Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!rutgers!att!ima!haddock!news
From: news@haddock.ima.isc.com (overhead)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: IP <-> X25 address mapping/conversion question
Keywords: IP, X25
Message-ID: <15363@haddock.ima.isc.com>
Date: 6 Dec 89 21:43:23 GMT
References: <6539@tolerant.UUCP>
Reply-To: jimm@ima.ima.isc.com (Jim McGrath)
Distribution: usa
Organization: Interactive Systems Co
Lines: 29

In article <6539@tolerant.UUCP> hahn@tolerant.UUCP (John Hahn) writes:
>
>I am looking for some information on the Internet Ip-addr to X25
>address mapping/conversion issue. I always assumed that in order to
>have TCP-IP run on top of X25 the addresses have to be mapped since
>Internet and X25 address spaces were incompatible. However when I
>was investigating the BSD4.3 implementation on the VAX it looks as if
>there is an address conversion based on some DDN spec. 
>

"Defense Data Network X.25 Host Interface Specification" Dated
December, 1983, prepared by BBN Communications Corporation.  Refer to
Section A-5 of Appendix A.

>Which then brings up the question if this is useable with the 
>Public Data Networks (i.e. Telenet, Tymnet, Transpac ..etc)? 
>Is this only for some DDN private networks and one must resort to 
>mapping the address for use with the PDN's?
>

Each Public Data Network (and DDN) assigns its own address space.
There are no address conversion algorithms that I know of except for
the DDN address space.  

I believe there was a posting a while back about about a group working
on an ARP type protocol to obtain X.25 addresses, but I may be wrong
about this.

Jim