C:\WINWORD\CCITTREC.DOT THE DRAWINGS CONTAINED IN THIS RECOMMENDATION HAVE BEEN DONE IN AUTOCAD. ANNEX A (to Recommendation X.75) Definition of symbols for Annexes B, C and D A.1 General This annex contains the definitions for the symbols to be used in annexes B, C and D. Annex B defines the states of the X/Y interface and the transitions between states in the normal case, while Annex C contains the full definition of actions, if any, to be taken on the receipt of packets by an STE. Annex D describes the actions taken by the STE on time–outs, if any, in the packet layer. A.2 Symbol definition of the state diagrams Figure A–1/X.75 - CCITT 19172 A.3 Order definition of the state diagrams For the sake of clarity, the normal procedure at the interface is described in a number of small state diagrams. In order to describe the nor- mal procedure fully, it is necessary to allocate a priority to the different fig- ures and to relate a higher order diagram with a lower one. This has been done by the following means: – The figures are arranged in order of priority with Figure A–2/X.75 (restart) having the highest priority and subsequent figures having lower priority. Priority means that when a packet belonging to a higher order diagram is transferred, that diagram is applicable and the lower order one is not. – The relation with a state in a lower order diagram is given by includ- ing that state inside an ellipse in the higher order diagram. A.4 Symbol definition of the action tables The entries given in Tables C–1/X.75 to C–5/X.75 and D–1/X.75 (see Annexes C and D) indicate the action, if any, to be taken by an STE on receipt of any kind of packet, and the state the STE enters, which is given in parenthesis, following the action taken. ANNEX B (to Recommendation X.75) State diagrams for the packet layer interface between STEs for normal cases Figure B–1/X.75 - CCITT 19180 Figure B–2/X.75 - CCITT 19190 et CCITT 19200 Figure B–3/X.75 - CCITT 19180 Figure B–4/X.75 - CCITT 19210 ANNEX C (to Recommendation X.75) Actions taken by the STE on receipt of packets in a given state of the packet layer X/Y interface Note – Actions are specified for STE–Y only. STE–X should follow the same procedure. TABLE C–1/X.75 Action taken by STE–Y on receipt of packets State of the interface as perceived by STE–Y Packet received by STE–Y Any state Any packet with unassigned logical channel (see Note) Any packet with less than 2 octets DISCARD Any packet with an incorrect gen- eral format identifier Any packet with correct general format identifier and assigned logi- cal channel (see Note) (See Table C–2/X.75) DISCARD STE–Y discards the received packet and takes no subsequent action. Note – Assigned logical channel includes the case where bits 1 to 4 of octet 1 and bits 1 to 8 of octet 2 are all 0s. TABLE C–2/X.75 Action taken by STE–Y on receipt of packets in a given state: restart State of the interface as perceived by STE–Y Packet layer STE–X restart STE–Y restart Packet received by STE–Y ready r1 request r2 request r3 Restart request NOR- MAL (r2) DIS- CARD (r2) NOR- MAL (r1) Restart confirmation ERROR (r3) ##17 ERROR (r3) (see Note 1) ##18 NOR- MAL (r1) Restart request or confirmation with bit 1 to 4 of octet 1 or bit 1 to 8 of octet 2 0 ERROR (r3) (see Note 1) ##41 Data, interrupt, flow control, reset, call set–up or clear when both logical channel number and logical channel group number are not all 0s (See Table C–3/ X.75) ERROR (r3) (see Note 1) ##18 DIS- CARD (r3) Packet having a packet type identifier which is shorter than 1 octet or is incompatible with the ones defined in § 4 of the text when both logical chan- nel number and