rgm at ICSA.NET
Tue Feb 20 14:14:46 EST 2001
At 05:42 PM 2/15/2001 +0100, Ole Vik wrote:
>The X.25 stuff is from the middle of 1970s. The X.25 spec is from 1974. I
>worked on an implementation in 1978. We should probably include IBM SNA in
>the history as well. Closed user groups is not a very new invention. In
>SNA IBM uses SDLC, X.25 uses HDLC (link layer protocol). As far as I
>remember, the main difference is the CRC-algorithm used.
the issue here is what is virtual, what is private, and how do you define a
I can argue very strongly, that using named groups to segment a group of
users on a larger network is not virtual. Don't forget NetBios SCOPE which
is still used today.
However, running the network protocol over then network protocol DOES
create a virutal network. IP-n-IP has been around for a while; it is the
basis of the MBONE.
I personally like to limit the use of VPN to the case where over some
network a network is run. Another example is MCI's national frame relay
network which originally was frame relay over IP (on Wellfleet routers).
I also perfer to distinguish if the owner of the VPN controls membership,
or some provider. Thus a Frame relay network made up of PVCs or the older
X.25 equivalent is privated only to the extent that you trust your provider
(and I personally know of cases where the provider was required to include
government agencies in some of these supposedly 'private' networks).
Senior Technical Director
ICSA Labs, a division of the TruSecure Corporation
Fax: (248) 968-2824
rgm at icsa.net
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