Cell Relay Archive

[Anil kumar Gupta <akgupta@npi.stpn.soft.net>]

Hi,
Normalluy all VPI/VCIs  are not used in the switch and a limit is kept on
number of VPI, VCI'c that can be created in a particular interface/line.
Using this number they convert each VPI/VCI to some internal number in this
range( input point ). This internal number is then used through out the
switch and converted again to outgoing VPI/VCI before sending out.  For
example you allow only 1024 VCI's but any VCI's in the range of 32-64K can
be used.
Further, to shorten the look up time, the number can be  broken into
multiple part. and then each part is seperately used to index the diffrent
tables directly (as you will index a array). This is something like making a
chain of linked pointers where final.

Anil
mrityu wrote:

> Hi,
>
> Actually, I have a related question: can some one please explain how the
> VPI/VCI values are actually managed in a switch. I mean what kind of
> data structures do they use and what is the order of magnitude of their
> search time. Linear allocation is simple, but it also will have to take
> care of random allocations as in the case of PVC creation.
>
> Thanks,
>
> Mrityunjay
>
> In article <3776D695.10A55987@ccunix.ccu.edu.tw>,
>   Meng-Hsi Chiu <d8342012@ccunix.ccu.edu.tw> wrote:
> > Did there exist any information of  an SVC implementation in atm
> switch like
> >
> > "most vendors would scan from 32 up and pick up the first free VCI."
> >
> > Thanks a lot.
> >
> > No Spam wrote:
> >
> > > Meng-Hsi,
> > >
> > > For PVC's the network admin assigns the VPI/VCI's by himself so the
> switch
> > > doesn't make any decision. For SVC's the algorithm is vendor
> specific
> > > although most vendors would scan from 32 up and pick up the first
> free VCI.
> > >
> > > Yan.
> >
> >
>
> --
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