IPC Classification

Class code (prefix) Descriptions Number of results
H04L 1/00 Arrangements for detecting or preventing errors in the information received
H04L 1/02 Arrangements for detecting or preventing errors in the information received by diversity reception
H04L 1/04 Arrangements for detecting or preventing errors in the information received by diversity reception using frequency diversity
H04L 1/06 Arrangements for detecting or preventing errors in the information received by diversity reception using space diversity
H04L 1/08 Arrangements for detecting or preventing errors in the information received by repeating transmission, e.g. Verdan system
H04L 1/12 Arrangements for detecting or preventing errors in the information received by using return channel
H04L 1/14 Arrangements for detecting or preventing errors in the information received by using return channel in which the signals are sent back to the transmitter to be checked
H04L 1/16 Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
H04L 1/18 Automatic repetition systems, e.g. van Duuren system
H04L 1/20 Arrangements for detecting or preventing errors in the information received using signal-quality detector
H04L 1/22 Arrangements for detecting or preventing errors in the information received using redundant apparatus to increase reliability
H04L 1/24 Testing correct operation
H04L 5/00 Arrangements affording multiple use of the transmission path
H04L 5/02 Channels characterised by the type of signal
H04L 5/04 Channels characterised by the type of signal the signals being represented by different amplitudes or polarities, e.g. quadriplex
H04L 5/06 Channels characterised by the type of signal the signals being represented by different frequencies
H04L 5/08 Channels characterised by the type of signal the signals being represented by different frequencies each combination of signals in different channels being represented by a fixed frequency
H04L 5/10 Channels characterised by the type of signal the signals being represented by different frequencies with mechanical filters or demodulators
H04L 5/12 Channels characterised by the type of signal the signals being represented by different phase modulations of a single carrier
H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
H04L 5/16 Half-duplex systems; Simplex/duplex switching; Transmission of break signals
H04L 5/18 Automatic changing of the traffic direction
H04L 5/20 Arrangements affording multiple use of the transmission path using different combinations of lines, e.g. phantom working
H04L 5/22 Arrangements affording multiple use of the transmission path using time-division multiplexing
H04L 5/24 Arrangements affording multiple use of the transmission path using time-division multiplexing with start-stop synchronous converters
H04L 5/26 Arrangements affording multiple use of the transmission path using time-division multiplexing combined with the use of different frequencies
H04L 7/00 Arrangements for synchronising receiver with transmitter
H04L 7/02 Speed or phase control by the received code signals, the signals containing no special synchronisation information
H04L 7/04 Speed or phase control by synchronisation signals
H04L 7/06 Speed or phase control by synchronisation signals the synchronisation signals differing from the information signals in amplitude, polarity, or frequency
H04L 7/08 Speed or phase control by synchronisation signals the synchronisation signals recurring cyclically
H04L 7/10 Arrangements for initial synchronisation
H04L 7/027 Speed or phase control by the received code signals, the signals containing no special synchronisation information extracting the synchronising or clock signal from the received signal spectrum, e.g. by using a resonant or bandpass circuit
H04L 7/033 Speed or phase control by the received code signals, the signals containing no special synchronisation information using the transitions of the received signal to control the phase of the synchronising-signal- generating means, e.g. using a phase-locked loop
H04L 9/00 Arrangements for secret or secure communication
H04L 9/06 Arrangements for secret or secure communication the encryption apparatus using shift registers or memories for blockwise coding, e.g. D.E.S. systems
H04L 9/08 Key distribution
H04L 9/10 Arrangements for secret or secure communication with particular housing, physical features or manual controls
H04L 9/12 Transmitting and receiving encryption devices synchronised or initially set up in a particular manner
