Re: [Linux-ATM-General] General doubt in ATM

[Ashish <wri...@gm...>]

I am not quite sure but AAL0 support raw cell so check if your hardware has
support of  ALL0 channel.
if so then open a AAL0 type channel and receive all cells.

--Ashish Gupta

On Thu, Aug 19, 2010 at 11:18 PM, chas williams - CONTRACTOR <
ch...@cm...> wrote:

> On Thu, 19 Aug 2010 19:49:15 +0530
> mahendra varman <mah...@gm...> wrote:
>
> > Hi
> >
> > Is that possible to find what is the VPI and VCI value of a received
> > cell from the trailer or by another means ?.
>
> the vpi/vci is only contained in the header and most of the hardware
> does not expose this in the aal5 layer.
>
> > 1. Suppose in real time if the receiver does not know by what vpi/vci
> > value the transmitter is sending then how to find from the received
> > cells ?
>
> you need an atm analyzer/capture device.  some hardware has the ability
> to receive all the cells regardless of vpi/vci and deliver them to the
> user.  however, this usually cant be done at line speed since it would
> typically generate an interrupt per cell and require quite a bit of cpu
> to handle a full rate oc3, 64-bytes at a time.  the pca200e has a
> special firmware for this.  not sure about any other card.
>
> > 2. Another query is In ethernet reception we can say broadcast address
> > and it will receive from any address. Similarly is there any option to
> > open aread such that it will receive cell of any vpi/vci value ?
>
> nope.  a general solution might be to open all the possible vpi/vci
> values for a card and poll() on all the open fd's.  ugly but
> manageable.  however, most of the atm cards have a limit to the number
> of bits you can split between vpi and vci so they cannot snoop the
> whole spectrum of possible cells.
>
> >
> > Thanks
> > Mahendra
> >
>
>