logical channel group number are not all 0s ERROR (r3) (see Note 1) ##38 or ##33 Data, interrupt, flow control, reset, call set up, clear, packet having a packet type identifier which is shorter than 1 octet or is incompatible with the ones defined in § 4 of the text when both logical channel number and logical channel group number are all 0s DIS- CARD (r1) DIS- CARD (r2) DIS- CARD (r3) NORMAL The action taken by STE–Y follows the normal procedures as defined in § 3 of the text (see Note 2). DISCARD STE–Y discards the received packet and takes no subsequent action. ERROR STE–Y discards the received packet and indicates restarting with “network congestion” cause and decimal diagnostic value ##n. Note 1 – If STE–Y issues a restart request packet as a result of an error con- dition in state r2, it should follow the actions described in Annex D. Note 2 – In the two following error situations the STE will invoke the ERROR (r3) procedure: a) a restart request packet or restart confirmation packet received in state r3 exceeds the maximum permitted length, is too short or (where detec- tion of non–octet alignment is made at packet layer) is not octet aligned; diagnostic values ##39, ##38 and ##82 respectively are used. b) a restart request packet received in state r1 exceeds the maximum permit- ted length, is too short or (where detection of non–octet alignment is made at packet layer) is not octet aligned; diagnostic values ##39, ##38 and ##82 respectively, are used. TABLE C–3/X.75 Action taken by STE–Y on receipt of packets specifying an assigned logical channel in a given state: call establishment and clearing State of the inter- face as perceived by STE–Y Packet layer ready r1 Packet received by STE–Y Read y p1 STE–X call request p2 STE–Y call request p3 Data transf er p4 STE–X clear request p6 STE–Y clear request p7 Call request NOR MAL (p2) ERRO R (p7) ## 21 ERRO R (p7) ## 116 ERR OR (p7) ## 23 ERRO R (p7) (see Note 1) ## 25 ERRO R (p7) ## 26 Call connected ERR OR (p7) ## 20 ERRO R (p7) ## 21 NOR- MAL (p4) (see Note 2) ERR OR (p7) ## 23 ERRO R (p7) (see Note 1) ## 25 DIS- CARD (p7) Clear request NOR MAL (p6) NOR- MAL (p6) NOR- MAL (p6) NOR MAL (p6) DIS- CARD (p6) NOR- MAL (p1) Clear confirma- tion DIS- CAR D (p1) ERRO R (p7) ## 21 ERRO R (p7) ## 22 ERR OR (p7) ## 23 ERRO R (p7) (see Note 1) ## 25 NOR- MAL (p1) Data, interrupt, flow control or reset ERR OR (p7) ## 20 ERRO R (p7) ## 21 ERRO R (p7) ## 22 ERRO R (p7) (see Note 1) ## 25 Restart request or confirmation with bit 1 to 4 of octet 1 or bit 1 to 8 of octet 2¹ 0 ERR OR (p7) ## 41 ERRO R (p7) ## 41 ERRO R (p7) ## 41 (See Table C-4/ X.75) ERRO R (p7) (see Note 1) ## 41 DISCA RD (p7) Packet having a packet type identi- fier which is shorter than 1 octet or is incom- patible with the ones defined in § 4 of the text ERR OR (p7) ## 38 or ## 33 ERRO R (p7) ## 38 or ## 33 ERRO R (p7) ## 38 or ## 33 ERRO R (p7) (see Note 1) ## 38 or ##33 NORMAL The action taken by STE–Y follows the normal procedures as defined in § 3 of the text. However, if an error condition specified in Annex F occurs, STE–Y discards the received packet and indicates clearing with the cause and diagnostic codes specified in Annex F. DISCARD STE–Y discards the received packet and takes no subsequent action. ERROR STE–Y discards the received packet and indicates clearing with “network congestion” cause and decimal diagnostic value ## n. Note 1 – If STE–Y issues a clear request packet as a result of an error condi- tion in state p6, it should follow the actions described in Annex D. Note 2 – The ERROR (p7) procedure is invoked if STE–Y receives a call connected packet in response to a call