H04L 9/14 Arrangements for secret or secure communication using a plurality of keys or algorithms
H04L 9/16 Arrangements for secret or secure communication using a plurality of keys or algorithms the keys or algorithms being changed during operation
H04L 9/18 Encryption by serially and continuously modifying data stream elements, e.g. stream cipher systems
H04L 9/20 Pseudorandom key sequence combined element-for-element with data sequence
H04L 9/22 Pseudorandom key sequence combined element-for-element with data sequence with particular pseudorandom sequence generator
H04L 9/24 Pseudorandom key sequence combined element-for-element with data sequence with particular pseudorandom sequence generator sequence produced by more than one generator
H04L 9/26 Pseudorandom key sequence combined element-for-element with data sequence with particular pseudorandom sequence generator producing a nonlinear pseudorandom sequence
H04L 9/28 Arrangements for secret or secure communication using particular encryption algorithm
H04L 9/30 Public key, i.e. encryption algorithm being computationally infeasible to invert and users' encryption keys not requiring secrecy
H04L 9/32 Arrangements for secret or secure communication including means for verifying the identity or authority of a user of the system
H04L 9/34 Bits, or blocks of bits, of the telegraphic message being interchanged in time
H04L 9/36 Arrangements for secret or secure communication with means for detecting characters not meant for transmission
H04L 9/38 Encryption being effected by mechanical apparatus, e.g. rotating cams, switches, keytape punchers
H04L 12/00 Data switching networks
H04L 12/02 Data switching networks - Details
H04L 12/04 Switchboards
H04L 12/06 Answer-back mechanisms or circuits
H04L 12/08 Allotting numbers to messages; Counting characters, words or messages
H04L 12/10 Current supply arrangements
H04L 12/12 Arrangements for remote connection or disconnection of substations or of equipment thereof
H04L 12/14 Charging arrangements
H04L 12/16 Arrangements for providing special services to substations
H04L 12/18 Arrangements for providing special services to substations for broadcast or conference
H04L 12/20 Arrangements for providing special services to substations for converting transmission speed from the inherent speed of a substation to the inherent speed of other substations
H04L 12/22 Arrangements for preventing the taking of data from a data transmission channel without authorisation
H04L 12/24 Arrangements for maintenance or administration
H04L 12/26 Monitoring arrangements; Testing arrangements
H04L 12/28 Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
H04L 12/40 Bus networks
H04L 12/42 Loop networks
H04L 12/43 Loop networks with decentralised control with synchronous transmission, e.g. time division multiplex (TDM), slotted rings
H04L 12/44 Star or tree networks
H04L 12/46 Interconnection of networks
H04L 12/50 Circuit switching systems, i.e. systems in which the path is physically permanent during the communication
H04L 12/52 Circuit switching systems, i.e. systems in which the path is physically permanent during the communication using time division techniques
H04L 12/54 Store-and-forward switching systems
H04L 12/56 Packet switching systems
H04L 12/58 Message switching systems
H04L 12/60 Manual relay systems, e.g. push-button switching
H04L 12/62 Manual relay systems, e.g. push-button switching with perforated tape storage
H04L 12/64 Hybrid switching systems
H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
H04L 12/70 Packet switching systems
H04L 12/403 Bus networks with centralised control, e.g. polling
H04L 12/407 Bus networks with decentralised control
H04L 12/413 Bus networks with decentralised control with random access, e.g. carrier-sense multiple-access with collision detection (CSMA-CD)
H04L 12/417 Bus networks with decentralised control with deterministic access, e.g. token passing
H04L 12/423 Loop networks with centralised control, e.g. polling
H04L 12/427 Loop networks with decentralised control
H04L 12/433 Loop networks with decentralised control with asynchronous transmission, e.g. token ring, register insertion
H04L 12/437 Ring fault isolation or reconfiguration
H04L 12/701 Routing or path finding
H04L 12/703 Route fault prevention or recovery, e.g. rerouting, route redundancy, virtual router redundancy protocol [VRRP] or hot standby router protocol [HSRP]
H04L 12/705 Loop or livelock prevention, e.g. time to live [TTL] or spanning tree
