RE: Bridged networking broken ? (was: Xen works fine)

RE: Bridged networking broken ? (was: Xen works fine)

[JHJE (Jan Holst Jensen)]

Goetz Bock [bock@blacknet.de] wrote:
> I just wanted to provie some more positive feedback. My two Xen
> instalations just work fine. No problem, except for the known 
> (e.g. the broken bridge setup). I'm running Xen 2.0.4 on Debian Sarge
using the
> xen package provided by Adam Heath, with my own 2.6.10 based 
> kernel(s).

I have just started testing Xen for real and I have trouble getting
network connectivity in my VMs. Even though ifconfig reports that
xen-br0 is up in domain 0, my VMs hang trying to obtain a DHCP address.
Is that a known issue with bridged networking - did not find anything
mentioning it in the FAQ ? Would installing the package by Adam Heath
solve this ?

Running on Debian Sarge - using Xen 2.0.4 binary install. Naively just
trying to configure the VMs network by

  dhcp = "dhcp"

Cheers
-- Jan Holst Jensen, Novo Nordisk A/S, Denmark


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RE: Bridged networking broken ? (was: Xen works fine)

[Harry Butterworth]

I've used 2.0.4 on Sarge and the only problem I had was that the
networking scripts fail silently if the 'ip' command is not installed.
Make sure you have it by installing the package iproute.

Harry.



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Re: Bridged networking broken ? (was: Xen works fine)

[Anton Titov]

Actually I've had this problem too, on Gentoo, which comes more or less 
with no packages preinstalled. My network scripts was failing silently 
too and as the server was in colo, the quick solution I found was to 
bring xen-br0 up manually with:

  ifconfig eth0 0.0.0.0 promisc up
  brctl addbr xen-br0
  brctl setfd xen-br0 1
  brctl sethello xen-br0 1
  brctl stp xen-br0 off
  brctl addif xen-br0 eth0
  ifconfig xen-br0 ................. up
  route add default gw ...................

Actually I had very bad problem with machine dropping packets in peak 
hours /~10Mbit network traffic from pages, no big downloads/. I was seening:
Feb 13 22:36:58 carrier ip_conntrack: table full, dropping packet.

in the kernel log all the time, also netstat was reporting many times 
more open connections that was the number of apache processes. I've 
found that there is a bug in connection tracking code, introduced in 
2.6.10 /not sure, but was a recent bug/, I've found a patch for this 
problem, but I was not feeling like patching, recompiling and rebooting 
in peak hours, so I've solved the problem with:

echo 131072 > /proc/sys/net/ipv4/ip_conntrack_max

Hope this helps somebody.

Also does anybody here know about this problem and if it is fixed in xen 
2.0.5, as it is 2.6.10 based too?

Anton Titov


Harry Butterworth wrote:

>I've used 2.0.4 on Sarge and the only problem I had was that the
>networking scripts fail silently if the 'ip' command is not installed.
>Make sure you have it by installing the package iproute.
>
>Harry.
>
>
>
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RE: Bridged networking broken ? (was: Xen works fine)

[Ian Pratt]

> I have just started testing Xen for real and I have trouble getting
> network connectivity in my VMs. Even though ifconfig reports that
> xen-br0 is up in domain 0, my VMs hang trying to obtain a 
> DHCP address.

Is your DHCP server configured to hand out addresses to any MAC address?

Ian


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RE: Bridged networking broken ? (was: Xen works fine)

[JHJE (Jan Holst Jensen)]

> > I have just started testing Xen for real and I have trouble getting
> > network connectivity in my VMs. Even though ifconfig reports that
> > xen-br0 is up in domain 0, my VMs hang trying to obtain a 
> > DHCP address.
> 
> Is your DHCP server configured to hand out addresses to any 
> MAC address?

It should be - I've never had trouble setting up machines on our
network.

-- Jan


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RE: Bridged networking broken ? (was: Xen works fine)

[JHJE (Jan Holst Jensen)]

> with no packages preinstalled. My network scripts was failing 
> silently 
> too and as the server was in colo, the quick solution I found was to 
> bring xen-br0 up manually with:
> 
>   ifconfig eth0 0.0.0.0 promisc up

Thanks for the suggestion. I'll try it end of next week when I am in the
office again. Tried shutting xen-br0 down before doing the above but
then lost network and so my ssh connection - DUH! One machine offline,
9999 to go :-). Well... better luck on thursday.

Cheers
-- Jan


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