ATM switching in MPC8260

ATM switching in MPC8260

[Rudolf Ladyzhenskii]

Hi, all

I have to do some ATM traffic switching using MPC8260. Preferable without
processing data by the 603 core.
AAL2 microcode can do that for AAL2
MPC8260 manual says that it is possible to do it on AAL0

Does anyone know if this is possible for AAL5?

Thanks,

/************************/
Rudolf Ladyzhenskii
DSP Engineer
Advanced Communication Technologies
ph.  +61 3 8080 8215
fax. +61 3 9672 8800
Level 9, 190 Queen Street,
Melbourne, 3000
Australia
/***********************/


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Re: ATM switching in MPC8260

[James Campbell]

Hello,

Its techincally possible.  We have two versions of our 8260/PMC-Sierra
SAR board.  One that directly talks to the control lines of the PMC
chip, and one that uses full 8260 atm support under linux (ported from
the 860 SAR).  Both work well.

Cheers,

James Campbell


On Tue, 2001-12-04 at 20:30, Rudolf Ladyzhenskii wrote:
>
> Hi, all
>
> I have to do some ATM traffic switching using MPC8260. Preferable without
> processing data by the 603 core.
> AAL2 microcode can do that for AAL2
> MPC8260 manual says that it is possible to do it on AAL0
>
> Does anyone know if this is possible for AAL5?
>
> Thanks,
>
> /************************/
> Rudolf Ladyzhenskii
> DSP Engineer
> Advanced Communication Technologies
> ph.  +61 3 8080 8215
> fax. +61 3 9672 8800
> Level 9, 190 Queen Street,
> Melbourne, 3000
> Australia
> /***********************/
>
>
>
--
James Campbell          -|-   Embedded Systems Engineer
jcampbell@omnigon.com   -|-     Omnigon International
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work: +1.760.804.8884 x 332       cell: +1.760.492.1176
--
"Computer games don't affect kids; I mean if Pac-Man
affected us as kids, we'd all be running around darkened
rooms, munching magic pills and listening to repetitive
electronic music."
         -Kristian Wilson, Nintendo, Inc. 1989


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Re: ATM switching in MPC8260

[Dan Malek]

Rudolf Ladyzhenskii wrote:

> Hi, all
>
> I have to do some ATM traffic switching

I'm not sure what you mean by "traffic switching."  The 603 core
needs to be involved for some management of the connections.  I've
done custom Ethernet bridging applications over ATM using the AAL5
and it has worked well.

> MPC8260 manual says that it is possible to do it on AAL0

The AAL0 is just a "raw" ATM cell connection.  Anything over this interface
requires 603 core interaction.  It's purpose is to provide a conduit for
ATM cells that aren't configured for processing by CPM.  Any VCI/VPI the
CPM receives that it doesn't understand is routed here.

> Does anyone know if this is possible for AAL5?

With AAL5 you just hand the CPM a PDU for transmit, and the receiver
returns the PDU in the receive buffer.  The CPM does all of the cell
fragmentation, CRC and length checks, and header processing.

There are many nice features of this ATM controller, including things
like bit rate and cell scheduling.  I suspect the whole of the Linux ATM
software can be done by the CPM (and then some), all we need is a data
path and control interface.

Have fun!


	-- Dan


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RE: ATM switching in MPC8260

[Rudolf Ladyzhenskii]

Hi,

> > I have to do some ATM traffic switching
>
> I'm not sure what you mean by "traffic switching."  The 603 core
> needs to be involved for some management of the connections.  I've
> done custom Ethernet bridging applications over ATM using the AAL5
> and it has worked well.


Management is fine, but I do not want core to process traffic. In case of
AAL2, itcan be programmed to do switching and switching will happen
automatically in CPM.
For AAL0 this is from 8260 manual: "Automatic data forwardingcan be used to
switch AAL0 cells from one ATM port to another without core intervention".
(29.9.8 ATM-to-ATM Data Forwarding).
No mention of AAL5, though.


>
> With AAL5 you just hand the CPM a PDU for transmit, and the receiver
> returns the PDU in the receive buffer.  The CPM does all of the cell
> fragmentation, CRC and length checks, and header processing.
>
> There are many nice features of this ATM controller, including things
> like bit rate and cell scheduling.  I suspect the whole of
> the Linux ATM
> software can be done by the CPM (and then some), all we need is a data
> path and control interface.

Yes, ATM controller is very powerful and flexible. Motorola did a good job!

Rudolf

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Re: ATM switching in MPC8260

[Dan Malek]

Rudolf Ladyzhenskii wrote:



> For AAL0 this is from 8260 manual: "Automatic data forwarding....

I understand now.  If it can also do this for AAL2, there may be a
restriction on switching/forwarding layers that don't require a SAR.
However..........if your AAL5 PDU will fit into a single CPM buffer
it may do it :-).  Just ensure you don't have a LLC/SNAP or other
header in the PDU that may need some adjustment.  The SAR won't know
how to do that.

Have fun!


	-- Dan


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