request packet from STE–Y request- ing the fast select facility with restriction on response. TABLE C–4/X.75 Action taken by STE–Y on receipt of packets specifying an assigned logical channel in a given state: reset State of the inter- faceas perceived by STE–Y Data transfer p4 Packet received by STE–Y Flow control ready d1 STE–X reset request d2 STE–Y reset request d3 Reset request NORMAL (d2) DISCARD (d2) NORMAL (d1) Reset confirma- tion ERROR (d3) ## 27 ERROR (d3) ## 28 NORMAL (d1) Data, interrupt or flow control (See Table C–5/ X.75) ERROR (d3) ## 28 DISCARD (d3) Restart request or confirmation with bit 1 to 4 of octet 1 or bit 1 to 8 of octet 2 ¹ 0 ERROR (d3) ## 41 ERROR (d3) (see Note 1) ## 41 Packet having a packet type iden- tifier which is shorter than 1 octet or is incompatible with the ones defined in § 4 of the text ERROR (d3) ## 38 or ## 33 ERROR (d3) (see Note 1) ## 38 or ## 33 DISCARD (d3) Invalid packet type on a perma- nent virtual cir- cuit ERROR (d3) ## 35 ERROR (d3) (see Note 1) ## 35 NORMAL The action taken by STE–Y follows the normal procedures as defined in § 3 of the text (see Note 2). DISCARD STE–Y discards the received packet and takes no subsequent action. ERROR STE–Y discards the received packet and indicates resetting with “network congestion” cause and decimal diagnostic value ## n. Note 1 – If STE–Y issues a reset request packet as a result of an error condi- tion in state d2, it should follow the actions described in Annex D. Note 2 – In the following error situations the STE will invoke the ERROR (d3) procedure: the received packet exceeds the maximum permitted length, is too short or (where detection of non–octet alignment is made at packet layer) is not octet aligned; diagnostic values ## 39, ## 38 and ## 82 respec- tively are used. TABLE C–5/X.75 Action taken by receipt of packets specifying an assigned logical channel in a given state: data, interrupt or flow control State of the interfaceas per- ceived by STE– Y Flow control ready d1 Packet received by STE–Y Not inter- rupted i1 STE–X interrupt request i2 STE–Y interrupt request i3 STE–X and Y interrupt request i4 Interrupt NOR- MAL (i2) DIS- CARD (i2) or ERROR (d3) (see Note 1) ## 44 NOR- MAL (i4) DIS- CARD (i4) or ERROR (d3) (see Note 1) ## 44 Interrupt con- firmation DIS- CARD (i1) DIS- CARD (i2) NOR- MAL (i1) NOR- MAL (i2) Data with out of sequence P(S) or P(S) outside of win- dow ERROR (d3) ## 1 ERROR (d3) ## 1 ERROR (d3) ## 1 ERROR (d3) ## 1 Data with M bit violation ERROR (d3) ## 103 ERROR (d3) ## 103 ERROR (d3) ## 103 ERROR (d3) ## 103 Data with inconsistent Q bit setting NOR- MAL (i1) or ERROR (d3) ## 83 (see Note 3) NOR- MAL (i2) or ERROR (d3) ## 83 (see Note 3) NOR- MAL (i3) or ERROR (d3) ## 83 (see Note 3) NOR- MAL (i4) or ERROR (d3) ## 83 (see Note 3) Data or flow control with invalid P(R) ERROR (d3) ## 2 ERROR (d3) ## 2 ERROR (d3) ## 2 ERROR (d3) ## 2 A first data packet after entering state d1 with P(S) 0 ERROR (d3) ## 1 ERROR (d3) ## 1 ERROR (d3) ## 1 ERROR (d3) ## 1 When modulo 128 numbering is used, a flow control or data packet with octet 4 shorter than 1 octet ERROR (d3) ## 38 ERROR (d3) ## 38 ERROR (d3) ## 38 ERROR (d3) ## 38 Valid data or flow control NOR- MAL (i1) NOR- MAL (i2) NOR- MAL (i3) NOR- MAL (i4) NORMAL The action taken by STE–Y follows the normal procedures as defined in § 3 of the text (see Note 2). DISCARD STE–Y discards the received packet and takes no subsequent action. ERROR STE–Y discards the received packet and indicates reset with “net- work congestion” cause and decimal diagnostic value ## n. Note 1 – According to § 3.3.5 an STE receiving a further interrupt packet in the