H04L 12/707 Route fault prevention or recovery, e.g. rerouting, route redundancy, virtual router redundancy protocol [VRRP] or hot standby router protocol [HSRP] using path redundancy
H04L 12/709 Route fault prevention or recovery, e.g. rerouting, route redundancy, virtual router redundancy protocol [VRRP] or hot standby router protocol [HSRP] using path redundancy using M+N parallel active paths
H04L 12/711 Route fault prevention or recovery, e.g. rerouting, route redundancy, virtual router redundancy protocol [VRRP] or hot standby router protocol [HSRP] using path redundancy using M:N active or standby paths
H04L 12/713 Route fault prevention or recovery, e.g. rerouting, route redundancy, virtual router redundancy protocol [VRRP] or hot standby router protocol [HSRP] using node redundancy, e.g. VRRP
H04L 12/715 Hierarchical routing, e.g. clustered networks or inter-domain routing
H04L 12/717 Centralised routing
H04L 12/721 Routing procedures, e.g. shortest path routing, source routing, link state routing or distance vector routing
H04L 12/723 Label or tag based routing, e.g. multi-protocol label switching [MPLS] or generalised multi-protocol label switching [GMPLS]
H04L 12/725 Selecting a path with suitable quality of service [QoS]
H04L 12/727 Selecting a path with minimum delay
H04L 12/729 Selecting a path with suitable bandwidth or throughput
H04L 12/733 Selecting a path with minimum length or minimum hop count
H04L 12/735 Disjoint routing, e.g. path disjoint or node disjoint
H04L 12/741 Header address processing for routing, e.g. table lookup
H04L 12/743 Header address processing for routing, e.g. table lookup using hashing techniques
H04L 12/745 Header address processing for routing, e.g. table lookup using longest matching prefix
H04L 12/747 Address caching
H04L 12/749 Address processing over inter-domain or inter-network, e.g. mapping different addresses between IPv6 and IPv4 networks for routing
H04L 12/751 Topology update or discovery
H04L 12/753 Routing tree discovery, e.g. converting from mesh topology to tree topology
H04L 12/755 Topology update consistency, e.g. link state advertisement [LSA], time stamping or sequence numbers in the updates
H04L 12/757 Synchronised activation of routing updates, e.g. delaying or holding routing table updates
H04L 12/759 Dynamic adaptation of update interval, e.g. event-driven updates
H04L 12/761 Broadcast or multicast routing
H04L 12/763 Shortcut routing, e.g. next hop resolution protocol [NHRP]
H04L 12/771 Router architecture
H04L 12/773 Router architecture for supporting layer 3 switching, e.g. IP switching, cell switch relay [CSR] or tag switching
H04L 12/775 Router architecture multiple routing entities, e.g. multiple software or hardware instances
H04L 12/781 Multiprotocol routing, e.g. for protocol adaptation between IPv4 and IPv6 or dual stack
H04L 12/801 Flow control or congestion control
H04L 12/803 Load balancing, e.g. traffic distribution over multiple links
H04L 12/805 Determination of the optimum packet size, e.g. maximum transmission unit [MTU]
H04L 12/807 Calculation or update of the congestion window
H04L 12/811 Bitrate adaptation in active flows
H04L 12/813 Policy-based control, e.g. policing
H04L 12/815 Shaping
H04L 12/819 Leaky bucket
H04L 12/823 Packet dropping
H04L 12/825 Adaptive control, at the source or intermediate nodes, upon congestion feedback, e.g. X-on X-off
H04L 12/827 Adaptive control, at the source or intermediate nodes, upon congestion feedback, e.g. X-on X-off sent by intermediate network nodes
H04L 12/829 Adaptive control, at the source or intermediate nodes, upon congestion feedback, e.g. X-on X-off sent by the destination endpoint
H04L 12/833 Marking packets or altering packet priority upon congestion or for congestion prevention
H04L 12/835 Bitrate adaptation in active flows using buffer capacity information at the endpoints or transit nodes
H04L 12/841 Flow control actions using time consideration, e.g. round trip time [RTT]
H04L 12/851 Traffic type related actions, e.g. QoS or priority
H04L 12/853 Traffic type related actions, e.g. QoS or priority for real time traffic
H04L 12/855 Traffic type related actions, e.g. QoS or priority for signalling traffic, e.g. operations, administration and maintenance [OAM] or acknowledge [ACK] packets
H04L 12/857 Mapping QoS constraints between layers or between different networks
H04L 12/859 Flow control actions based on the nature of the application, e.g. controlling web browsing or e-mail traffic
