software) on this connection at any time. This field has the range 1 < abl < 7. You can access this field with the reserved symbol CONABL, as described in section 47
Upline block limit. This parameter specifies the maximum number (1 < upblim < 31) of blocks that the NPU can have outstanding (unacknowledged) to the calling holt. This~parameter is meaningful only for X.25 connections.
Upline block size. This parameter specifies the maximum number (1 £ upsize < 2000) of bytes that the NPU can send to the calling host in a block. This parameter is only used for X.25
links.
Send window size. (Applicable on Public Data Network A-A connections only. Ignored on other A-A connections.)
Send data packet length. (Applicable on Public Data Network A-A connections only. Ignored on other A-A connections.)
Number of facility groups. (Applicable to Public Data Network A-A connections only.) Length of call user data (in octets).
Facility codes length, within the CM word. (Applicable to Public Data Network A-A connections only.)
Facility codes. (Applicable to Public Data Network A-A connections only.)
Protocol ID. (Applicable to Public Data Network A-A connections only.) 1-8 hexadecimal digits, left justified, zero filled. If CUDL t 0, then only the first 6 hexadecimal digits will be passed on to the PDN, the last two hexadecimal digits will be zeroed.
Figure 3-12. Request-Application-Connection (CON/ACRQ/R) Supervisory Message Format (Sheet 2 of 3)
60499500 S 3-19*
udata Call user data. If the destination host is a NOS system running network products, the first 12t octets must be of the form SSS DD AAAAAAA, where:
SSS D D
AAAAAAAis the 3 ASCII character equivalent of the SNODE (sendng node number) value, right justified, zero-character filled.
is the 2 ASCII character string equivalent of the DHOST (destination host number) value, right justified, zero-character filled.
is the 7 ASCII character string equivalent of the called applica- tion's application name, left justified, blank-character filled.
The remainder of the UDATA filled (0-112 octets) will be passed to the called application as user data.
At any rate, the called host/application if accessed through a public data network must be able to support the Fast Select Facility, if more than 12 octets of information are specified.
Note: For applications accessing foreign hosts through a public data network the 4 octets of the PRID field and the (up to) 124 octets of the UDATA field are combined into the (up to) 128 octets of used data as defined by the CCITT recommendation for X.25 networks.
TAn octet is 8 bits of information.
Figure 3-12. Request-Application-Connection (CON/ACRQ/R) Supervisory Message Format (Sheet 3 of 3)
ta
acrq
ta
59 51 49 43 35 17
con
acrqre abn
reservednamel name2
Symbolic address of the application program's text area receiving this asynchronous super visory message.
Primary function code 63^0. You can access this field with the reserved symbol PFC, as described in section 4. Its value is defined as the value of reserved symbol CON.
Secondary function code 2. You can access this field with the reserved symbol SFC, as described in section 4. Its value is defined as the value of the reserved symbol ACRQ.
Reason code, specifying the cause for rejecting the connection request. The field is
actually made up of two 4 bit subfields, rc1 and rc2. The rc1 field comprises bits 40-43 and the rc2 field comprises bits 36-39.
The rc2 field is used so that the application can determine what action to take when it receives a CON/ACRQ/A message and it provides some general information about the source of the trouble. This field can have the following values:
1 = Critical error in call request detected by source host (only LID/PID/NDL configuration changes or application code changes would solve the problem).
2 = Critical error in call request detected by destination host.
3 = Source host temporarily cannot make the connection (resources are currently not available, but they might become available without operator intervention).
4 = Destination host temporarily cannot make the connection.
Figure 3-13. Application-Connection-Reject (CON/ACRQ/A) Supervisory Message Format (Sheet 1 of 4)
• 3-20 60499500 S
4 0 ^ \
5 = Source host cannot make the connection for an indefinite period of time (resources can be made available by operator intervention such as enabling a LID/PID, network element, or bringing up a system or subsystem).
6 = Destination host cannot make the connection for an indefinite period of time.
Thus if rc2 = 1 or 2, the application would not try establishing the connection again, it would notify the user and/or operator that the connection is not possible.
If rc2 =3 or 4 then the application can retry the CON/ACRQ message after a shorter period of time, and if rc2 = 5 or 6 then it will retry the CON/ACRQ after a somewhat longer period of time.
The rd field is used in combination with the rc2 field to uniquely identify the exact source of the trouble, so that the user/operator can take the appropriate action to fix the
problem. The full 8 bit reason code field can therefore have the following values:
2 = Network error detected by destination host. Contact system analyst at destination nost.
4 = Connection number conflict between source and destination host. Retry connection request.
17 = Illegal LID/PID combination was specified. Correct LID/PID in OUTCALL block.
18 = Called application is not defined in system record (CONTNAP) at destination host.
Contact system analyst.
