Subject: Unknown Network Control RU

From: "jim (j.) cobban" <[email-masked]>
Date: Fri, 12 Jan 1996 11:41:00 -0500

I have encountered an network control request unit on traces between a couple
of PCs running HPR.  It is not documented in GA27-3136 (not surprising
because there are NO NC RUs in that document) or in LY43-0081-2.  It is
obviously APPN related because of the contents.  As formatted by Sniffer the
frame is as follows:

- - - - - - - - - - - - - - - - Frame 2 - - - - - - - - - - - - - - - - -

SUMMARY  Delta T     Destination   Source        Summary
     2    0.671   00           00            SNA C NC code 10

SNA:  ----- SNA Transmission Header -----
SNA:  
SNA:  Format identification (FID) = 2
SNA:  
SNA:  Header flags = 2D
SNA:     0010 .... = Format identification
SNA:     .... 11.. = Only segment
SNA:     .... ..0. = Address field negotiation flag
SNA:     .... ...1 = Expedited flow
SNA:  Destination address = 00
SNA:  Origin      address = 00
SNA:  Sequence number = 0 
SNA:  
SNA:  ----- SNA Request Header (RH) -----
SNA:  
SNA:  RH byte 0           = 2B
SNA:            0... .... = Command
SNA:            .01. .... = RU category is 'network control'
SNA:            .... 1... = FM or NS header follows
SNA:            .... .0.. = Sense data not included
SNA:            .... ..11 = Only RU in chain
SNA:  RH byte 1           = 00
SNA:            0.00 .... = No response requested
SNA:            .... ..0. = Response bypasses TC queues
SNA:            .... ...0 = Pacing indicator
SNA:  RH byte 2           = 00
SNA:            0... .... = Begin bracket indicator
SNA:            .0.. .... = End bracket indicator
SNA:            .... ...0 = Conditional end bracket indicator
SNA:            ..0. .... = Change direction indicator
SNA:            .... 0... = Character code selection indicator
SNA:            .... .0.. = Enciphered data indicator
SNA:            .... ..0. = Padded data indicator
SNA:  
SNA:  ----- SNA NC-RU (Network Control) -----
SNA:  
SNA:  NC code = 10 (Unknown)
SNA:  

ADDR  HEX                                                EBCDIC
0000  18 40 10 00 5A F1 99 9F  10 00 5A 79 91 22 04 04  . ..!1r...!`j...
0010  12 12 2D 00 00 00 00 00  2B 00 00 10 00 66 12 CE  ................
0020  00 01 00 00 00 00 00 00  00 00 00 00 13 60 FB FF  .............-..
0030  72 F7 D9 9B 56 B3 08 C1  D7 D7 D5 4B D7 C3 D1 13  .7R....APPN.PCJ.
0040  2B 01 01 0F 46 0D 80 15  08 C1 D7 D7 D5 4B D7 C3  .........APPN.PC
0050  C8 21 0C 2C 04 08 E2 D5  C1 E2 E5 C3 D4 C7 0B 0E  H.....SNASVCMG..
0060  F3 C1 D7 D7 D5 4B D7 C3  C8 19 80 00 00 00 00 10  3APPN.PCH.......
0070  09 00 00 01 45 00 00 0E  66 00 00 00 00 05 67 03  ................
0080  00 90                                             ..

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From: "jim (j.) cobban" <[email-masked]>
Date: Fri, 12 Jan 1996 16:41:00 -0500

Sorry about that.  I found the documentation in the HPR specification on page
A-39.