[cisco-bba] ATM : VP & VCI

[raghuram chary]

Doug Thanks for the reply.But I couldnt understant what you are saying.


On Sat, Jan 3, 2009 at 1:23 AM, Doug McIntyre <merlyn at geeks.org> wrote:

> On Fri, Jan 02, 2009 at 08:05:35PM +0530, raghuram chary wrote:
> > Hi all,I'm unable to understand/imagine the VP and VC concept in ATM
> > technology.Can anyone explain the concept in detail?Any website pointers
> or
> > animated videos will also be appreciated.
>
> Its much like a DLCI in frame relay or a VLAN tag in ethernet networks..
>
> An identifier to mark this cell/packet/frame/whatever is identified
> with this number and we differentiate that from other cells that could
> be for other things.
>
> As to the reason for splitting the identifier into two seperate ones,
> ATM allows you to do path switching as well as VPI switching. You can
> take everything within the same VPI and push it out a different port
> than another.
>
> You could have all of customers X traffic on VPI 10, and all of
> customer Y's traffic on VPI 11. Now, no matter how many VPI's customer
> X lights up, your switching setup continues to work without additional
> setup on your switching gear.
>
> There's reserved VCI's so that also comes into play (ie. why the first
> PVC may be on 0/32 instead of 0/0 like you'd expect).
>
>
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