[Beowulf] PVM on wireless...

Jim Lux James.P.Lux at jpl.nasa.gov
Wed Feb 6 17:16:13 EST 2008


At 01:28 PM 2/6/2008, Robert G. Brown wrote:
>On Wed, 6 Feb 2008, Reuti wrote:
>
>>Just an idea to check: PVM can also be started without rsh/ssh 
>>between the machines. You have to copy and paste some things from 
>>here to there and back and can startup all daemons this way by hand 
>>(page 30 in the PVM book). Maybe this works - just to narrow the cause.
>
>I'll look into this, thanks, although the daemon IS started -- the block
>it is somewhere after that.  But it is well worth trying anyway.
>
>I also wonder about ports and WAP interactions.  I've got my WAP
>configured (AFAICT) as an internal switch, not really as a router.  As
>in my laptop get DCHP service from my linux server, not the WAP, which
>is flat to broadcasts, has no port filtering on the internal network
>etc.

Ahh.. but there is a "routing" process of sorts inside your AP.  It 
has to bridge from the 802.3 wired world to the 802.11 wireless 
world, and that usually involves some store and forward type 
processing.  Some of these are implemented as a store and forward 
router (e.g. home firewall) with one of the logical ports connected 
to the wireless modem.  Very, very few access points (if any) are 
actually a dumb packet oriented bridge that just unwraps the payload 
from one frame type and shoots it out rewrapped for the other.  The 
AP has to do things like send out broadcast frames with the SSID, 
send and receive the link setup/teardown kinds of frames (i.e. the 
link between your PC's wireless interface and the AP), as well as 
bridging/routing traffic from the wired network to the wireless network.

Who's to say what kind of logic they have inside there to deal with 
all the issues (the wireless MAC and the wired MAC are different, if 
nothing else.)

Jim Lux


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