Standard Terms and Abbreviations for CESoP

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AAL0 (ATM Adaption Layer 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". 
AAL5 (ATM Adaption Layer 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-layer0
ADPCM (Adaptive Differential Pulse Code Mode): 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 (Address Resolution Protocol):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.
CESoP (Circuit Emulation Service over Packet): Trunking of TDM data between two points. Providing a method to transport T1/E1 or T3/E3 streams over an IP network. The service is the same CES as has been in the industry for some time, the transport layer is IP which is a new technology. This is similar to ATM CBR service.
Channel: A data stream of a given nature mapped over a connection is considered a channel. For example, a PCM data stream mapped over an RTP connection would be a single channel, even if that data stream interleaved more than 1 bearer in each packet. In like manner, any set of payload types that are all destined to the same HDLC endpoint would also be considered a channel.
CLIP (Classical 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.
Connection: A link between two end-points that is unique through some look-up method, either through source & destination IP addresses and UDP ports, through those plus RTP SSRC, and possibly RTP SSRC
CPU (Central Processing Unit)
CRC (Cyclis Redundancy Check): 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 First In, First Out): 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 (High-Level Data Link Control): An encapsulation protocol that defines specific bit patterns as delimiters and thus allows transmission of data over a serial link. In the MT92210, HDLC is used to carry variable-length packets on the H.110 bus.
IP (Internet Protocol): 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.
Jitter: The effect on arriving packets that retards or advances the packet timing relative to the average arrival time.
Jitter buffers: A hardware buffer that is used to remove jitter from an incoming stream. The buffer size is important in that it has to be big enough to ensure that no packets are lost due to late packets and that has to be small enough to minimize the latency in the system.
LANE (Local Area Network Emulation): LANE is a method for emulating Ethernet behavior over ATM AAL5. It takes over the behavior of the MAC layer in Ethernet networks.
Latency: The time or delay in a network. This accounts for PDV and must be accomadated in the jitter buffers.
LLC (Logical Link Control): The LLC method allows multiplexing of multiple protocols over a single ATM VC. LLC headers are 3 bytes.
MAC (Media Access Control): The MAC layer is concerned with the control of access to a medium shared between two or more entities. It is a control layer for Ethernet.
OC-3 (Optical Carrier level-3): A SONET channel that carries a bandwidth of 155.55 Mbps.
Packet: The "data" unit carried on a link layer. A packet, on an IP network, consists of an entire IP datagram or a fragment of a datagram.
PCM (Pulse Code Mulation): PCM is the basic method of encoding an analog voice signal into digital form using8-bit samples. Defined by the ITU standard G.711.
PDV: Packet Delay Variation. RTP packets arrive with a certain delay with respect to when they were sent. PDV is a measure of how much that delay varies on an xxPCM channel. PDV measures the peak-to-peak packet delay throughout the network. PDV is only relevant on CBR connections.
PHY (PHYsical layer)
PLL (Phase Lock Loop): A phase lock loop is a component that generates an output clock by synchronizing itself to an input clock. PLLs are often used to multiply the frequency of clocks.
POS (Packet Over SONET): A means of transporting packets over a SONET link with minimal overhead in a point-to-point connection. POS uses PPP as its link protocol.
POS-PHY: A bus standard for connectiing Packet Over SONET link layer devices to PHYsical layer ones. POS-PHY level 2 was based loosely on UTOPIA level 2.
POTS (Plain Old Telephone Service): The ubiquitous, 64 kbps phone service widely deployed in today's phone networks.
PPP (Point-to-Point Protocol): A link protocol that allows for transport of many network protocols over a point-to-point link. PPP has very little overhead (1 or 2 bytes per packet), making it very attractive for some applications.
RAM (Random Access Memory): RAM is the main memory in the computer. It is called "random" because any random address can be accessed in an equal amount of time.
RTCP (Real-Time Control Protocol): The control protocol for RTP, RTCP is used for control and diagnostic on RTP sessions. Like RTP, RTCP typically runs on top of UDP and is defined in the IETF RFC1889.
RTP (Real-Time Protocol): A transport protocol designed to provide end-to-end delivery services for data withreal-time characteristics. RTP typically runs on top of UDP. Defined in the IETF RFC1889.
SNAP (Sub Network Access Protocol): A SNAP header consists of 5 bytes, three bytes of OUI (Organizationally Unique Identifier) and 2 bytes of PID (Protocol IDentifier). The OUI defines which organization administers the PID that follows. The value of 000000h in the OUI means that the PID is defined as an EtherType.
TCP (Transmission Control Protocol): A transport layer, TCP is a highly reliable host-to-host protocol that guarantees packet delivery, non-duplicated and in order. TCP runs on top of IP. Defined in IETF RFC791 & STD7.
TDM (Time Dividion Multiplexing): TDM busses carry voice data divided according to frames. In a single 125 us frame, the TDM bus will have carried one byte from each channel it contains.
Time Slot: The term time slot is often used to define a combination of a time slot and a stream on the H.100 bus. Thus a time slot would represent a single 8-bit slot every 125 us on the TDM bus. Time slot/Stream numbers are numbered 0 to 4095 according to the following equation: time slot * 32 + stream. On reduced-frequency TDM streams, certain time slots become unusable. For streams running on a 4 MHz clock, time slots are numbered 0 to 63, and the equations to determine TSSTs are the following: in the TX TDM, TSST = (time slot * 2 + 1) * 32 + stream, and in the RX TDM, TSST = (time slot * 2) * 32 + stream. In like manner, for streams running on a 2 MHz clock, time slots are numbered 0 to 31, and the equations are: in the TX TDM, TSST = (time slot * 4 + 3) * 32 + stream, and in the RX TDM, TSST = (time slot * 4) * 32 + stream.
UDP (User Datagram Protocol): A transport layer, UDP provides a protocol for applications to communicate with a minimum of overhead. UDP does not guarantee packet delivery or ordering. UDP runs on top of IP. Defined in IETF RFC768 & STD6.
UTOPIA (Universal Test and OPerations Interface for ATM):The electrical interface on which ATM cells are passed.
VC (Virtual Circuit): VC define a point-to-point connection between two nodes in a network. A single ATM cellcarries data that belongs to a single VC.
VCI (Virtual Channel Identifier): This is the label given to an ATM VC to identify it and determine its destination. The VCI is a 16-bit number that is included in the header of an ATM cell.
VPI (Virtual Path Identifier): A virtual path determines the way an ATM cell should be routed. The VPI is an 8-bit (in UNI) or 12-bit (in NNI) number that is included in the header of an ATM cell.
WATOMIC: An uninterruptable Write operation.


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