19 = Network Validation Facility (NVF) temporarily cannot process connection request.
Retry later.
20 = Called application cannot accept any more connections and another copy of the application cannot be started up. Retry later.
22 = Called application is not running and cannot be started automatically. Contact system analyst to start up called application.
33 = Calling application is not privileged, i.e., it is not allowed to issue OUTCALLS.
Contact system analyst to make the application a privileged application in the LCF.
34 = OUTCALL block has facility parameters greater than 4 octets in length. Correct the OUTCALL block.
35 = NAM temporarily cannot complete the connection request because the (logical) link to the destination host is not available. Retry Later.
37 = Specified PID is valid but is currently not available. Retry later.
38 = Called application is disabled. Contact system analyst to enable the application.
49 = Application specified its own OUTCALL parameters but there was no corresponding OUTCALL entry in the LCF for the same PID. Correct the OUTCALL parameters in the CON/ACRQ/A.
50 = OUTCALL block had user parameters greater than 124 octets in length. Correct the OUTCALL block.
53 = Source host is not allowing any new connections because it is in idle or disabled state. Retry Later.
54 = Destination host is not allowing any new connections because it is in idle or disabled state. Retry later.
65 = Application specified its own OUTCALL parameters but there was no matching OUTCALL entry in the LCF. Correct the OUTCALL parameters in the CON/ACRQ/R.
66 = Destination host could not find a matching INCALL block in its LCF. Correct the OUTCALL block.
81 = Calling application has already reached its maximum number of allowed connections.
Retry later.
Figure 3-13. Application-Connection-Reject (CON/ACRQ/A) Supervisory Message Format (Sheet 2 of 4)
6 0 4 9 9 5 0 0 S 3 _ 2 1 #
82 = Name of application specified in CON/ACRQ is invalid. Correct the application.
97 = Retry limit has been reached for calling application. No more application to application connection requests (CON/ACRQ/R) should be issued. The reason codes for the previous CON/ACRQ/A should be analyzed.
98 = Destination host could not find a matching INCALL block in the LCF with a matching facility code. Correct the facility code in the OUTCALL block.
100 = Network Validation Facility (NVF) in the destination host has not netted on yet.
Retry Later.
114 = Application requested Fast select but matching INCALL block in LCF at the
destination host does not have Fast select specified. Correct the OUTCALL block to not select Fast select.
129 = No X25 TIP in NPU at source host. Contact system analyst to rebuild CCP with X25 TIP.
130 = Error in incoming call packet header. Contact system analyst about possible PSN problem.
132 = Unknown packet from remote, i.e., the packet received is not a call accepted or call connected. This is assumed to be caused by a call collision. Retry later.
133 = No available logical channel at source host, i.e., active number of SVCs are greater than enabled SVCs. Contact the system analyst about enabling additional SVCs.
134 = No available logical channel at destination host, i.e., active number of SVCs are greater than enabled SVCs. Contact the system analyst at the destination host to enable some more SVCs.
145 = X25 subtip not available in NPU at source host. Contact system analyst for rebuilding CCP.
146 = X25 subtip not available in NPU at destination host. Contact system analyst at destination site for rebuilding CCP.
147 = NPU at source host temporarily has no buffer space to support the connection.
Retry later.
148 = NPU at destination host temporarily has no buffer space to support the connection.
Retry later.
161 = Problem detected by X25 network at local host. PSN CCC=13. Local procedure error. Clear problem with PSN administration.
162 = Remote host not known. Correct DD field in UDATA in OUTCALL entry in the LCF or in the CON/ACRQ/R message.
163 = No connection available, i.e., all SVCs (outside lines) have been used. Retry l a t e r.
164 = Problem detected by X25 network at destination host. PSN CCC=1. Number at destination host is busy. Retry later.
165 = X25 line is down at source host. Retry later.
166 = X25 line is down at destination host. Retry later.
178 = Unknown subtip connection; i.e., the PRID field is not CO (PAD) or C1 (A-A). Fix the PRID field in the OUTCALL entry in the LCF or in the CON/ACRQ/R message.
180 = Problem detected by X25 network. PSN CCC=5. PSN congestion. Retry later.
182 = CCP cannot complete the connection because the (logical) link at the destination host is not up (enabled). The system analyst should be contacted to enable the
logical link.
Figure 3-13. Application-Connection-Reject (CON/ACRQ/A) Supervisory Message Format (Sheet 3 of 4)
• 3-22 60499500 S
dpls
fa en
cudl
f a c l
fac
p r i d
j0^\.
udata
Send data packet length, specifying the maximum number of data octets (8-bit bytes) an X 25 packet can contain. This parameter applies only to X.25 network application-to-application connections and is ignored on other application-to-application connections. The dpls
£a,£aT?.ter 1s an aPP!:ication supplied OUTCALL parameter. An application can supply its own OUTCALL parameters if it is a privileged application (SSJ= entry point, or a non-zero SSID) This parameter does not need to appear in the OUTCALL statement in the LCF. You can access"
this field with the reserved symbol CONDPLS, as described in section 4.
