Follow up to ATM and VPN's

Roelof JT Jonkman rjonkman at ITTC.UKANS.EDU
Wed Apr 5 16:43:46 EDT 2000


Jeffrey,

Somewhat rethorical question:

What is the purpose of vpn over frame relay circuits?

Dito with ATM.

ATM is not a VPN, ATM has the ability of segregating traffic very nicely, plain
IP doesn't, herein lies the major difference, ip routing requires parts of the ip
packets, namely the header to be readable and legit. If you pipe it over and
ATM VC (dito for a FR VC) you can shovel whatever you like over it as long as it
fits within the ATM mess. (AALx 0<x<5 most likely, and this statement implies:
ATM end to end.)

Dunno what the exact definition of a vpn is, if you believe telco's its
just a logically seperate network, the bulk of the people on this list
understand vpn to be something that encrypts at the minimum. VPN is probably
not exclusively IP, if I'd were to have a VPN between multiple branches I'd
probably want to pipe a bunch of legacy cruft between these too, say my old
novell 3.11 clunker that I haven't turned over to ip yet.

ATM (or FR for that matter) simply can give you a level of logical seperation,
that nothing else can give you at this point. (MPLS VPN's maybe, if that ever
to go anywhere.....) That is really all that it buys you in regard to VPN
features.

roel

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