10/100 NICs

[Donald Becker]

On Mon, 12 Mar 2001, James Alton wrote:

> When building a beowulf, especially when using cheap 10/100 cards,
> performance matters a lot. Thatt is why I am asking the question of, if I am
> going to buy a 10/100 card, what is faster? A Kingston card, or a 3com 905B
> card?

The 3c905B will usually win, since it can
   Receive into arbitrarily aligned Rx buffers
   Calculate UDP/TCP/IP checksums in hardware

The tulip design has an excellent multicast filter, and should be used
when there is heavy multicast traffic.  Note that some of the tulip
clones (ADMtek and ASIX) omit the 16 element perfect filter and 512 slot
hash filter, instead substituting only a 64 slot hash filter.

> Is there a page that shows benchmarks of 10/100 cards?

The benchmarks vary by the CPU in use.  The Rx alignment doesn't matter
with some CPUs, but is a killer with the IA64 and Alpha.

> Would a cheapo
> realtek card (10/100) get the same performance as far as speed?

No -- the RTL chips require the CPU to do an extra copy for every packet
transferred, both Rx and Tx.

> Also, is gigabit worth it to put in every node? (What type of speed
> would I expect from gigabit? 1000Mbits/sec? lol.)

It depends on the cost.  Right now the switch cost is the real issue.

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