Ethernet-Gigabit-Myrinet in one system

Patrick Geoffray patrick at
Fri Jul 19 09:00:26 PDT 2002

Hi Ivan,

Ivan Oleynik wrote:
> Tyan i7500 motherboards contain built-in Gigabit Ethernet and Fast
> Ethernet. What are the best ways to utilize these additional resources in
> the system that will contain Myrinet interconnect as a base communication
> infrastructure. Are there any substantial advantages to link the nodes via
> additional Etherner or Gigabit switch to get substantial speed up of

Yes, it's definitively a good idea to have Ethernet at the same time. 
First of all, Ethernet (100) is "free": the NIC is on the motherboard 
and the switch/hub solutions are very inexpensive. It's usefull for 
several reasons:
* you can put all of the administrative IP traffic on it (rsh/ssh, NIS, 
batch queue daemons traffic, etc). Everything that is very happy with 
the speed of Fast Ethernet should go there.
* IP traffic that produces IP broadcast: Myrinet is a switched fabric, 
without "Store-and-Forward" capability, so IP broadcast (ARP request) 
generates *a lot* of messages. Fast Ethernet is better suited for this 
type of IP traffic.
* It's always good to have a network access when you shutdown Myrinet
or update drivers.
* If the NFS traffic is limited, it can be put on this network too.

My 2 centimes.


|   Patrick Geoffray, Ph.D.      patrick at
|   Myricom, Inc.      
|   Cell:  865-389-8852          685 Emory Valley Rd (B)
|   Phone: 865-425-0978          Oak Ridge, TN 37830

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