Display TDU information

You can use the DISPLAY TOPO command with the LIST=TDUINFO and SCOPE operands to display VTAM® topology database update (TDU) processing information that could be used to detect a TDU war in the network. A TDU war is the endless exchange of TDUs in contention over the same topology resource, resulting in continuous performance degradation of the APPN network. The topology resources (nodes and TGs) in contention can be identified and, depending on the nature of the problem, the origin of the TDU war may be isolated. If the TDUDIAG start option is set in all network nodes in the network, you can then use the DISPLAY TOPO command with LIST=TDUDIAG to determine which network nodes are updating the resource sequence numbers (RSNs) of the resources in contention. See DISPLAY TOPO in z/OS Communications Server: SNA Operation for additional information about these commands.

Tip: It is not required that every network node in the network append TDU diagnostic information in TDUs (through the TDUDIAG start option). However, it might not be possible to diagnose the problem if one of the network nodes updating the RSN of the resources in contention during a TDU war has TDUDIAG=NEVER specified or does not have support for TDU diagnostic information in TDUs.

Use the following diagnostic steps when a TDU war is suspected:

DISPLAY NET,TOPO,LIST=TDUINFO,SCOPE=ACTIVITY
Use this command to identify the topology resources that are reported in TDUs received and TDUs sent by this node most frequently. In addition, SCOPE=ACTIVITY identifies the topology resources that have had RSNs updated by the host node most frequently, which can indicate whether this node is one of the network nodes involved in a TDU war.
DISPLAY NET,TOPO,LIST=TDUINFO,SCOPE=RECENT
This command displays the topology resources reported in TDUs received and TDUs sent by this node most recently. If the resources obtained in the previous step are also in the output generated by this command, observe the following items:
- Resource sequence numbers (RSNs)
- TDU accepted counts (ACC) and TDU rejected counts (REJ) of the resources reported in TDUs received
- TDU sent counts (SENT) and TDU received counts (REC) of the resources reported in TDUs sent
If these displays show repeated receive and send TDUs for the same resource with one of the following symptoms, you might have detected a TDU war:
- Continuous rejection of TDUs received for a resource (TDU rejected count for the resource is rising), with the RSN in the TDUs rising or unchanged
- Continuous acceptance of TDUs received for a resource (TDU accepted count for the resource is rising), with the RSN in the TDUs rising
Note:
1. There are times that TDUs will flood the network when network nodes propagate topology information to other nodes. For example, when two portions of the same APPN network are connected by CP-CP sessions for the first time, topology information is broadcast in TDUs. The TDU traffic eventually subsides and this is not a TDU war.
2. When TDUs are continuously sent and the RSN updated for the same resource, but TDUs are never received for that resource with higher RSNs, this might not be a TDU war, but a problem with TGs. You can review the system logs to see whether many error messages have been received for TGs that originate in the node that is sending the TDUs.
DISPLAY NET,TOPO,LIST=TDUDIAG
Use this summary command to identify the resources with the most frequent TDU activity (displayed with the DISPLAY NET, TOPO, LIST=TDUINFO,SCOPE=ACTIVITY command) that also contain detailed diagnostic information about RSN updates for that resource.
DISPLAY NET,TOPO,LIST=TDUDIAG with the ORIG, DEST, and TGN operands for a TG or with the ID operand for a node
Use these commands to display the detailed diagnostic information about TDUs describing the resources identified with the previous LIST=TDUDIAG summary command. The detailed TDU diagnostic information identifies the network nodes that are updating the RSN of the resource in contention, thus causing the possible TDU war.

Tip: If the TDUDIAG start option is not set in all network nodes in the network that are involved in a TDU war, this information may not be complete and could be misleading. However, the RSN before the RSN update and the RSN after the RSN update are displayed in each TDU diagnostic record, so it is still possible to determine at least one of the nodes involved.
DISPLAY NET,TOPO,LIST=TDUINFO,CLEAR or DISPLAY NET,TOPO,LIST=TDUDIAG,CLEAR
Use the CLEAR=YES operand to clear all TDU statistics data and all the TDU diagnostic information collected so far. Subsequent displays can be used to show that TDU activities since the last CLEAR command was issued. In a true TDU war, a large amount of TDU traffic is generated within seconds. Thus, the CLEAR operand is useful to confirm whether a TDU war has started.

