Question about NPI/streams programming for AIXlink./X.25

Question about NPI/streams programming for AIXlink./X.25

Post by John Cowli » Fri, 08 Feb 2002 22:26:50



Given that the ITU-T Recommendation X.25 (03/93) standard states in
Appendix IV.4 that: "Some other networks allow the DTE to include in
the call accepted packet none, one or both of the two DTE addresses."
can anybody tell me which of these three options the NPI api supports?
The example programs only demonstrate how to fill the called address
field in an N_CONN_RES primitive. Is it possible to fill both address
fields in the address block, or is it possible to leave the address
block out altogether (as xtalk does)?
 
 
 

1. AIXlink/X.25 question (about using the NPI API)

Hallo,

Environment: AIXlink/X.25 1.1.5; 2 port multiprotocol pci adaptor.

I'm trying to establish an svc across a vpn. The remote system is
responsible for call initiation.

Background: If I use xtalk and choose ACCEPT when the incoming call
arrives I see in x25mon that a 'call accepted' is returned and in
xtalk and x25status I see that that the svc is established. x25mon
shows that the call accepted frame contains (hex) 10010F. The '10' is
a general format identifier and logical channel group number; the '01'
is the number of the logical channel the call is established on; the
'0F' is the packet type identifier for a Call Accepted packet. There
seems to be no address block, facilities or CUD, which (as I
understand the standard) are optional.

Now the problem: if I try the same programmatically (using the sample
program npiserver.c as a starting point) I see in x25mon that my Call
Accepted always contains an address block, and the network is
rejecting these packets with diagnostic code 0x20 (packet not
allowed). By manipulating the call to the N_CONN_RES primitive in the
program I can generate a Call Accepted containing 10010F00 (address
block with called and calling address lengths of zero), or (for
example) 10010F091234567890 (9 digit Called Address with one nibble of
padding). I can't work out how to suppress the address block
completely (as in the working xtalk example), or to send a complete
address block with both addresses (or indeed a facilities or CUD
block).

I know that xtalk uses the (deprecated?) COMIO api, but it does at
least give me a working reference point, and the impression that the
vast array of configuration parameters are compatible with the cloud
and the remote host which initiates the call. (Am I being naieve
here?)

If the collected braincells out there could give me any tips as to
where to go from here then I would be most appreciative,

John Cowling.

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