GigE fiber NIC

Donald Becker becker at scyld.com
Thu Sep 27 17:00:09 EDT 2001


On Wed, 26 Sep 2001, Joel Jaeggli wrote:
> On Wed, 26 Sep 2001, Martin Siegert wrote:
> 
> > - 3Com 3c985B-SX
> > - Netgear GA620
> > - Syskonnect SK-9843
> > - National Semiconductor DP83820
> >
> > Intel makes GigE cards as well, but the driver is not distributed with
> > the kernel. Thus I would rely on Intel to have a driver available when
> > I want to upgrade the kernel.

We have an alternate Intel driver named intel-gige.c, however its
continued evolution does depend on development information from Intel.

> I'd probably go with the sysconnect for performance/support followed by
> the ga620 which is the cheapest of the acenic (the differences
> between them aren't substantive)based cards.
> 
> the nat semi chipset has the distinction of being really cheap (the
> 10/100/1000 copper cards from dlink are $89. but the chipset on has an 8k
> transmit and 32k recieve buffer which makes it not the most desireable for
> a high-end gig card...

The primary performance limitations of the NatSemi chips are
  Must receive into word-aligned Rx buffers, which misaligns the IP
    header and payload.
  No UDP/TCP/IP checksum support, or other network work "offload".

The 8KB/32KB on-chip FIFOs don't limit the chip in most systems, nor
does the limit of a 1KB burst have a big impact.  (Some chips, such as the
3c905CX, can burst a whole 1514 byte packet.)


Donald Becker				becker at scyld.com
Scyld Computing Corporation		http://www.scyld.com
410 Severn Ave. Suite 210		Second Generation Beowulf Clusters
Annapolis MD 21403			410-990-9993


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