NIC to avoid...?

Martin Siegert siegert at sfu.ca
Tue Aug 28 14:42:30 EDT 2001


On Tue, Aug 28, 2001 at 11:32:38AM -0400, Michael Sowka wrote:
> Can someone please clarify something for me... I was just about to fill 
> out a PO for our upcoming 16 node cluster when I stumbled upon this info 
> concerning the 10/100 NIC card (read: that's the card I plan on using :( ):
> http://oscar.sourceforge.net/notes.php
> What exactly does that mean... should I stay away from this NIC... and 
> what NIC do you guys recommend?! Performance is the key as we're blowing 
> a fair amount of money and a Cisco Catalist 3500 Switch....

With respect to the NIC:
I believe you are refering to the following section on the web site above:

<quote from http://oscar.sourceforge.net/notes.php>
Problem Hardware:
-----------------------

- 3Com 3C905CX-TXNM Ethernet Adapter
There are two problems associated with using the 3C905CX-TXNM adapter. 
1. The adapter does not support network booting using PXE. 
2. The network boot kernel provided with LUI contains a driver (3c59x) that
   does not properly initialize this adapter, rendering it unable to receive
   data.

It is suggested that you avoid this adapter completely if at all
possible.
</quote>

Firstly, if you really want to know whether there are problems with that
card you should post your question to the linux-vortex mailing list,
see http://www.scyld.com/network/vortex.html.
Secondly: I don't know anything about OSCAR and why they have problems with
3C905C cards, but if I had to choose between OSCAR and 3c905 cards I would
choose the 3c905 cards: In all my benchmarks that I have done on 100baseT NICs
the 3c905 cards with the 3c59x driver showed the best results. I just ordered
a 70 node beowulf cluster with two on board 3c920 NICs and two 3c905CX-TXM NICs
in each node. All of them use the 3c59x driver. On my test system netpipe
(NPtcp) shows a latency of 43us and a bandwith of 89.8 Mbit/s between two
3c905C cards and 52us / 269.2 Mbit/s latency/bandwidth using 3 NICs on
each node in a channel bonded configuration. I don't think that you can do
much better than that. (There is another benefit with 3c905c cards: they
are so slim that you can plug them directly into the PCI slots of the
motherboard even in a 2U case - no need for a riser card).

With respect to the quotes from the OSCAR web site:
1) I do not know whether/why the 3c905CX-TXNM doesn't support PXE - I don't
   use PXE.
2) This is a strange remark: Why don't they upgrade the kernel instead?
   AFAIK there are no issues with the 3c59x driver in kernels 2.2.19 and
   later including the 2.4.x kernels.

In short: With respect to the 3c905c cards in general I can't agree with
the suggestion from the OSCAR site at all. With respect to 3c905c cards
working with OSCAR specifically I can't comment - I'm not using OSCAR.


Martin

========================================================================
Martin Siegert
Academic Computing Services                        phone: (604) 291-4691
Simon Fraser University                            fax:   (604) 291-4242
Burnaby, British Columbia                          email: siegert at sfu.ca
Canada  V5A 1S6
========================================================================

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