problem with network bridge br0

Thorsten Göllner Fri, 18 May 2012 03:29:19 -0700

Yes, it was another typo. Sorry for that.

My kvm host is attached to a switch with another 4 servers in our rack (it is mesh solution düsseldorf and not hetzner).

I tried the following as suggested by serge: On another server connected to my switch I started tcpdump. On my guest I started a ping to the server with tcpdump. I can see, that the ping packet on the guest starts an arp request. My server (with running tcpdump) replies to the arp request correctly. In the guest I can see a correct arp table:

~# arp-n
Address          HWtype HWaddress         Flags Mask   Iface
113.203.209.161 ether   00:15:17:0e:6a:a9 C             eth0
113.203.209.162 ether   00:22:15:41:13:23 C             eth0

The first entry is that of my default gateway. The second one is that of my server running tcpdump.

On the server running tcpdump (server name ist nostradamus2) I can see that:

# tcpdump host 113.203.209.165
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
12:28:19.370690 ARP, Request who-has nostradamus2 tell 165.209.203.113.static.inetbone.net, length 46
12:28:19.370703 ARP, Reply nostradamus2 is-at 00:22:15:41:13:23 (oui Unknown), length 28

So the question sould be: why does the guest not receive the arp reply from my server?!

Am 18.05.2012 11:52, schrieb Michael Zoet:

Hi,

Am 18.05.2012 10:57, schrieb Thorsten Göllner:
Sorry, my fault. I had a typo. The broadcst is configured correctly: 113.203.209.191

Any other idea?

yes but may be it is another typo:

ON THE GUEST:
=============
~$ ifconfig
eth0      Link encap:Ethernet   HWaddr 52:54:00:d2:d1:73
          inet addr:113.203.209.165 Bcast:213.203.09.191   Mask:255.255.255.224
[...]

~$ route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         113.203.209.161 0.0.0.0         UG    100    0        0 eth0
1213.203.209.160 0.0.0.0         255.255.255.224 U     0      0        0 eth0

An IP of 1213.203.209.160 in your default route does not exist in IPv4 ;-). The 1213 is much too high ;-) and I think the 2 should be deleted. But I also think your routing is not correct. In my opinion there should be 113.203.209.163(the IP of your KVM host) instead of 113.203.209.161 and 113.203.209.0 instead of 1213.203.209.16.
But these are only guesses and it depends on how routing is done in your data center. (I think you are using Hetzner and Hetzner does not allow you to use their gateway with other MAC addresses than your KVM host!) Maybe it is a typo but may be not because you used the command "route -n".

If you realy want some help you should post config files! It is easier to track problems.

By,
michael

-- 
Thorsten Göllner

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40237 Düsseldorf


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