H04L 12/861 Packet buffering or queuing arrangements; Queue scheduling
H04L 12/863 Queue scheduling, e.g. Round Robin
H04L 12/865 Priority-based scheduling
H04L 12/867 Fair share scheduling
H04L 12/869 Multilevel scheduling; Hierarchical scheduling
H04L 12/873 Bandwidth-aware scheduling
H04L 12/875 Delay-aware scheduling
H04L 12/877 Distribution of residual bandwidth, e.g. distribution of unused bandwidth to best effort traffic [BET]
H04L 12/879 Single buffer operations, e.g. buffer pointers or buffer descriptors
H04L 12/883 Packet storage using a linked list of buffers
H04L 12/885 Jitter compensation buffering
H04L 12/891 Flow control of aggregated links or flows
H04L 12/893 Connection splitting, e.g. IP splitting
H04L 12/901 Ingress point selection by the source endpoint, e.g. Internet service provider [ISP] or point of presence [POP] selection
H04L 12/903 Selection among a plurality of different networks
H04L 12/905 Dynamic network selection or re-selection, e.g. after degradation of quality
H04L 12/911 Network admission control and resource allocation, e.g. bandwidth allocation or in-call renegotiation
H04L 12/913 Reservation actions involving intermediate nodes, e.g. resource reservation protocol [RSVP]
H04L 12/915 Reservation actions involving several network domains, e.g. multilateral agreements or mapping of resources
H04L 12/917 Dynamic resource allocation, e.g. in-call renegotiation requested by the user or upon changing network conditions requested by the network
H04L 12/919 Dynamic resource allocation, e.g. in-call renegotiation requested by the user or upon changing network conditions requested by the network initiated by the source endpoint
H04L 12/923 Dynamic resource allocation, e.g. in-call renegotiation requested by the user or upon changing network conditions requested by the network initiated by the network
H04L 12/925 Reservation of resources at the destination endpoint
H04L 12/927 Allocation of resources based on type of traffic, QoS or priority
H04L 12/931 Switch fabric architecture
H04L 12/933 Switch core, e.g. crossbar, shared memory or shared medium
H04L 12/935 Switch interfaces, e.g. port details
H04L 12/937 Switch control, e.g. arbitration
H04L 12/939 Provisions for redundant switching, e.g. using parallel switching planes
H04L 12/943 Transferring a complete packet or cell from each plane
H04L 12/945 Transferring a part of the packet or cell from each plane, e.g. bit slice
H04L 12/947 Address processing within a device, e.g. using internal ID or tags for routing within a switch
H04L 12/951 Assembling and disassembling of packets, e.g. segmentation and reassembly [SAR] in asynchronous transfer mode [ATM]
H04L 12/953 Packet sequencing arrangements for supporting message reassembly, e.g. packet sequence number
H04L 12/955 Padding or de-padding, e.g. inserting or removing dummy data in or from unused packet segments
H04L 13/00 TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION - Details of the apparatus or circuits covered by groups or
H04L 13/02 TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION - Details of the apparatus or circuits covered by groups or - Details not particular to receiver or transmitter
H04L 13/04 Driving mechanisms; Clutches
H04L 13/06 Tape or page guiding or feeding devices
H04L 13/08 Intermediate storage means
H04L 13/10 Distributors
H04L 13/12 Non-mechanical distributors, e.g. relay distributors
H04L 13/14 Electronic distributors
H04L 13/16 TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION - Details of the apparatus or circuits covered by groups or of transmitters, e.g. code-bars, code-discs
H04L 13/18 TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION - Details of the apparatus or circuits covered by groups or of receivers
H04L 15/00 Apparatus or local circuits for transmitting or receiving dot-and-dash codes, e.g. Morse code
H04L 15/03 Keys structurally combined with sound generators
H04L 15/04 Apparatus or circuits at the transmitting end
H04L 15/06 Apparatus or circuits at the transmitting end with a restricted number of keys, e.g. separate key for each type of code element
H04L 15/08 Apparatus or circuits at the transmitting end with a restricted number of keys, e.g. separate key for each type of code element with a single key which transmits dots in one position and dashes in a second position
H04L 15/10 Apparatus or circuits at the transmitting end with a restricted number of keys, e.g. separate key for each type of code element combined with perforating apparatus