time between receiving one interrupt packet and transferring the inter- rupt confirmation may either discard this interrupt packet or reset the virtual call or the permanent virtual circuit. Note 2 – In the following error situations the STE will invoke the ERROR (d3) procedure: the received packet exceeds the maximum permitted length, is too short or (where detection of non–octet alignment is made at packet layer) is not octet aligned; diagnostic values ## 39, ## 38 and ## 82 respec- tively are used. Note 3 – According to § 3.3.4 if an STE detects that the value of the Q bit has changed within a packet sequence it may reset the virtual call or perma- nent virtual circuit. ANNEX D (to Recommendation X.75) Actions taken by the STE on time–outs in the packet layer Under certain circumstances, the STE Y/X is required to respond to a packet from the STE X/Y within a stated maximum time. If any of these maximum times are exceeded, a time–out in the STE X/Y will initiate the actions sum- marized in Tables D–1/X.75 and D–2/X.75. Therefore, this must be taken into account in the STE design. TABLE D–1/X.75 STE X/Y time–outs (first time) Time -out num ber Time –out value Stat e of the logi cal cha nnel Started when Normally terminated when Actions to be taken the first time the time–out expires Toward STE Y/X Toward net- work T30 180 sec r2/ r3 STE X/ Y issues a restart request packet STE X/Y leaves the r2/r3 state (i.e., a restart con- firmation or restart request packet is received) STE X/Y signals a restart request packet (net- work conges- tion, ## 52) again, and restarts time– out T30 For perma- nent virtual circuits, the STE signals a reset request packet (net- work conges- tion, ## 52) T31 200 sec p2/ p3 STE X/ Y issues a call request packet STE X/Y leaves the p2/p3 state (e.g., a call connected, clear request or call request packet is received) STE X/Y enters the p6/ p7 state sig- nalling a clear request packet (net- work conges- tion, ## 49) STE X/Y signals a clear request packet (net- work conges- tion, ## 49) T32 180 sec d2/ d3 STE X/ Y issues a reset request packet STE X/Y leaves the d2/d3 state (e.g., a reset confirmatio n or reset request packet is received) STE X/Y signals a reset request packet (net- work conges- tion, ## 51) again and restarts time– out T32 STE X/Y signals reset request packet (net- work conges- tion, ## 51) T33 180 sec p6/ p7 STE X/ Y issues a clear request packet STE X/Y leaves the p6/p7 state (e.g., a clear con- firmation or clear request packet is received) STE X/Y signals a clear request packet (net- work conges- tion, ## 50) again, and restarts time– out T33 TABLE D–2/X.75 STE X/Y time–outs (second time) Time–out num- ber Actions to be taken the second time the time–out expires Toward STE Y/X Toward network T30 STE X/Y enters the r1 state Note – Further actions may be initiated at higher level For permanent virtual cir- cuits, STE X/Y signals a reset request packet (net- work congestion, ## 52) T31 (Not possible; T31 is not restarted after it has expired) T32 For virtual calls, STE X/Y enters the p6/p7 state sig- nalling a clear request packet (network conges- tion, ## 51) For permanent virtual cir- cuits, STE X/Y enters the d1 state For virtual calls, STE X/Y signals a clear request packet (network conges- tion, ## 51) For permanent virtual cir- cuits, STE X/Y signals a reset request packet (net- work congestion, ## 51) T33 STE X/Y enters the p1 state. ANNEX E (to Recommendation X.75) Coding of network generated diagnostic fields in X.75 clear, reset and restart packets TABLE E–1/X.75 (See Notes 1, 2, 3 and 9) Bits Diagnostics 8 7 6 5 4 3 2 1 Deci mal No additional information 