[Spread-users] Spread 4.0 daemon "goes to sleep" on XP network disconnect

[Steve Duff]

Hi,

Thanks for taking the time to reply.

You are correct that spsend cannot send to the local IP address when the
network card has been disconnected - it can send to 127.0.0.1, but
spread is not using this address for "send to self".

It appears that unlike other OS's, XP deletes (or makes inaccessible)
the entire interface configuration when it detects the failure of the
network connection, so can't possibly route traffic to the local IP
address. 

According to one of my colleagues, previous versions of Windows, e.g.
Win2k, do not do this. I'm sure that Microsoft has a good reason for
introducing this behaviour in XP, but I can't think what it might be.

Thanks again for your help.

Steve

-----Original Message-----
From: Yair Amir [mailto:yairamir at cs.jhu.edu] 
Sent: 08 August 2007 15:36
To: Steve Duff
Cc: spread-users at lists.spread.org
Subject: Re: [Spread-users] Spread 4.0 daemon "goes to sleep" on XP
network disconnect

Hi,

It looks to me that in your case, the operating system does not pass
messages
from the machine to itself when you unplug the cable. This means that
Spread cannot send a unicast to itself on the local node. You can verify
this by
using the two programs spsend and sprecv provided with Spread (you may
need to build them - "make spsend", etc.)

Run both of them on the singleton machine before you unplug to verify
that unicasts from spsend to sprecv using the IP address from the
configuration file will be received. Then, unplug and try again.
Then plug and try again. If my observation is correct,
spsend will not be able to pass messages to sprecv on your system
locally
on the same machine when the cable is unplugged. It may be that it
even drops the whole interface if the cable is not plugged.

Let us know if this is the case.

Cheers,

	:) Yair.


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