Tip: When a TDU war is in progress, the RSN value and TDU counter values for a resource can increase rapidly. An RSN value of ******** or TDU counter values of ***** in the output from the DISPLAY NET,TOPO,LIST=TDUINFO command or the DISPLAY NET,TOPO,LIST=TDUDIAG summary command indicates that the values are greater than the available space for those values to be displayed. You can reenter the command with the FORMAT=LONG operand to display these values in a format that includes two lines of output for each resource.

Figure 1 and the sample displays that follow show one example of how a TDU war can occur.

Figure 1. One example of how a TDU war might occur

This figure depicts one example of how a TDU war might occur, which is explained in the text that follows.

In Figure 1,

CP-CP sessions are active between the following nodes:
- NETA.SSCPBA and NETA.SSCP1A (in the upper right corner)
- NETA.SSCPBA and NETA.SSCPAA
- NETA.SSCPBA and NETA.SSCP2A
- NETA.SSCP2A and NETA.SSCP1A (in the upper right corner)
- NETA.SSCP2A and NETA.SSCPAA
No CP-CP sessions are active between NETA.SSCPAA and NETA.SSCP1A (in the lower left corner)

Tip: The default value for the NUM operand is used in the following DISPLAY NET,TOPO,LIST=TDUINFO and DISPLAY NET,TOPO,LIST=TDUDIAG commands to limit the amount of output displayed. You can specify a larger value, up to the maximum value of 50, on the NUM operand if an obvious pattern cannot be detected with the default value when you are diagnosing a possible TDU war.

Initially, from NETA.SSCPBA, the DISPLAY NET,TOPO,LIST=TDUINFO command with the SCOPE operand set to ACTIVITY, or allowed to default, produces the following output:

D NET,TOPO,LIST=TDUINFO,SCOPE=ACTIVITY

IST097I DISPLAY ACCEPTED                                             
IST350I DISPLAY TYPE = TDU INFORMATION                               
IST1780I TOPOLOGY RESOURCES WITH MOST FREQUENT TDU ACTIVITY          
IST2275I TDU INFORMATION SINCE LAST RESET ON 02/11/10 AT 10:48:52    
IST2290I TDUDIAG START OPTION = 1000                                 
IST2276I NO CORRUPTION OF TOPOLOGY CONTROL VECTORS DETECTED          
IST924I -------------------------------------------------------------
IST2286I TDUS RECEIVED:                                              
IST1777I CP NAME           RSN      DESTINATION CP    TGN ACC   REJ  
IST1778I NETA.SSCP2A       4        NETA.SSCPBA       21  2     0    
IST1778I NETA.SSCPAA       10       NETA.SSCPBA       21  2     0    
IST1778I NETA.SSCPBA       4        NETA.SSCP2A       21  0     1    
IST1778I NETA.SSCPBA       4        NETA.SSCPAA       21  0     1    
IST1778I NETA.SSCP2A       4        NETA.SSCPAA       21  1     0    
IST1778I NETA.SSCP2A       4        NETA.SSCP1A       21  1     0    
IST1778I NETA.SSCP2A       2        ***NA***          NA  1     0    
IST1778I NETA.SSCPAA       12       NETA.SSCP2A       21  1     0    
IST1778I NETA.SSCPAA       8        NETA.SSCP1A       21  1     0    
IST1778I NETA.SSCPAA       8        ***NA***          NA  1     0    
IST2301I 10 OF 13 TOPOLOGY RESOURCES DISPLAYED                       
IST924I -------------------------------------------------------------
IST2287I TDUS SENT:                                                  
IST2288I CP NAME           RSN      DESTINATION CP    TGN SENT  REC  
IST1778I NETA.SSCPBA       4        NETA.SSCPAA       21  5     1    
IST1778I NETA.SSCPBA       4        NETA.SSCP2A       21  4     1    
IST1778I NETA.SSCPAA       10       NETA.SSCPBA       21  4     3    
IST1778I NETA.SSCP2A       4        NETA.SSCPBA       21  3     3    
IST1778I NETA.SSCP2A       4        NETA.SSCPAA       21  3     2    
IST1778I NETA.SSCP2A       4        NETA.SSCP1A       21  3     2    
IST1778I NETA.SSCP2A       2        ***NA***          NA  3     2    
IST1778I NETA.SSCPBA       4        NETA.SSCP1A       21  3     2    
IST1778I NETA.SSCPBA       2        ***NA***          NA  3     2    
IST1778I NETA.SSCPAA       12       NETA.SSCP2A       21  3     2    
IST2301I 10 OF 15 TOPOLOGY RESOURCES DISPLAYED                       
IST924I -------------------------------------------------------------
IST2289I RESOURCE SEQUENCE NUMBERS UPDATED BY THIS NODE:             
IST2292I CP NAME           RSN      DESTINATION CP    TGN  UPDATED   
IST2293I NETA.SSCPBA       4        NETA.SSCP2A       21   2         
IST2293I NETA.SSCPBA       4        NETA.SSCPAA       21   2         
IST2293I NETA.SSCPBA       4        NETA.SSCP1A       21   2         
IST2301I 3 OF 3 TOPOLOGY RESOURCES DISPLAYED                         
IST314I END