H04L 15/12 Apparatus or circuits at the transmitting end with keyboard co-operating with code-bars
H04L 15/14 Apparatus or circuits at the transmitting end with keyboard co-operating with code-bars combined with perforating apparatus
H04L 15/16 Apparatus or circuits at the transmitting end with keyboard co-operating with code discs
H04L 15/18 Automatic transmitters, e.g. controlled by perforated tape
H04L 15/20 Automatic transmitters, e.g. controlled by perforated tape with optical sensing means
H04L 15/22 Apparatus or circuits for sending one or a restricted number of signals, e.g. distress signals
H04L 15/24 Apparatus or circuits at the receiving end
H04L 15/26 Apparatus or circuits at the receiving end operating only on reception of predetermined code signals, e.g. distress signals, party-line call signals
H04L 15/28 Code reproducing apparatus
H04L 15/30 Writing recorders
H04L 15/32 Perforating recorders
H04L 15/34 Apparatus for recording received coded signals after translation, e.g. as type-characters
H04L 17/00 Apparatus or local circuits for transmitting or receiving codes wherein each character is represented by the same number of equal-length code elements, e.g. Baudot code
H04L 17/02 Apparatus or circuits at the transmitting end
H04L 17/04 Apparatus or circuits at the transmitting end with keyboard co-operating with code-bars
H04L 17/06 Contact operating means
H04L 17/08 Apparatus or circuits at the transmitting end with keyboard co-operating with code-bars combined with perforating apparatus
H04L 17/10 Apparatus or circuits at the transmitting end with keyboard co-operating with code-discs
H04L 17/12 Automatic transmitters, e.g. controlled by perforated tape
H04L 17/14 Automatic transmitters, e.g. controlled by perforated tape with optical sensing means
H04L 17/16 Apparatus or circuits at the receiving end
H04L 17/18 Code selection mechanisms
H04L 17/20 Apparatus or circuits at the receiving end using perforating recorders
H04L 17/22 Apparatus or circuits at the receiving end using mechanical translation and type-bar printing
H04L 17/24 Apparatus or circuits at the receiving end using mechanical translation and type-head printing, e.g. type-wheel, type-cylinder
H04L 17/26 Apparatus or circuits at the receiving end using aggregate motion translation
H04L 17/28 Apparatus or circuits at the receiving end using pneumatic or hydraulic translation
H04L 17/30 Apparatus or circuits at the receiving end using electric or electronic translation
H04L 19/00 Apparatus or local circuits for step-by-step systems
H04L 21/00 Apparatus or local circuits for mosaic printer telegraph systems
H04L 21/02 Apparatus or local circuits for mosaic printer telegraph systems at the transmitting end
H04L 21/04 Apparatus or local circuits for mosaic printer telegraph systems at the receiving end
H04L 23/00 Apparatus or local circuits for telegraphic systems other than those covered by groups
H04L 23/02 Apparatus or local circuits for telegraphic systems other than those covered by groups adapted for orthogonal signalling
H04L 25/00 Baseband systems
H04L 25/02 Baseband systems - Details
H04L 25/03 Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
H04L 25/04 Passive shaping networks
H04L 25/05 Electric or magnetic storage of signals before transmitting or retransmitting for changing the transmission rate
H04L 25/06 Dc level restoring means; Bias distortion correction
H04L 25/08 Modifications for reducing interference; Modifications for reducing effects due to line faults
H04L 25/10 Compensating for variations in line balance
H04L 25/12 Compensating for variations in line impedance
H04L 25/14 Channel dividing arrangements
H04L 25/17 Interpolating arrangements
H04L 25/18 Arrangements for inductively generating telegraphic signals
H04L 25/20 Repeater circuits; Relay circuits
H04L 25/22 Repeaters for converting two wires to four wires; Repeaters for converting single current to double current
H04L 25/24 Relay circuits using discharge tubes or semiconductor devices
H04L 25/26 Circuits with optical sensing means
H04L 25/28 Repeaters using modulation and subsequent demodulation
H04L 25/30 Non-synchronous systems
H04L 25/32 Non-synchronous systems characterised by the code employed
H04L 25/34 Non-synchronous systems characterised by the code employed using three or more different amplitudes, e.g. cable code
H04L 25/38 Synchronous or start-stop systems, e.g. for Baudot code
H04L 25/40 Transmitting circuits; Receiving circuits
