[Beowulf] Wireless network speed for clusters

Jim Lux jimlux at earthlink.net
Sat Mar 20 17:42:54 EST 2004


Some preliminary results for those of you wondering just how slow it
actually is...

Configuration is basically this:

node (Via EPIA C3 533MHz) running freevix kernel (ramdisk filesystem)
wired connection through Dlink 5 port hub
DWL-7000AP set up for point to multipoint 802.11a (5GHz band)

luminiferous aether

DWL-7000AP
ancient 10Mbps hub
    Clunky PPro running Knoppix/debian
    Maxtor NAS with a NFS mount

Pings with default 63 byte packets give 1.2-2.0 ms both ways...
Compare to <0.1 ms with a wired connection (i.e. plugging a cable from the
Dlink hub to the ancient hub)

DHCP/PXE booting sort of works (not exhaustively tested)
For some reason, the nodes can't see the NAS so NFS doesn't mount

There are a lot of "issues" with the DWL-7000AP... I think it's trying to be
clever about not routing traffic to MACs on the local side over the air, but
then, it doesn't know to route the traffic to the NFS server. The DWL-7000's
also don't like to be powered up with no live (as in responding to packets)
device hooked up to them, so there's sort of a potential power sequencing
thing with the EPIA boards and the DWL-7000AP.

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