The DISPLAY NET,TOPO,LIST=TDUINFO command with the SCOPE=RECENT operand specified produces the following output:

D NET,TOPO,LIST=TDUINFO,SCOPE=RECENT  

IST097I DISPLAY ACCEPTED                                             
IST350I DISPLAY TYPE = TDU INFORMATION                               
IST1776I TOPOLOGY RESOURCES WITH MOST RECENT TDU ACTIVITY            
IST2275I TDU INFORMATION SINCE LAST RESET ON 02/11/10 AT 10:48:52    
IST2290I TDUDIAG START OPTION = 1000                                 
IST2276I NO CORRUPTION OF TOPOLOGY CONTROL VECTORS DETECTED          
IST924I -------------------------------------------------------------
IST1779I TDUS RECEIVED BETWEEN 02/11/10 10:49:17 - 02/11/10 10:49:23 
IST1777I CP NAME           RSN      DESTINATION CP    TGN ACC   REJ  
IST1778I NETA.SSCPBA       2        NETA.SSCP2A       21  0     1    
IST1778I NETA.SSCP2A       4        NETA.SSCPBA       21  2     0    
IST1778I NETA.SSCP2A       2        NETA.SSCPBA       21  1     0    
IST1778I NETA.SSCPBA       2        NETA.SSCPAA       21  0     1    
IST1778I NETA.SSCPAA       10       NETA.SSCPBA       21  2     0    
IST1778I NETA.SSCPAA       8        NETA.SSCPBA       21  1     0    
IST1778I NETA.SSCP2A       4        NETA.SSCPAA       21  1     0    
IST1778I NETA.SSCP2A       4        NETA.SSCP1A       21  1     0    
IST1778I NETA.SSCP2A       2        ***NA***          NA  1     0    
IST1778I NETA.SSCPAA       12       NETA.SSCP2A       21  1     0    
IST2301I 10 OF 15 TOPOLOGY RESOURCES DISPLAYED                       
IST924I -------------------------------------------------------------
IST2285I TDUS SENT BETWEEN 02/11/10 10:49:17 - 02/11/10 10:49:23     
IST2288I CP NAME           RSN      DESTINATION CP    TGN SENT  REC  
IST1778I NETA.SSCPBA       4        NETA.SSCP2A       21  4     1    
IST1778I NETA.SSCP2A       4        NETA.SSCPBA       21  3     3    
IST1778I NETA.SSCP2A       2        NETA.SSCPBA       21  2     2    
IST1778I NETA.SSCP2A       4        NETA.SSCPAA       21  3     2    
IST1778I NETA.SSCP2A       4        NETA.SSCP1A       21  3     2    
IST1778I NETA.SSCP2A       2        ***NA***          NA  3     2    
IST1778I NETA.SSCPBA       4        NETA.SSCP2A       21  3     0    
IST1778I NETA.SSCPBA       4        NETA.SSCPAA       21  5     1    
IST1778I NETA.SSCPBA       4        NETA.SSCP1A       21  3     2    
IST1778I NETA.SSCPBA       2        ***NA***          NA  3     2    
IST2301I 10 OF 49 TOPOLOGY RESOURCES DISPLAYED                       
IST314I END

At this point, CP-CP sessions are activated between SSCPAA and a second network node with the CP name of NETA.SSCP1A (pictured in the lower left corner of Figure 1). Because there is an existing network node with this same CP name in the network, this configuration error results in a TDU war. Again from SSCPBA, shortly after CP-CP sessions are activated between SSCPAA and the second NETA.SSCP1A, the DISPLAY NET,TOPO,LIST=TDUINFO,SCOPE=ACTIVITY command produces the following output:

D NET,TOPO,LIST=TDUINFO,SCOPE=ACTIVITY 

IST097I DISPLAY ACCEPTED                                             
IST350I DISPLAY TYPE = TDU INFORMATION                               
IST1780I TOPOLOGY RESOURCES WITH MOST FREQUENT TDU ACTIVITY          
IST2275I TDU INFORMATION SINCE LAST RESET ON 02/11/10 AT 10:48:52    
IST2290I TDUDIAG START OPTION = 1000                                 
IST2276I NO CORRUPTION OF TOPOLOGY CONTROL VECTORS DETECTED          
IST924I -------------------------------------------------------------
IST2286I TDUS RECEIVED:                                              
IST1777I CP NAME           RSN      DESTINATION CP    TGN ACC   REJ  
IST1778I NETA.SSCP1A       3126     NETA.SSCPAA       21  793   4288 
IST1778I NETA.SSCP1A       3128     NETA.SSCPBA       21  793   4260 
IST1778I NETA.SSCP1A       3128     NETA.SSCP2A       21  793   4257 
IST1778I NETA.SSCPAA       16       NETA.SSCP1A       21  5     2    
IST1778I NETA.SSCP2A       4        NETA.SSCPBA       21  2     0    
IST1778I NETA.SSCPAA       10       NETA.SSCPBA       21  2     0    
IST1778I NETA.SSCPBA       4        NETA.SSCP2A       21  0     1    
IST1778I NETA.SSCPBA       4        NETA.SSCPAA       21  0     1    
IST1778I NETA.SSCP2A       4        NETA.SSCPAA       21  1     0    
IST1778I NETA.SSCP2A       4        NETA.SSCP1A       21  1     0    
IST2301I 10 OF 14 TOPOLOGY RESOURCES DISPLAYED                       
IST924I -------------------------------------------------------------
IST2287I TDUS SENT:                                                  
IST2288I CP NAME           RSN      DESTINATION CP    TGN SENT  REC  
IST1778I NETA.SSCP1A       3126     NETA.SSCPAA       21  5257  5119 
IST1778I NETA.SSCP1A       3128     NETA.SSCPBA       21  5231  5101 
IST1778I NETA.SSCP1A       3128     NETA.SSCP2A       21  5228  5098 
IST1778I NETA.SSCPAA       16       NETA.SSCP1A       21  9     11   
IST1778I NETA.SSCPBA       4        NETA.SSCPAA       21  5     1    
IST1778I NETA.SSCPBA       4        NETA.SSCP2A       21  4     1    
IST1778I NETA.SSCPAA       10       NETA.SSCPBA       21  4     3    
IST1778I NETA.SSCP2A       4        NETA.SSCPBA       21  3     3    
IST1778I NETA.SSCP2A       4        NETA.SSCPAA       21  3     2    
IST1778I NETA.SSCP2A       4        NETA.SSCP1A       21  3     2    
IST2301I 10 OF 16 TOPOLOGY RESOURCES DISPLAYED                       
IST924I -------------------------------------------------------------
IST2289I RESOURCE SEQUENCE NUMBERS UPDATED BY THIS NODE:             
IST2292I CP NAME           RSN      DESTINATION CP    TGN  UPDATED   
IST2293I NETA.SSCPBA       4        NETA.SSCP2A       21   2         
IST2293I NETA.SSCPBA       4        NETA.SSCPAA       21   2         
IST2293I NETA.SSCPBA       4        NETA.SSCP1A       21   2         
IST2301I 3 OF 3 TOPOLOGY RESOURCES DISPLAYED                         
IST314I END

The DISPLAY NET,TOPO,LIST=TDUINFO,SCOPE=RECENT command produces the following output:

