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List:       linux-atm
Subject:    Re: NIC with large VP/VC range
From:       djholm () fndaub ! fnal ! gov (Don Holmgren)
Date:       1997-10-24 15:02:49
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> 
> I am loooking for an ATM adapter (155 NIC) supporting a very large
> number of PVCs (very low bit rate). My preference would go to a NIC that
> supports (in and out) different VP values (up to 256 ideally). However,
> if I can't find that, a NIC supporting the entire range of VC values
> would be fine as well. I would write the driver to take care of SAR
> functions.
> Any idea whether such a NIC exists and where?
> Thanks
> 
> 
> Patrick Pfeffer
> 

We're using FORE ForeRunnerLE cards with a modified nicstar driver
(they use the same IDT chipset).  By modifying the nicstar.h file
you can choose a combination of bits allocated to VP and VC values
for indexing into the card's connection table.  The bit count
available depends upon the amount of SRAM on the card.  Here's the
piece from nicstar.h which controls this:

    /* Valid combinations for VPI/VCI:
                   4k table, no VPI, 12b VCI (set CFG_VPIVCI to 0x00000)
                   4k table, 1b VPI, 11b VCI (set CFG_VPIVCI to 0x40000)
                   4k table, 2b VPI, 10b VCI (set CFG_VPIVCI to 0x80000)
                   4k table, 8b VPI,  4b VCI (set CFG_VPIVCI to 0xc0000)
        *** below only for boards with 128k x 32b SRAM ***
                   8k table, no VPI, 13b VCI (set CFG_VPIVCI to 0x10000)
                   8k table, 1b VPI, 12b VCI (set CFG_VPIVCI to 0x50000)
                   8k table, 2b VPI, 11b VCI (set CFG_VPIVCI to 0x90000)
                   8k table, 8b VPI,  5b VCI (set CFG_VPIVCI to 0xd0000)
                  16k table, no VPI, 14b VCI (set CFG_VPIVCI to 0x20000)
                  16k table, 1b VPI, 13b VCI (set CFG_VPIVCI to 0x60000)
                  16k table, 2b VPI, 12b VCI (set CFG_VPIVCI to 0xa0000)
                  16k table, 8b VPI,  6b VCI (set CFG_VPIVCI to 0xe0000)
     You will need to define each of the below to match the desired config
     */
    #define RX_CTABLE_ENTRIES (4 * 1024)
    #define CFG_VPIVCI      0x000c0000
    #define NUM_VCI         (16)
    #define NUM_VCI_BITS    (4)     /* Number of bits required for above */
    #define NUM_VPI         (256)
    #define NUM_VPI_BITS    (8)     /* Number of bits required for above */

As you can see, we're using VP's from 0 to 255, and VC's from 0 to 15.  The
default was to allocate all bits to the VCI.

The modified nicstar driver which supports the ForeRunnerLE is available 
at
  ftp://linux-rep.fnal.gov/pub/drivers/atm-nicstar/


Don Holmgren
Fermilab
Batavia, IL, USA

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