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Re: [Linux-cluster] OT? Odd Xen network issue



Edson Marquezani Filho wrote:
On Mon, Oct 26, 2009 at 16:33, Madison Kelly <linux alteeve com> wrote:
Hi all,

 I hope this isn't too off-topic being more a Xen than cluster experience,
but I am having trouble with the Xen mailing list and I gather many here use
Xen. If it is too off-topic, the please have a mod delete it and kick my
butt. :)

I've got a simple two-node cluster, each with three NICs running CentOS 5.3
x86_64. Each node has this configuration:

eth0 - Internal network and VM back channel (IPMI on this NIC)
eth1 - DRBD link
eth2 - Internet-facing NIC, dom0 has no IP

I have a very similar setup here.

So far, it seems like a pretty decent low-cost, high availability setup. :)

 I've built a simple VM that uses 'xenbr0' and 'xenbr2' as the VM's 'eth0'
and 'eth1', respectively. I've set a static, public IP to domU's eth1
(xenbr2) but I can't ping it from a workstation nor can the domU ping out. I
know that the network itself (outside the server) is setup right as I tested
the static IP from that cable earlier on a test machine.

This sounds to me like being related only to routing stuff, rather than Xen.
I don't know if what I'm going to say is already implicit in what you
said, or very obvious to you, but to reach that public IP address in
question, the workstation from where you are trying to do this must to
have a route that leads to this IP, usually a gateway address.
Try thinking about the path the packet is following across the
network, and if there is routing rules enough to reach its destiny.

Even from dom0, you are subjected to the same rules. For example: to
ping some public IP address assigned to a domU's eth1, you should have
either a IP of the same network assigned to your physical eth2/peth2
(or a virtual ethX interface atached on xenbr2 bridge), or routes that
leads your packet from your dom0 to that domU's IP.

Before I began work on Xen I had assigned the public IPs to eth2 and it had worked. For some reason, Xen + 64bit + D-Link DGE-560T = no luck. I took a cue from this email to check traffic on xenbr2 on dom0 and I could see traffic while debugging. As I mentioned to Rick, I could see the ICMP requests up to vif0.2, but not on peth2.

 Could someone hit me with a clue-stick as to what I might be doing wrong?
Let me know if any logs or config files are helpful.

I'm not sure if I understood your scenario correctly, and I don't know
if I could be clear enough with this bad english, but at least, I
tried. =)

Pfft, your English is awesome. :)

Thanks!

I hope this can help a bit. Good luck. =)

It did. Once I saw it hit vif0.2 I knew that bridging was working and that it was likely a hardware/driver bug.

Thanks!

Madi


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