🚀 go-pugleaf

In article <1152@cbnewsh.att.com> cheng@cbnewsh.ATT.COM (wan-hong.steve.cheng) writes:
>Is there any difference between DDN X.25 interface and CCITT X.25 interface 
>standard (198?) ?  I understand there is a certification procedure to pass 
>before connection to DDN can be done.  Does anyone know the details?  Thanks 
>for your information.

The DDN (MilNet, APRAnet and clones) is a bona fide CCITT X.25 1984
compliant network (although it does not seem to have a DNIC).

Due to the requirements for stability of the applications that run on
this network, the owners have instituted a certification program. Most
X.25 network operators will not allow connection of customer equipment
without prior certification, but the DDN certification procedure is the
most rigorous I have seen. (It tests the error detection and error
handling capability of the host as well as normal operation).

What is special about the DDN is that most of the traffic is known to
be TCP/IP, and the network is optimized for TCP/IP traffic. Special
ports are available to hosts that speak no X.25 but speak BBN-1822 AHIP
(ARPAnet Host-to-Imp-Protocol), and the network performs protocol
conversion as needed. In order to be able to exchange traffic with
these hosts, most TCP/IP hosts specify "Standard Mode Facility" at call
setup time.

Also, there is an algorithmic correspondence between physical
attachment point (PSN number, port number), IP address and X.25
address.

Also, instead of PADs for asynch terminals, DDN has TACs; i.e. dial-up
asynch terminal service uses TELENT protocol instead of X.29.
/ Lars Poulsen <lars@salt.acc.com>     (800) 222-7308  or (805) 963-9431 ext 358
  ACC Customer Service                Affiliation stated for identification only
                  My employer probably would not agree if he knew what I said !!