0 0 0 0 0 0 0 0 0 Invalid P(S) 0 0 0 0 0 0 0 1 1 Invalid P(R) 0 0 0 0 0 0 1 0 2 0 0 0 0 1 1 1 1 15 Packet type invalid 0 0 0 1 0 0 0 0 16 For state r1 0 0 0 1 0 0 0 1 17 For state r2 0 0 0 1 0 0 1 0 18 For state r3 0 0 0 1 0 0 1 1 19 For state p1 0 0 0 1 0 1 0 0 20 For state p2 0 0 0 1 0 1 0 1 21 For state p3 0 0 0 1 0 1 1 0 22 For state p4 0 0 0 1 0 1 1 1 23 For state p5 0 0 0 1 1 0 0 0 24 For state p6 0 0 0 1 1 0 0 1 25 For state p7 0 0 0 1 1 0 1 0 26 For state d1 0 0 0 1 1 0 1 1 27 For state d2 0 0 0 1 1 1 0 0 28 For state d3 0 0 0 1 1 1 0 1 29 0 0 0 1 1 1 1 1 31 Packet not allowed 0 0 1 0 0 0 0 0 32 Unidentifiable packet 0 0 1 0 0 0 0 1 33 Call on one way logical channel (Note 4) 0 0 1 0 0 0 1 0 34 Invalid packet type on a per- manent virtual circuit 0 0 1 0 0 0 1 1 35 Packet on unassigned logical channel 0 0 1 0 0 1 0 0 36 Reject not subscribed to (Note 4) 0 0 1 0 0 1 0 1 37 Packet too short 0 0 1 0 0 1 1 0 38 Packet too long 0 0 1 0 0 1 1 1 39 Invalid general format identi- fier 0 0 1 0 1 0 0 0 40 Restart with non–zero in bits 1–4, 9–16 0 0 1 0 1 0 0 1 41 Packet type not compatible with facility/utility (Note 5) 0 0 1 0 1 0 1 0 42 Unauthorized interrupt con- firmation 0 0 1 0 1 0 1 1 43 Unauthorized interrupt 0 0 1 0 1 1 0 0 44 Unauthorized reject (Note 4) 0 0 1 0 1 1 0 1 45 0 0 1 0 1 1 1 1 47 TABLE E–1/X.75 (continued) Bits Diagnostics 8 7 6 5 4 3 2 1 Deci mal Time expired 0 0 1 1 0 0 0 0 48 For incoming call/call request (Note 6) 0 0 1 1 0 0 0 1 49 For clear indication/request (Note 6) 0 0 1 1 0 0 1 0 50 For reset indication/request (Note 6) 0 0 1 1 0 0 1 1 51 For restart indication/request (Note 6) 0 0 1 1 0 1 0 0 52 0 0 1 1 1 1 1 1 63 Call set–up or clearing prob- lem 0 1 0 0 0 0 0 0 64 Facility/utility code not allowed (Note 5) 0 1 0 0 0 0 0 1 65 Facility/utility parameter not allowed (Note 5) 0 1 0 0 0 0 1 0 66 Invalid called address 0 1 0 0 0 0 1 1 67 Invalid calling address 0 1 0 0 0 1 0 0 68 Invalid facility length 0 1 0 0 0 1 0 1 69 Incoming call barred 0 1 0 0 0 1 1 0 70 No logical channel available 0 1 0 0 0 1 1 1 71 Call collision 0 1 0 0 1 0 0 0 72 Duplicate facility/utility requested (Note 5) 0 1 0 0 1 0 0 1 73 Non–zero address length 0 1 0 0 1 0 1 0 74 Non–zero facility length 0 1 0 0 1 0 1 1 75 Facility/utility not provided when expected (Note5) 0 1 0 0 1 1 0 0 76 Invalid CCITT–specified DTE facility 0 1 0 0 1 1 0 1 77 0 1 0 0 1 1 1 1 79 Miscellaneous 0 1 0 1 0 0 0 0 80 Improper cause code from DTE/STE (Note 7) 0 1 0 1 0 0 0 1 81 Octet non–aligned 0 1 0 1 0 0 1 0 82 Inconsistent Q bit setting 0 1 0 1 0 0 1 1 83 NUI problem 0 1 0 1 0 1 0 0 84 0 1 0 1 1 1 1 1 95 Inter–network call set–up or clearing problem 0 1 1 0 0 0 0 0 96 Unknown calling DNIC 0 1 1 0 0 0 0 1 97 TNIC mismatch 0 1 1 0 0 0 1 0 98 Call identifier mismatch 0 1 1 0 0 0 1 1 99 Negotiation error in utility parameter value 0 1 1 0 0 1 0 0 100 Invalid utility length 0 1 1 0 0 1 0 1 101 Non–zero utility length 0 1 1 0 0 1 1 0 102 M bit violation 0 1 1 0 0 1 1 1 103 0 1 1 0 1 1 1 1 111 TABLE E–1/X.75 (continued) Bits Diagnostics 8 7 6 5 4 3 2 1 Deci mal Inter–network problem 0 1 1 1 0 0 0 0 112 Remote network problem 0 1 1 1 0 0 0 1 113 Inter–network protocol prob- lem 0 1 1 1 0 0 1 0 114 Inter–network link out of order 0 1 1 1 0 0 1 1 115 Inter–network link busy 0 1 1 1 0 1 0 0 116 Transit network facility prob- lem 0 1 1 1 0 1 0 1 117 Remote network facility problem 0 1 1 1 0 1 1 0 118 Inter–network routing prob- lem 0 1 1 1 0 1 1 1 119 Temporary routing problem 0 1 1 1 1 0 0 0 120 Unknown called DNIC 0 1 1 1 1 0 0 1 121 Maintenance action 0 1 1 1 1 0 1 0 122 0 1 1 1 1 1 1 1 127 Reserved for network specific diagnostic