SNDCP
Encyclopedia
SNDCP stands for Sub Network Dependent Convergence Protocol.
This is part of layer 3 of a GPRS protocol specification. SNDCP interfaces to the Internet Protocol
at the top, and to the GPRS-specific Logical Link Control
(LLC) protocol at the bottom.
In the spirit of the GPRS specifications, there can be many implementations of SNDCP, supporting protocols such as X.25
. However, in reality, IP (Internet Protocol) is such an overwhelming standard that X.25 has become irrelevant for modern applications, so all implementations of SNDCP for GPRS only support IP as the payload type.
The SNDCP layer comes into the picture, when a PDP Context is established and the Quality of Service
has been negotiated.
Datagrams) into sub-network formats (called SNPDUs).It also performs compression of NPDUs to make for efficient Data transmission. It performs the multiple PDP Context PDU transfers and it also ensures that NPDUs from each PDP Context are transmitted to the LLC layer in sufficient time to maintain the QoS.
This is part of layer 3 of a GPRS protocol specification. SNDCP interfaces to the Internet Protocol
Internet Protocol
The Internet Protocol is the principal communications protocol used for relaying datagrams across an internetwork using the Internet Protocol Suite...
at the top, and to the GPRS-specific Logical Link Control
Logical Link Control
The logical link control data communication protocol layer is the upper sub-layer of the data link layer in the seven-layer OSI reference model...
(LLC) protocol at the bottom.
In the spirit of the GPRS specifications, there can be many implementations of SNDCP, supporting protocols such as X.25
X.25
X.25 is an ITU-T standard protocol suite for packet switched wide area network communication. An X.25 WAN consists of packet-switching exchange nodes as the networking hardware, and leased lines, Plain old telephone service connections or ISDN connections as physical links...
. However, in reality, IP (Internet Protocol) is such an overwhelming standard that X.25 has become irrelevant for modern applications, so all implementations of SNDCP for GPRS only support IP as the payload type.
The SNDCP layer comes into the picture, when a PDP Context is established and the Quality of Service
Quality of service
The quality of service refers to several related aspects of telephony and computer networks that allow the transport of traffic with special requirements...
has been negotiated.
Services offered by SNDCP
The SNDCP layer primarily converts, encapsulates and segments external network formats (like Internet ProtocolInternet Protocol
The Internet Protocol is the principal communications protocol used for relaying datagrams across an internetwork using the Internet Protocol Suite...
Datagrams) into sub-network formats (called SNPDUs).It also performs compression of NPDUs to make for efficient Data transmission. It performs the multiple PDP Context PDU transfers and it also ensures that NPDUs from each PDP Context are transmitted to the LLC layer in sufficient time to maintain the QoS.