ATM switching in MPC8260

Rudolf Ladyzhenskii rudolf.ladyzhenskii at
Thu Dec 6 09:18:25 EST 2001


> > 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!


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