Xen and network issues.
Warren Togami
wtogami at redhat.com
Tue May 8 19:21:47 UTC 2007
Mike McGrath wrote:
> We've got issues. Many of our xen guests are experiencing tcp checksum
> corruption. Research on the net suggests ethtool -K eth0 tx off will
> fix the issue but it hasn't in our case. I've tried the koji guest on
> many physical hosts, same issue. It's been on two FC6 dom0 hosts and a
> RHEL5 dom0 host.
> For now I'm going to stick koji on app1 as a physical host. Just
> because that box has gotten to the point where it becomes unusable and
> we cannot have that happening right now.
>
> I've contacted some internal xen developers, some guys in ##xen on
> freenode and the Fedora-xen list. Anyone who is able I'd encourage you
> to take a look as well. Simple test:
>
> "tcpdump -vvv | grep incomplete"
>
> You'll see:
> 06:34:20.135530 IP (tos 0x0, ttl 64, id 39370, offset 0, flags [DF],
> proto: TCP (6), length: 40) nat-pool.fedora.phx.redhat.com.49457 >
> publictest8.fedora.phx.redhat.com.http: P, cksum 0x76af (incorrect (->
> 0x6100), 601:601(0) ack 6801 win 597
>
If worse comes to worse I know a workaround for this that eliminates the
problem, but also adds a bit more inconvenience. It involves creating a
private NAT network on each Xen host, with the extra real IP on the
hosts real ethernet device, and NAT.
Warren
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