Number of facility groups. This parameter applies only to X.25 network
a P P ^ t ^ - t o - a p p l i c a t i o n c o n n e c t i ° n s . T h e f a c n p a r a m e t e r i s a n a p p l i c a t i o n s u p p l i e d OUTCALL parameter. An application can supply its own OUTCALL parameters if it is a privileged application (SSJ= entry point, or a non-zero SSID). In this case, the facn parameter does not need to appear in the OUTCALL statement in the LCF. You can access this field with the reserved symbol CONFACN, as described in section 4.
Length of user data (in octets). The cudl parameter is an application supplied OUTCALL parameter. An application can supply its own OUTCALL parameters if it is a privileged
•PP uCa!nS!!,MSSJ= entry P<?int' or a non-2ero SSID>- This parameter does not need to appear l S ,0 U T C AL s tatem ent i n the LC F. You c an ac c es s t hi s fi el d w i th th e re ser v ed symbol CONAUDL, as described in section 4.
F a c i l i ty co de l eng th , s pec i fyi ng t he l ength of a fac i l i t y fi el d w i th i n t he c ent ra l memory word. This parameter applies only to X.25 network application-to-application connections.
The facl parameter is an application supplied OUTCALL parameter. An application can supply s c ™ ? ™ ^ T C A L L P ^ ^ t e r s i f i t i s a p r i v i l e g e d a p p l i c a t i o n ( S S J = e n t r y p o i n t , o r a n o n - z e r o SSID). This parameter does not need to appear in the OUTCALL statement in the LCF.
F a c i l i t y c o d e , s p e c i f y i n g t h e f a c i l i t y c o d e f o r a f a c i l i t y fi e l d . T h i s p a r a m e t e r a p p l i e s only to X.25 network application-to-application connections. The fac parameter is an
application supplied OUTCALL parameter. An application can supply its own OUTCALL parameters if it is a privileged application (SSJ= entry point, or a non-zero SSID). This parameter does not need to appear in the OUTCALL statement in the LCF.
The protocol identification. This parameter tells the PSN or remote node of a direct X.25 link how call user data is to be used. This parameter applies only to X.25 network
a p p l i c a t i o n - t o - a p p l i c a t i o n c o n n e c t i o n s a n d m u s t b e 1 t o 8 h e x a d e c i m a l d i g i t s , l e f t - j u s t i fi e d , and zero-filled. If CUDL r 0, only the first 6 hexadecimal digits are passed to the X.25 network, and the last two hexadecimal digits are zeroed. The prid parameter is an
application supplied OUTCALL parameter. An application can supply its own OUTCALL parameters if it is a privileged application (SSJ= entry point, or a non-zero SSID). This parameter does not need to appear in the OUTCALL statement in the LCF.
Call user data. If the destination host is a NOS system running network products, the first 12T octets must be of the form sss dd aaaaaaa, where:
sss is the 3 character ASCII equivalent of the SNODE (sendng node number) value, r i g h t - j u s t i fi e d , z e r o fi l l e d .
dd is the 2 character ASCII equivalent of the DHOST (destination host number) v a l u e , r i g h t - j u s t i fi e d , z e r o fi l l e d .
a a a a a a a i s t h e 7 c h a r a c t e r A S C I I e q u i v a l e n t o f t h e c a l l e d a p p l i c a t i o n ' s a p p l i c a t i o n n a m e , l e f t - j u s t i fi e d , b l a n k fi l l e d .
The remainder of the udata field (0-112 octets) is passed to the called application as user d a t a .
The called host/application (if accessed through an X.25 network) must be able to support the Fast Select Facility, if more than 12 octets of information are specified.
Note: For applications accessing foreign hosts through an X.25 network, the 4 octets of the PRID field and the (up to) 124 octets of the UDATA field are combined into the (up to) 128 octets of used data as defined by the CCITT recommendation for X.25 networks.
You cannot access this field with NFETCH.
tAn octet is 8 bits of informati<
Figure 3-12. Request-Application-Connection (CON/ACRQ/R) Supervisory Message Format (Sheet 3 of 3)
60499500 W 3-23
59 5 1 4 9 43 35 17
t a acrq abn reserved
namel name2
t a
a c r q
Symbolic address of the application program's text area receiving this asynchronous super visory message.
Primary function code 63<j0. You can access this field with the reserved symbol PFC, as described in section 4. Its value is defined as the value of reserved symbol CON.
Secondary function code 2. You can access this field with the reserved symbol SFC, as described in section 4. Its value is defined as the value of the reserved symbol ACRQ.
