[rhos-list] Cirros VM image DHCP issues

[Andrew Cathrow]

----- Original Message -----
> From: "Perry Myers" <pmyers at redhat.com>
> To: "Derrick H. Karimi" <dhkarimi at sei.cmu.edu>, "Livnat Peer" <lpeer at redhat.com>, "Maru Newby" <mnewby at redhat.com>,
> "Brent Eagles" <beagles at redhat.com>, "Robert Kukura" <rkukura at redhat.com>
> Cc: rhos-list at redhat.com
> Sent: Friday, September 6, 2013 10:25:13 AM
> Subject: Re: [rhos-list] Cirros VM image DHCP issues
> 
> On 09/06/2013 08:42 AM, Derrick H. Karimi wrote:
> > I have seen the similar  issue (also happens with some Ubuntu images), this
> > solved it for me
> > 
> > iptables -A POSTROUTING -t mangle -p udp --dport 68 -j CHECKSUM
> > --checksum-fill
> 
> Is that a rule you put in the guest or on the host?
> 
> Do you only see this issue on Cirros images or by chance do you see it
> with Fedora or RHEL images as well?
> 
> > taken from here
> > http://serverfault.com/questions/448347/instances-in-openstack-are-not-getting-dhcp-leases
> 
> There was some talk on this thread that if virtio networking is enabled,
> this behavior doesn't occur...  What did you find?

I learned, from a smarter man than I, that ...


<snip>
It's an old bug in dhclient on Linux - dhclient doesn't work well
with RX checksum offloading enabled.
Recent Red Hat and Ubuntu derivatives have fixed it,
debian didn't yet ...
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=652739
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=671707
</snip>


> 
> Perry
> 
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