Re: [Xen-users] Re: [Xen-devel] xen 4.1.2* dhcp issue/bug when installing/booting HVM domU domains (CentOS 6, unbuntu 11.04 server). Debian/OpenSolaris work fine.

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Mon, Aug 15, 2011 at 11:58:24PM +0200, Mark Schneider wrote:
>>    
>>>     Pings from *centos-hvm* to default gateway *no ip-traffic on peth0*
>>>
>>>      
>> So here's your problem. Your bridge in dom0 is NOT forwarding the packets 
>> out to peth0..
>>
>>
>>    
>>>     root@xen411dom0:/ftp/HVM# tcpdump  -i eth0 'icmp[icmptype] = icmp-echo 
>>> and
>>>     icmp[icmptype] != icmp-echoreply'
>>>     tcpdump: verbose output suppressed, use -v or -vv for full protocol 
>>> decode
>>>     listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
>>>     19:54:00.770442 IP 192.168.1.180>  192.168.1.1: ICMP echo request, id 
>>> 518,
>>>     seq 23, length 64
>>>     19:54:01.770958 IP 192.168.1.180>  192.168.1.1: ICMP echo request, id 
>>> 518,
>>>     seq 24, length 64
>>>      
>> So where are these packets going to ? They're not getting out of dom0..
>>
>> Do you have a firewall rule in dom0 that drops them?
>>
>> Try these:
>> - In the HVM guest: run "arp -an" and check what MAC address you see for the 
>> gateway-IP.
>> - In dom0: run "brctl showmacs eth0" and verify which port has the MAC of 
>> the gateway.
>>    
> [root@centoshvm ~]# arp -an
> ? (192.168.1.102) auf 00:1c:25:7e:fb:b7 [ether] auf eth0
> ? (192.168.1.124) auf b4:99:ba:c1:27:36 [ether] auf eth0
>

So the HVM guest has NOT received a MAC address for the gateway.. 
so ARP requests are not working from the HVM guest.

Do this:
- Shutdown the VM.
- Start the VM.
- Run tcpdump in dom0 (tcpdump -i tap<x> -nn)
- Try pinging the gateway from the HVM guest.
- Paste the whole tcpdump output here.


>
> root@xen411dom0:~# brctl showmacs eth0
> port no mac addr                is local?       ageing timer
>   6     00:16:3e:27:17:67       no                 3.22
>   3     00:16:3e:27:20:67       no                40.85
>   1     00:1c:25:7e:fb:b7       no                 0.00
>   1     00:1d:7e:ad:35:a8       no                12.66
>   1     b4:99:ba:c1:27:36       yes                0.00
>   2     fe:ff:ff:ff:ff:ff       yes                0.00
> root@xen411dom0:~# arp -an
> ? (192.168.1.102) auf 00:1c:25:7e:fb:b7 [ether] auf eth0
> ? (192.168.1.180) auf 00:16:3e:27:17:67 [ether] auf eth0
> ? (192.168.1.1) auf 00:1d:7e:ad:35:a8 [ether] auf eth0
>

Are you running some firewall (iptables or ebtables) in dom0 ? 


-- Pasi


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