H04L 25/42 Transmitting circuits; Receiving circuits using mechanical distributors
H04L 25/44 Transmitting circuits; Receiving circuits using relay distributors
H04L 25/45 Transmitting circuits; Receiving circuits using electronic distributors
H04L 25/46 Transmitting circuits; Receiving circuits using tuning forks or vibrating reeds
H04L 25/48 Transmitting circuits; Receiving circuits characterised by the code employed
H04L 25/49 Transmitting circuits; Receiving circuits using three or more amplitude levels
H04L 25/52 Repeater circuits; Relay circuits
H04L 25/54 Repeater circuits; Relay circuits using mechanical distributors
H04L 25/56 Non-electrical regenerative repeaters
H04L 25/58 Repeater circuits; Relay circuits using relay distributors
H04L 25/60 Regenerative repeaters with electromagnetic switches
H04L 25/62 Repeater circuits; Relay circuits using tuning forks or vibrating reeds
H04L 25/64 Start-stop regenerative repeaters using discharge tubes or semiconductor devices
H04L 25/66 Synchronous repeaters using discharge tubes or semiconductor devices
H04L 25/493 Transmitting circuits; Receiving circuits using three or more amplitude levels by transition coding, i.e. the time-position or direction of a transition being encoded before transmission
H04L 25/497 Transmitting circuits; Receiving circuits using three or more amplitude levels by correlative coding, e.g. partial response coding or echo modulation coding
H04L 27/00 Modulated-carrier systems
H04L 27/01 Equalisers
H04L 27/02 Amplitude-modulated carrier systems, e.g. using on/off keying; Single sideband or vestigial sideband modulation
H04L 27/04 Modulator circuits; Transmitter circuits
H04L 27/06 Demodulator circuits; Receiver circuits
H04L 27/08 Amplitude regulation arrangements
H04L 27/10 Frequency-modulated carrier systems, i.e. using frequency-shift keying
H04L 27/12 Modulator circuits; Transmitter circuits
H04L 27/14 Demodulator circuits; Receiver circuits
H04L 27/16 Frequency regulation arrangements
H04L 27/18 Phase-modulated carrier systems, i.e. using phase-shift keying
H04L 27/20 Modulator circuits; Transmitter circuits
H04L 27/22 Demodulator circuits; Receiver circuits
H04L 27/24 Half-wave signalling systems
H04L 27/26 Systems using multi-frequency codes
H04L 27/28 Systems using multi-frequency codes with simultaneous transmission of different frequencies each representing one code element
H04L 27/30 Systems using multi-frequency codes wherein each code element is represented by a combination of frequencies
H04L 27/32 Carrier systems characterised by combinations of two or more of the types covered by groups , , , or
H04L 27/34 Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
H04L 27/36 Modulator circuits; Transmitter circuits
H04L 27/38 Demodulator circuits; Receiver circuits
H04L 27/144 Demodulator circuits; Receiver circuits with demodulation using spectral properties of the received signal, e.g. by using frequency selective- or frequency sensitive elements
H04L 27/148 Demodulator circuits; Receiver circuits with demodulation using spectral properties of the received signal, e.g. by using frequency selective- or frequency sensitive elements using filters, including PLL-type filters
H04L 27/152 Demodulator circuits; Receiver circuits with demodulation using spectral properties of the received signal, e.g. by using frequency selective- or frequency sensitive elements using controlled oscillators, e.g. PLL arrangements
H04L 27/156 Demodulator circuits; Receiver circuits with demodulation using temporal properties of the received signal, e.g. detecting pulse width
H04L 27/227 Demodulator circuits; Receiver circuits using coherent demodulation
H04L 27/233 Demodulator circuits; Receiver circuits using non-coherent demodulation
H04L 29/00 Arrangements, apparatus, circuits or systems, not covered by a single one of groups
H04L 29/02 Communication control; Communication processing
H04L 29/04 Communication control; Communication processing for plural communication lines
H04L 29/06 Communication control; Communication processing characterised by a protocol
H04L 29/08 Transmission control procedure, e.g. data link level control procedure
H04L 29/10 Communication control; Communication processing characterised by an interface, e.g. the interface between the data link level and the physical level
H04L 29/12 Arrangements, apparatus, circuits or systems, not covered by a single one of groups characterised by the data terminal
H04L 29/14 Counter-measures to a fault