrol ): An encapsulation protocol that defines specific bit patterns as delimiters and
thus allows transmission of data over a serial link. In the MT92220, HDLC is used to carry variable-length packets
on the H.110 bus.
IP (I nternet P rotocol ): Designed for use in interconnected systems of packet-switched computer communication
networks, IP is the ubiquitous protocol on which the Internet runs. Logically, two machines communicate through IP
datagrams, which are then sent over the link layer as packets. Runs on top of link layers like Ethernet, Packet over
SONET or ATM. Defined in IETF RFC791 & STD5.
Zarlink Semiconductor Inc.
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