D NET,TOPO,LIST=TDUINFO,SCOPE=RECENT

IST097I DISPLAY ACCEPTED                                             
IST350I DISPLAY TYPE = TDU INFORMATION                               
IST1776I TOPOLOGY RESOURCES WITH MOST RECENT TDU ACTIVITY            
IST2275I TDU INFORMATION SINCE LAST RESET ON 02/11/10 AT 10:48:52    
IST2290I TDUDIAG START OPTION = 1000                                 
IST2276I NO CORRUPTION OF TOPOLOGY CONTROL VECTORS DETECTED          
IST924I -------------------------------------------------------------
IST1779I TDUS RECEIVED BETWEEN 02/11/10 13:40:14 - 02/11/10 13:40:14 
IST1777I CP NAME           RSN      DESTINATION CP    TGN ACC   REJ  
IST1778I NETA.SSCP1A       3126     NETA.SSCPAA       21  793   4288 
IST1778I NETA.SSCP1A       3128     NETA.SSCP2A       21  793   4257 
IST1778I NETA.SSCP1A       3124     NETA.SSCPAA       21  792   4288 
IST1778I NETA.SSCP1A       3122     NETA.SSCPAA       21  791   4288 
IST1778I NETA.SSCP1A       3128     NETA.SSCPBA       21  793   4260 
IST1778I NETA.SSCP1A       3126     NETA.SSCP2A       21  792   4257 
IST1778I NETA.SSCP1A       3126     NETA.SSCPBA       21  792   4260 
IST1778I NETA.SSCP1A       3124     NETA.SSCPBA       21  791   4260 
IST1778I NETA.SSCP1A       3124     NETA.SSCP2A       21  791   4257 
IST1778I NETA.SSCP1A       3122     NETA.SSCP2A       21  790   4257 
IST2301I 10 OF 50 TOPOLOGY RESOURCES DISPLAYED                       
IST924I -------------------------------------------------------------
IST2285I TDUS SENT BETWEEN 02/11/10 13:40:14 - 02/11/10 13:40:20     
IST2288I CP NAME           RSN      DESTINATION CP    TGN SENT  REC  
IST1778I NETA.SSCP1A       3126     NETA.SSCPAA       21  5257  5119 
IST1778I NETA.SSCP1A       3128     NETA.SSCP2A       21  5228  5098 
IST1778I NETA.SSCP1A       3124     NETA.SSCPAA       21  5256  5118 
IST1778I NETA.SSCP1A       3122     NETA.SSCPAA       21  5255  5117 
IST1778I NETA.SSCP1A       3128     NETA.SSCPBA       21  5231  5101 
IST1778I NETA.SSCP1A       3126     NETA.SSCP2A       21  5227  5097 
IST1778I NETA.SSCP1A       3126     NETA.SSCPBA       21  5230  5100 
IST1778I NETA.SSCP1A       3124     NETA.SSCPBA       21  5229  5099 
IST1778I NETA.SSCP1A       3124     NETA.SSCP2A       21  5226  5096 
IST1778I NETA.SSCP1A       3122     NETA.SSCP2A       21  5225  5095 
IST2301I 10 OF 50 TOPOLOGY RESOURCES DISPLAYED                       
IST314I END

These last two commands display the following symptoms of a TDU war:

There are many inbound and outbound TDUs describing the same resources.
The resource sequence number (RSN) and TDU rejection count (REJ) in message IST1778I for the following resources increase continuously:
- TG oriented from NETA.SSCP1A to NETA.SSCPBA with TG number 21
- TG oriented from NETA.SSCP1A to NETA.SSCP2A with TG number 21
- TG oriented from NETA.SSCP1A to NETA.SSCPAA with TG number 21
Because NETA.SSCPBA continuously receives TDUs about the above three resources, they become the most active resources (in terms of TDUs received) reported by DISPLAY NET,TOPO,LIST=TDUINFO,SCOPE=ACTIVITY command.

If the TDUDIAG start option is set in one or more of the network nodes involved in the TDU war, additional TDU diagnostic information will be collected about the network nodes that are updating the RSNs of these resources. The DISPLAY NET,TOPO,LIST=TDUDIAG command produces the following output:

