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 11:12:26PM +0200, Mark Schneider wrote:
> 
>    Tested and *nonworking* working OSes (no IP address):
>    - CentOS 6.0
> 
> 
>    Pings from *centos-hvm* to dom0 interface*no ip-traffic on peth0*

This is just like it should be. When you ping dom0 packets obviously should not 
go out.

> 
>    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
>    19:45:30.283679 IP 192.168.1.180 > 192.168.1.124: ICMP echo request, id
>    61445, seq 23, length 64
>    19:45:31.285560 IP 192.168.1.180 > 192.168.1.124: ICMP echo request, id
>    61445, seq 24, length 64
> 

And here on the bridge you see traffic, so that's ok.


>    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.


-- Pasi


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