information (Note 8) 1 0 0 0 0 0 0 0 128 1 1 1 1 1 1 1 1 255 Note 1 – Not all diagnostic codes need apply to a specific network, but those used are coded as in the table. Note 2 – A given diagnostic need not apply to all packet types (i.e. reset request, clear request and restart request packets). Note 3 – The first diagnostic in each grouping is a generic diagnostic and can be used in place of the more specific diagnostics within the grouping. The decimal 0 diagnostic code can be used in situations where no additional information is available. Note 4 – Only generated at a user interface (see Recommendation X.25). Note 5 – When associated with the cause “Network congestion”, this indi- cates a utility problem; when associated with any other valid cause (see Tables 13/X.75, 15/X.75 and 17/X.75) this indicates a facility problem at a user interface. Note 6 – When associated with the cause “Network congestion”, this indi- cates an X.75 packet timer problem; when associated with any other valid cause (see Tables 13/X.75, 15/X.75 and 17/X.75) this indicates a packet timer problem at a user interface. Note 7 – When associated with the cause “Network congestion”, this indi- cates an invalid cause detected on an X.75 link; when associated with any other valid cause (see Tables 13/X.75, 15/X.75 and 17/X.75) this indicates an invalid cause detected at a user interface. Note 8 – When the associated cause is “Network congestion”, diagnostic codes in this range may by bilateral agreement between Administrations, be transferred across an X.75 link. However, the receiving network will alter such values, as described in §§4.2.3.2, 4.4.3.2 or 4.5.1.2 as appropriate, before passing them to another network or across a user interface. Note 9 – When the associated cause is “Network congestion”, diagnostic codes in the range 1 to 111 will be altered by the receiving network, as described in §§ 4.2.3.2 , 4.4.3.2 or 4.5.1.2 as appropriate, before passing them to another network or across a user interface. ANNEX F (to Recommendation X.75) Association of error conditions with cause and diagnostic codes a) Call request packet Error condition Cause Specific diagnos- tics (see Note3 of Annex E) 1. Not octet aligned packet (where detection of non–octet alignment is made at packet level if implemented; see § 3) Network conges- tion ## 82 2. Address contains a non–BCD digit Network conges- tion ## 67, 68 3. Address less than four digits Network conges- tion ## 67, 68 4. Bit 8 of the octet which indi- cates the facility length field not set to 0 Network conges- tion ## 69 5. No combination of utilities could equal utility length Network conges- tion ## 101 6. Facility or utility length larger than remainder of packet Network conges- tion ## 38 7. Utility value conflicts (e.g., a particular combination not sup- ported) Network conges- tion ## 66 8. Utility code not allowed Network conges- tion ## 65 9. Utility value not allowed or invalid Network conges- tion ## 66 10. Utility expected and not pro- vided Network conges- tion ## 76 11. Packet too short Network conges- tion ## 38 12. Address length larger than remainder of packet Network conges- tion ## 38 13. Call user data larger than 16, or 128 octets in case of fast select facility Network conges- tion ## 39 14. Class coding of the utility cor- responding to a length of parame- ter larger than remainder of packet Network conges- tion ## 101 15. Utility code (except TNIC and RPOA) repeated Network conges- tion ## 73 16. Duplicate TNIC Network conges- tion ## 66 17. Unknown calling network identification Network conges- tion ## 97 18. Bits 7 or 8 of the utility length field octet