D NET,TOPO,LIST=TDUDIAG

IST097I DISPLAY ACCEPTED                                             
IST350I DISPLAY TYPE = TDU DIAGNOSTICS                               
IST2274I TDU DIAGNOSTIC SUMMARY:                                     
IST1780I TOPOLOGY RESOURCES WITH MOST FREQUENT TDU ACTIVITY          
IST2308I   THAT HAVE SAVED TDUDIAG RSN UPDATES                       
IST2275I TDU INFORMATION SINCE LAST RESET ON 02/11/10 AT 13:11:32    
IST2290I TDUDIAG START OPTION = 1000                                 
IST2276I NO CORRUPTION OF TOPOLOGY CONTROL VECTORS DETECTED          
IST924I -------------------------------------------------------------
IST2286I TDUS RECEIVED:                                              
IST1777I CP NAME           RSN      DESTINATION CP    TGN ACC   REJ  
IST1778I NETA.SSCP1A       3126     NETA.SSCPAA       21  793   4288 
IST1778I NETA.SSCP1A       3128     NETA.SSCP2A       21  793   4257 
IST1778I NETA.SSCP1A       3128     NETA.SSCPBA       21  793   4260 
IST2301I 3 OF 3 TOPOLOGY RESOURCES DISPLAYED                         
IST924I -------------------------------------------------------------
IST2287I TDUS SENT:                                                  
IST2288I CP NAME           RSN      DESTINATION CP    TGN SENT  REC  
IST1778I NETA.SSCP1A       3126     NETA.SSCPAA       21  5257  5119 
IST1778I NETA.SSCP1A       3128     NETA.SSCP2A       21  5228  5098 
IST1778I NETA.SSCP1A       3128     NETA.SSCPBA       21  5231  5101 
IST2301I 3 OF 3 TOPOLOGY RESOURCES DISPLAYED                         
IST924I -------------------------------------------------------------
IST2289I RESOURCE SEQUENCE NUMBERS UPDATED BY THIS NODE:             
IST2301I 0 OF 0 TOPOLOGY RESOURCES DISPLAYED                         
IST314I END

Additional detailed TDU diagnostic information about the network nodes that are updating the RSNs of each TG can be displayed with LIST=TDUDIAG. The DISPLAY NET,TOPO,LIST=TDUDIAG,ORIG=SSCP1A,DEST=SSCPBA,TGN=21 command produces the following output:

D NET,TOPO,LIST=TDUDIAG,ORIG=SSCP1A,DEST=SSCPBA,TGN=21

IST097I DISPLAY ACCEPTED                                             
IST350I DISPLAY TYPE = TDU DIAGNOSTICS                               
IST2311I TDU DIAGNOSTIC INFORMATION FOR TG: TGN = 21                 
IST2256I ORIG = NETA.SSCP1A - DEST = NETA.SSPCBA                     
IST2312I CURRENT RSN = 3128 - HEX RSN = 00000C38                     
IST924I -------------------------------------------------------------
IST2275I TDU INFORMATION SINCE LAST RESET ON 02/11/10 AT 10:48:52    
IST1769I LAST TDU RECEIVED - 02/11/10 13:40:14 FROM NETA.SSCP1A      
IST2281I LAST TDU SENT - 02/11/10 13:40:20                           
IST2282I TDU COUNTS:                                                 
IST2352I   SENT     = 3890         RECEIVED = 5101                   
IST2353I   ACCEPTED = 793          REJECTED = 4260                   
IST2354I   IGNORED  = 48                                             
IST2313I RSN UPDATE COUNT = 4260                                     
IST924I -------------------------------------------------------------
IST2294I TDUDIAG RSN UPDATES:                                        
IST2295I                    TIME      HEX RSN   HEX RSN              
IST2296I CP NAME            UPDATED   BEFORE    AFTER     REASON     
IST2297I NETA.SSCP1A        13:40:20  00000C36  00000C38  TDU GREATER
IST2300I   RECEIVED FROM: NETA.SSCP1A                                
IST2297I NETA.SSCP1A        13:40:20  00000C34  00000C36  TDU GREATER
IST2300I   RECEIVED FROM: NETA.SSCP2A                                
IST2297I NETA.SSCP1A        13:40:19  00000C32  00000C34  TDU GREATER
IST2300I   RECEIVED FROM: NETA.SSCP1A                                
IST2297I NETA.SSCP1A        13:40:19  00000C30  00000C32  TDU GREATER
IST2300I   RECEIVED FROM: NETA.SSCPAA                                
IST2297I NETA.SSCP1A        13:40:19  00000C2E  00000C30  TDU GREATER
IST2300I   RECEIVED FROM: NETA.SSCP1A                                
IST2297I NETA.SSCP1A        13:40:19  00000C2C  00000C2E  TDU GREATER
IST2300I   RECEIVED FROM: NETA.SSCPAA                                
IST2297I NETA.SSCP1A        13:40:19  00000C2A  00000C2C  TDU GREATER
IST2300I   RECEIVED FROM: NETA.SSCP1A                                
IST2297I NETA.SSCP1A        13:40:19  00000C28  00000C2A  TDU GREATER
IST2300I   RECEIVED FROM: NETA.SSCP2A                                
IST2297I NETA.SSCP1A        13:40:19  00000C26  00000C28  TDU GREATER
IST2300I   RECEIVED FROM: NETA.SSCP1A                                
IST2297I NETA.SSCP1A        13:40:18  00000C24  00000C26  TDU GREATER
IST2300I   RECEIVED FROM: NETA.SSCPAA                                
IST2314I 10 OF 50 RSN UPDATES DISPLAYED                              
IST314I END