Reason code, specifying the cause for rejecting the connection request. The field is actually made up of two 4 bit subfields, rd and rc2. The rc1 field comprises bits 40 through 43 and the rc2 field comprises bits 36 through 39.
The rc2 field is used so that the application can determine what action to take when it receives a CON/ACRQ/A message and it provides some general information about the source of the trouble. This field can have the following values:
1 = Critical error in call request detected by source host (only LID/PID/NDL configuration changes or application code changes can solve the problem).
2 = Critical error in call request detected by destination host.
3 = Source host temporarily cannot make the connection (resources are currently not available, but they might become available without operator intervention).
4 = Destination host temporarily cannot make the connection.
5 = Source host cannot make the connection for an indefinite period of time (resources can be made available by operator intervention such as enabling a LID/PID, network element, or bringing up a system or subsystem).
6 = Destination host cannot make the connection for an indefinite period of time.
Thus if rc2 = 1 or 2, the application should not try establishing the connection again; it should notify the user and/or host operator that the connection is not possible.
If rc2 = 3 or 4, then the application can retry the CON/ACRQ message after a short time, and if rc2 = 5 or 6, then it can retry the CON/ACRQ after a longer time.
The rd field is used in combination with the rc2 field to uniquely identify the exact source of the trouble, so that the user/operator can take the appropriate action to fix the
problem. The full 8-bit reason code field can therefore have the following values:
2 = Network error detected by destination host. Contact system analyst at destination h o s t .
4 = Connection number conflict between source and destination host. Retry connection request.
17 = Invalid LID/PID combination was specified. Correct LID/PID in OUTCALL block.
18 = Called application is not defined in system record (CONTNAP) at destination host.
Contact system analyst.
19 = Network Validation Facility (NVF) temporarily cannot process connection request.
R e t r y l a t e r.
20 = Called application cannot accept any more connections and another copy of the application cannot be started up. Retry later.
/ " ^ H
Figure 3-13. Application-Connection-Reject (CON/ACRQ/A) Supervisory Message Format (Sheet 1 of 4)
3-24 60499500 W
ypfey
Neither application program can send or receive any supervisory messages or data blocks on a connection u n t i l c o n n e c t i o n i n i t i a l i z a t i o n p r o c e s s i n g h a s b e e n completed.
I f e i t h e r p r o g r a m c a n n o t c o m p l e t e o r s e r v i c e t h e l o g i c a l c o n n e c t i o n , I t c a n r e j e c t t h e c o n n e c t i o n r e q u e s t b y i s s u i n g t h e a s y n c h r o n o u s c o n n e c t i o n -r e j e c t e d m e s s a g e d e s c -r i b e d i n fi g u -r e 3 - 5 . W h e n t h i s o c c u r s , t h e o t h e r a p p l i c a t i o n p r o g r a m m u s t exchange the connection-broken, end-connection, and connection-ended asynchronous supervisory messages w i t h t h e n e t w o r k s o f t w a r e . N o f u r t h e r a c t i o n i s
required by the rejecting application program.
I f e i t h e r a p p l i c a t i o n p r o g r a m d o e s n o t f o l l o w t h e message sequences shown in figure 3-15, a logical-error asynchronous supervisory message is issued.
T h i s m e s s a g e i s d i s c u s s e d a t t h e e n d o f t h i s s e c t i o n .
A logical connection established between two appli cation programs does not necessarily have the same application connection number for both applications.
Th e netw ork so ftw a re assi gns th e a ppl i cati on con nection number to each end of the logical connection i n d e p e n d e n t l y. T h e a p p l i c a t i o n c o n n e c t i o n n u m b e r is unique within all connections of each application program; for example, the same logical connection c a n h a v e a n a c n p a r a m e t e r o f 2 f o r a p p l i c a t i o n program A (which accepted one previous connection) but an acn parameter of 4 for application program B
(which accepted three previous connections).
Privileged applications can specify OUTCALL param e t e r s i n o p t i o n a l w o r d s 2 - 1 0 o f t h e C O N / A C R Q / R sequence. This allows the aplications to have more c o n t r o l o v e r a n o u t g o i n g c a l l r e q u e s t . T h e a p p l i cation specifies a complete OUTCALL block' except for the SNODE, DNODE, PORT, and DTE address param eters. NAM obtains these parameter values from the first OUTCALL statement defined in the LCF that has a matching NAME2 (PID).
A p p l i c a t i o n NAM Message
FC/INACT/R The timer for the logical connection is reset to z e r o .
A p p l i c a t i o n 1 N A M A p p l i c a t i o n 2 M e s s a g e
~ ▶ F C / I N A C T / R
The timer for the logical connection is reset to z e r o .
Figure 3-15. Connection Monitoring Message Sequences