not set to 0 Network conges- tion ## 101 19. Unknown number Not obtainable ## 67 20. Incoming call barred Access barred ## 70 21. Closed user group protection Access barred ## 65 Error condition Cause Specific diagnos- tics (see Note 3 of Annex E) 22. Reverse charging rejected Reverse charging acceptance not subscribed ## 0 23. Fast select rejected Fast select accep- tance not sub- scribed ## 0 24. National address smaller than national address format permits Not obtainable ## 67, 68 25. National address larger than national address format permits Not obtainable ## 67, 68 26. Called DTE out of order Out of order ## 0 ## greater than 127 27. No logical channel available Number busy ## 71 28. Call collision Number busy ## 71, 72 29. The remote DTE/DCE inter- face does not support a function or a facility request Incompatible destination ## 0 30. Procedure error at the remote DTE/DCE interface Remote proce- dure error (see Annex E) 31. Network congestion or fault condition within the network Network conges- tion ## 0 ## greater than 127 (see Note 8 to Annex E) 32. Planned maintenance activity within the network Network conges- tion ## 122 33. Network fault condition detected other than at the local STE–X/Y interface Network conges- tion ## 113 34. X.75 protocol error detected other than at the local STE–X/Y interface Network conges- tion ## 114 35. No inter–Administration ser- vice agreement is recorded for calls from the calling network to the called network Access barred ## 119 36. No inter–Administration ser- vice agreement is recorded for calls from the calling network to the called network using the rout- ing indicated Access barred ## 119 37. The inter–Administration ser- vice agreement does not permit calls using the requested facili- ty(ies) from the calling network to the called network Incompatible destination ## 118 Error condition Cause Specific diagnos- tics (see Note 3 of Annex E) 38. The routing process is unable to determine any suitable outgoing link for the called network Not obtainable ## 121 39. The routing process is unable to determine a suitable outgoing link with a free logical channel Network conges- tion ## 116 40. Call collision is detected on the selected outgoing link Network conges- tion ## 116 41. The routing indicated in the received call request packet is too long for an overall routing con- forming to X.110 to be provided [e.g., because alternative routing has already been used] Network conges- tion ## 120 42. The routing indicated in the received call request packet can- not be extended to provide an overall routing in conformance with X.110 [e.g., because the prior use of alternative routing means that a circular routing would be formed] Network conges- tion ## 120 43. Each of the suitable outgoing links determined by the routing process is subject to an unplanned outage Network conges- tion ## 115 44. The routing process is unable to determine a suitable operational outgoing link supporting the requested facility(ies) Network conges- tion ## 117 45. The routing process is unable to determine a suitable operational outgoing link supporting the parameter value of a requested facility Network conges- tion ## 117 46. None of the suitable outgoing links determined by the routing process is operational, and at least one is subject to a planned outage for essential maintenance Network conges- tion ## 122 47. Requested RPOA out of order RPOA out of order ## 0 48. Requested RPOA invalid or not supported RPOA out of order ## 119 49. NUI utility value invalid/ unsupported or NUI utility required but absent Access barred ## 84 Note – Error conditions 19 to 30 are examples for problems