Because the previous command was entered on SSCPBA, which is not the origin (owner) of the TG, all of the RSN updates are inbound to SSCPBA. Therefore, you cannot tell if the RSN for the resource is being updated by one network node with a CP name of NETA.SSCP1A, or two. When the RSN increased by two and all of the TDUDIAG RSN updates display the same CP name in message IST2297I, it is usually an indication of two network nodes with the same CP name. To determine whether this is the case, you can enter the same command on the NETA.SSCP1A known to you, which produces the following output:

D NET,TOPO,LIST=TDUDIAG,ORIG=SSCP1A,DEST=SSCPBA,TGN=21

IST097I DISPLAY ACCEPTED                                             
IST350I DISPLAY TYPE = TDU DIAGNOSTICS                               
IST2311I TDU DIAGNOSTIC INFORMATION FOR TG: TGN = 21                 
IST2256I ORIG = NETA.SSCP1A - DEST = NETA.SSCPBA                     
IST2312I CURRENT RSN = 3128 - HEX RSN = 00000C38                     
IST2355I TDUDIAG THRESHOLD REACHED ON 02/11/10 AT 13.39.00           
IST924I -------------------------------------------------------------
IST2275I TDU INFORMATION SINCE LAST RESET ON 02/11/10 AT 10:48:52    
IST1769I LAST TDU RECEIVED - 02/11/10 13:40:14 FROM NETA.SSCP1A      
IST2281I LAST TDU SENT - 02/11/10 13:40:20                           
IST2282I TDU COUNTS:                                                 
IST2352I   SENT     = 793          RECEIVED = 793                    
IST2353I   ACCEPTED = 0            REJECTED = 793                    
IST2354I   IGNORED  = 0                                              
IST2313I RSN UPDATE COUNT = 793                                      
IST924I -------------------------------------------------------------
IST2294I TDUDIAG RSN UPDATES:                                        
IST2295I                    TIME      HEX RSN   HEX RSN              
IST2296I CP NAME            UPDATED   BEFORE    AFTER     REASON     
IST2297I NETA.SSCP1A        13:40:20  00000C36  00000C38  TDU GREATER
IST2297I NETA.SSCP1A        13:40:20  00000C34  00000C36  TDU GREATER
IST2300I   RECEIVED FROM: NETA.SSCP2A                                
IST2297I NETA.SSCP1A        13:40:19  00000C32  00000C34  TDU GREATER
IST2297I NETA.SSCP1A        13:40:19  00000C30  00000C32  TDU GREATER
IST2300I   RECEIVED FROM: NETA.SSCPBA                                
IST2297I NETA.SSCP1A        13:40:19  00000C2E  00000C30  TDU GREATER
IST2297I NETA.SSCP1A        13:40:19  00000C2C  00000C2E  TDU GREATER
IST2300I   RECEIVED FROM: NETA.SSCPBA                                
IST2297I NETA.SSCP1A        13:40:19  00000C2A  00000C2C  TDU GREATER
IST2297I NETA.SSCP1A        13:40:19  00000C28  00000C2A  TDU GREATER
IST2300I   RECEIVED FROM: NETA.SSCP2A                                
IST2297I NETA.SSCP1A        13:40:19  00000C26  00000C28  TDU GREATER
IST2297I NETA.SSCP1A        13:40:18  00000C24  00000C26  TDU GREATER
IST2300I   RECEIVED FROM: NETA.SSCPBA                                
IST2314I 10 OF 50 RSN UPDATES DISPLAYED                              
IST314I END

Messages IST2297I and IST2300I are displayed for inbound TDUs. For outbound TDUs, only message IST2297I is displayed. From this display, you can see that TDUs with RSN updates are both inbound to and outbound from this node. If the TDU is inbound, the RSN was not updated by this node. If the TDU is outbound, the RSN was updated by this node. This pattern indicates that there is another network node with a CP name of NETA.SSCP1A in the network.