sure.. PPP (point-to-point protocol) and Frame relay are both different
layer two protocols that run on top of the T-1 service. PPP over T-1 is
the same PPP the is commonly used for modems when dialing up to an ISP.
It's based on the HDLC protocol.
Frame relay has an addressing scheme separate from IP that makes it a
shared protocol that can be switched throughout a telco providers switch
network. It uses the concept of a DLCI (Dynamic Link Channel
Identifier) and of SVCs and PVCs to implement a point-to-point or
point-to-multipoint scheme connecting many sites over a single physical
circuit. Essentially, the provider can say ok, here's a PVC (Permanent
virtual circuit) at DLCI 16 that points to company B, and here's another
that points to Company C on dlci 17. you set these up on your side, and
then the provider gives the other companies their own dlci numbers that
correspond to that circuit connection. SVCs do the same thing but on an
as-needed basis. many providers don't support these. frame relay also
provides LMI (local mgmt. interface) to list DLCI numbers and assure
connectivity (among other things) to a FRAD (frame relay access device).
it's important point to note that because of frame relay's features and
the fact that it is switched (PPP is mapped directly from point A to
point B by the provider), mean that overhead is incurred and a portion
of the total circuit bandwidth will be used by the protocol. So, a T-1
won't be able to run at a full T-1 speed over frame relay, and the
network won't provide you assurance of that unless you give them lots of
money. This gets into congestion control (FECN and BECN) and the
concept of CIR.
Many of these terms (HDLC, frame relay, PPP, T-1, etc.) are fairly well
definied with links to further explanations at http://www.whatis.com.
i love network acronym speak. it makes me feel like a doctor.
hope this helps,
david
John Zaggat wrote:
>
> Can some clearly explain the difference, I have
> checked the Archives and not found a good explanation.
> Also if you have some sample configs, that would be a
> great help to me.
> Thank you.
>
> =====
> JZ
> [EMAIL PROTECTED]
>
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