Re: [Xen-users] DomU hangs sporadically

["Fajar A. Nugraha" <fajar@xxxxxxxxx>]

On Thu, Jan 22, 2009 at 11:52 PM, Jonathan Weismann <jweismann@xxxxxxxxx> wrote:
> I had to move to another machine with Xen 3.2 that I compiled from source, I
> deployed the same image and when I ping one host to the other (2 DomU's on
> the same server sharing the same bridge)  I get:
>
> Destination Host Unreachable

If it's a similar setup (same versions, similar hardware, same image,
same config) then maybe you're just forgetting something. Perhaps
iptables is still turned on on this test machine and preventing
traffic coming through? try iptables -nL (on dom0), and snipping
packets (with tcpdump) on dom0's bridge on domU's interfaces during
ping.

The point that I was trying to make is :
- if all traffic can't go through (like your test setup), most likely
you're forgetting something basic : iptables, ip address/subnet setup,
your bridge is still down (e.g. created it manually but forgot to run
"ifconfig brtest up"), etc.
- if some domUs traffic can't go through all the time (example : ICMP
works, but TCP connections broken) then it's most likely MTU problem
- if domU <-> domU and domU <-> dom0 traffic on the same machine
works, but domU <-> outside world broken, then most likely something
wrong with network card (driver or hardware)
- if domU <-> domU and domU <-> dom0 traffic on the same machine
works, but domU <-> outside world SOMETIMES broken, I tend to suspect
that it's basic general networking problem : conflicting MACs, flaky
switches, problematic routers, etc.

Regards,

Fajar

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