Internet Standards/CD2.mdf/ccitt/1992/x/x75_a.asc

Text File | 1993-08-17 | 37KB | 3,828 lines

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 timeûouts, if any,
in the packet layer.

A.2    Symbol definition of the state diagrams

Figure Aû1/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:

û    The figures are arranged in order of priority with Figure Aû2/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.

û    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 Cû1/X.75 to Cû5/X.75 and Dû1/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 Bû1/X.75 - CCITT 19180



Figure Bû2/X.75 - CCITT 19190 et CCITT 19200



Figure Bû3/X.75 - CCITT 19180



Figure Bû4/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 û Actions are specified for STEûY only. STEûX should follow the
same procedure.

TABLE Cû1/X.75

Action taken by STEûY on receipt of packets



State of the interface as perceived
by STEûY

Packet received by STEûY

 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 Cû2/X.75)

 DISCARD    STEûY discards the received packet and takes no subsequent
action.

Note û 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 Cû2/X.75

Action taken by STEûY on receipt of packets in a given state: restart



State of the interface as perceived by
STEûY

 Packet
layer

 STEûX
restart

 STEûY
restart

Packet received by STEûY

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 setûup or clear when both logical
channel number and logical channel
group number are not all 0s

 (See
Table
Cû3/
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
º 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 º 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 STEûY follows the normal procedures as
defined in º 3 of the text (see Note 2).

DISCARD    STEûY discards the received packet and takes no subsequent
action.

ERROR        STEûY discards the received packet and indicates restarting with
ônetwork congestionö cause and decimal diagnostic value ##n.

Note 1 û If STEûY 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 û 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 nonûoctet 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 nonûoctet alignment is
made at packet layer) is not octet aligned; diagnostic values ##39,
##38 and ##82 respectively, are used.

TABLE Cû3/X.75

Action taken by STEûY 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 STEûY

 Packet layer ready r1





Packet received by
STEûY

Read
y


p1

STEûX
call
request
p2

STEûY
call
request
p3

Data
transf
er

p4

STEûX
clear
request
p6

STEûY
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 2╣ 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 º 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 STEûY follows the normal procedures as
defined in º 3 of the text. However, if an error condition specified in Annex
F occurs, STEûY discards the received packet and indicates clearing with
the cause and diagnostic codes specified in Annex F.

DISCARD    STEûY discards the received packet and takes no subsequent
action.

ERROR        STEûY discards the received packet and indicates clearing with
ônetwork congestionö cause and decimal diagnostic value ## n.

Note 1 û If STEûY 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 û The ERROR (p7) procedure is invoked if STEûY receives a call
connected packet in response to a call request packet from STEûY request-
ing the fast select facility with restriction on response.

TABLE Cû4/X.75

Action taken by STEûY on receipt of packets specifying an assigned logical
channel in a given state: reset



State of the inter-
faceas perceived
by STEûY

 Data transfer p4



Packet received
by STEûY

Flow control
ready d1

STEûX reset
request d2

STEûY 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 Cû5/
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 ╣ 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 º 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 STEûY follows the normal procedures as
defined in º 3 of the text (see Note 2).

DISCARD    STEûY discards the received packet and takes no subsequent
action.

ERROR        STEûY discards the received packet and indicates resetting with
ônetwork congestionö cause and decimal diagnostic value ## n.

Note 1 û If STEûY 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 û 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 nonûoctet alignment is made at packet
layer) is not octet aligned; diagnostic values ## 39, ## 38 and ## 82 respec-
tively are used.

TABLE Cû5/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 STEû
Y

 Flow control ready d1



Packet received
by STEûY

Not inter-
rupted i1

STEûX
interrupt
request i2

STEûY
interrupt
request i3

STEûX 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 STEûY follows the normal procedures as
defined in º 3 of the text (see Note 2).

DISCARD    STEûY discards the received packet and takes no subsequent
action.

ERROR        STEûY discards the received packet and indicates reset with ônet-
work congestionö cause and decimal diagnostic value ## n.

Note 1 û According to º 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 û 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 nonûoctet alignment is made at packet
layer) is not octet aligned; diagnostic values ## 39, ## 38 and ## 82 respec-
tively are used.

Note 3 û According to º 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 timeûouts 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 timeûout in the STE X/Y will initiate the actions sum-
marized in Tables Dû1/X.75 and Dû2/X.75. Therefore, this must be taken
into account in the STE design.

TABLE Dû1/X.75

STE X/Y timeûouts (first time)



Time
-out
num
ber


Time
ûout
value

Stat
e of
the
logi
cal
cha
nnel


Started
when

 Normally
terminated
when

 Actions to be taken the first
time the timeûout 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 timeû
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 timeû
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 timeû
out T33

TABLE Dû2/X.75

STE X/Y timeûouts (second time)



Timeûout num-
ber

 Actions to be taken the second time the timeûout
expires



Toward STE Y/X

 Toward network

 T30

 STE X/Y enters the r1
state Note û 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 Eû1/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 nonûzero in bits
1û4, 9û16

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 Eû1/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 setûup 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

    Nonûzero address length

0

 1

 0

 0

 1

 0

 1

 0

  74

    Nonûzero 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 CCITTûspecified 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 nonûaligned

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

 Interûnetwork call setûup 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

    Nonûzero 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 Eû1/X.75 (continued)



Bits



Diagnostics

 8

 7

 6

 5

 4

 3

 2

 1

Deci
mal

 Interûnetwork problem

 0

 1

 1

 1

 0

 0

 0

 0

 112

    Remote network problem

0

 1

 1

 1

 0

 0

 0

 1

 113

    Interûnetwork protocol prob-
lem

0

 1

 1

 1

 0

 0

 1

 0

 114

    Interûnetwork link out of
order

0

 1

 1

 1

 0

 0

 1

 1

 115

    Interûnetwork 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

    Interûnetwork 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 û Not all diagnostic codes need apply to a specific network, but
those used are coded as in the table.

Note 2 û A given diagnostic need not apply to all packet types (i.e. reset
request, clear request and restart request packets).

Note 3 û 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 û Only generated at a user interface (see Recommendation X.25).

Note 5 û When associated with the cause ôNetwork congestionö, 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 û When associated with the cause ôNetwork congestionö, 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 û When associated with the cause ôNetwork congestionö, 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 û When the associated cause is ôNetwork congestionö, 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 ºº4.2.3.2, 4.4.3.2 or 4.5.1.2 as appropriate,
before passing them to another network or across a user interface.

Note 9 û When the associated cause is ôNetwork congestionö, diagnostic
codes in the range 1 to 111 will be altered by the receiving network, as
described in ºº 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 nonûoctet
alignment is made at packet level
if implemented; see º 3)

Network conges-
tion

 ## 82

  2.    Address contains a nonûBCD
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
STEûX/Y interface

Network conges-
tion

 ## 113

 34.    X.75 protocol error detected
other than at the local STEûX/Y
interface

Network conges-
tion

 ## 114

 35.    No interûAdministration ser-
vice agreement is recorded for
calls from the calling network to
the called network

Access barred

 ## 119

 36.    No interûAdministration 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 interûAdministration 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 û 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 nonûoctet
alignment is made at packet level
if implemented; see º 3)

Network conges-
tion

 ## 82

  2.    Address contains a nonûBCD
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 nonûoctet
alignment is made at packet level
if implemented; see º 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 nonûzero

Network conges-
tion

 ## 74

  5.     Utility length field incorrectly
set to nonûzero

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 º 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 nonûoctet
alignment is made at packet level
if implemented; see º 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