related to the destination network. b) Call connected packet Error condition Cause Specific diagnos- tics (see Note 3 of Annex E) 1. Not octet aligned packet (where detection of non–octet alignment is made at packet level if implemented; see § 3) Network conges- tion ## 82 2. Address contains a non–BCD digit Network conges- tion ## 67, 68 3. Address less than four digits Network conges- tion ## 67, 68 4. Bit 8 of the octet which indi- cates the facility length field not set to 0 Network conges- tion ## 69 5. No combination of utilities could equal utility length Network conges- tion ## 101 6. Facility or utility length larger than remainder of packet Network conges- tion ## 38 7. Utility value conflicts (e.g., a particular combination not sup- ported) Network conges- tion ## 66 8. Utility code not allowed Network conges- tion ## 65 9. Utility value not allowed or invalid Network conges- tion ## 66 10. Utility expected and not pro- vided Network conges- tion ## 76 11. Packet too short Network conges- tion ## 38 12. Address length larger than remainder of packet Network conges- tion ## 38 13. Call user data larger than 128 octets in case of fast select facility Network conges- tion ## 39 14. Call user data present (if fast select facility not requested) Network conges- tion ## 39 15. Class coding of the utility cor- responding to a length of parame- ter larger than remainder of packet Network conges- tion ## 101 16. Utility code (except TNIC and RPOA) repeated Network conges- tion ## 73 17. Unknown calling network identification Network conges- tion ## 97 18. Bits 7 or 8 of the utility length field octet not set to 0 Network conges- tion ## 101 19. Duplicate TNIC Network conges- tion ## 66 20. The call request packet indi- cated fast select with restriction on response Network conges- tion ## 42 21. Call identifier mismatch Network conges- tion ## 99 22. TNIC mismatch Network conges- tion ## 98 23. Negotiation error in utility parameter value Network conges- tion ## 100 24. NUI utility value invalid/ unsupported or NUI utility required but absent Access barred ## 84 c) Clear request packet Error condition Cause Specific diagnos- tics (see Note 3 of Annex E) 1. Not octet aligned packet (where detection of non–octet alignment is made at packet level if implemented; see § 3) Network conges- tion ## 82 2. Packet too short Network conges- tion ## 38 3. Packet too long Network conges- tion ## 39 4. Address length fields incor- rectly set to non–zero Network conges- tion ## 74 5. Utility length field incorrectly set to non–zero Network conges- tion ## 102 6. Call user data larger than 128 in case of fast select facility (if fast select facility requested) Network conges- tion ## 39 7. Call user data present (if fast select facility not requested) Network conges- tion ## 39 8. Improper cause code from STE (if implemented; see § 4.2.3.1) Network conges- tion ## 81 d) Clear confirmation packet Error condition Cause Specific diagnos- tics (see Note 3 of Annex E) 1. Not octet aligned packet (where detection of non–octet alignment is made at packet level if implemented; see § 3) Network conges- tion ## 82 2. Packet length larger than 3 octets Network conges- tion ## 39 APPENDIX I (to Recommendation X.75) Examples of multilink resetting procedures I.1 Introduction The following examples illustrate application of the multilink reset- ting procedures is the case of: a) MLP reset initiated by a single STE; and b) MLP reset initiated by both STEs simultaneously. I.2 MLP reset initiated by a single STE Figure du point I.2 - T0702240-87 I.3 MLP reset initiated by both STEs simultaneously Figure du point I.3 - T0702250-87