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.

[Mark Schneider <ms@xxxxxxxxxxxxxxxxxxxxxx>]

Am 16.08.2011 09:43, schrieb Pasi Kärkkäinen:
> On Tue, Aug 16, 2011 at 01:16:18AM +0200, Mark Schneider wrote:
>    
> > Am 16.08.2011 00:57, schrieb Mark Schneider:
> >      
> > > Am 16.08.2011 00:23, schrieb Pasi Kärkkäinen:
> > >        
> > > > 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 ?
> > > >          
> > > No. It is plane wheezy with 3.0.1 kernel
> > >
> > >        
> and "iptables -L -n -v" does not list any rules?
>    
root@xen411dom0:~# iptables -L -n -v
Chain INPUT (policy ACCEPT 232 packets, 25984 bytes)
 pkts bytes target     prot opt in     out     source               
destination
Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               
destination
    0     0 ACCEPT     all  --  *      *       0.0.0.0/0            
0.0.0.0/0            PHYSDEV match --physdev-in peth0
Chain OUTPUT (policy ACCEPT 184 packets, 24528 bytes)
 pkts bytes target     prot opt in     out     source               
destination
root@xen411dom0:~#

> > Trace inside HVM (s. default gateway: 192.168.1.1 is-at 00:1d:7e:ad:35:a8)
> > # ---------------------------
> > [root@centoshvm ~]# tcpdump -i eth0 -nn | tee /tmp/tcpdum-eth0.txt
> > tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> > listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
> > 01:05:31.996278 IP 192.168.1.180.22>  192.168.1.124.40173: Flags [P.],
> > seq 1128465923:1128466115, ack 1021543041, win 135, options [nop,nop,TS
> > val 1036128 ecr 3459996], length 192
> > 01:05:31.998526 IP 192.168.1.124.40173>  192.168.1.180.22: Flags [.],
> > ack 192, win 176, options [nop,nop,TS val 3460006 ecr 1036128], length 0
> > 01:05:55.401107 ARP, Request who-has 192.168.1.1 tell 192.168.1.180,
> > length 28
> > 01:05:55.402608 ARP, Reply 192.168.1.1 is-at 00:1d:7e:ad:35:a8, length 46
> > 01:05:55.402681 IP 192.168.1.180>  192.168.1.1: ICMP echo request, id
> > 5894, seq 1, length 64
> > 01:05:56.399192 IP 192.168.1.180>  192.168.1.1: ICMP echo request, id
> >      
> So the HVM domU gets the correct MAC of the gateway,
> and starts sending packets to it.
>
> The next step would be to dump on eth0 on dom0.. do you see the same packets 
> there?
>
> At the same time also dump on peth0, do the packets go out there to the 
> physical network?
>    
# Requests and reply on peth0 are there:
18:06:00.324825 ARP, Request who-has 192.168.1.1 tell 192.168.1.180, 
length 28
18:06:00.325012 ARP, Reply 192.168.1.1 is-at 00:1d:7e:ad:35:a8, length 46

# Requests and reply on eth0 are *also* there:
18:06:00.324825 ARP, Request who-has 192.168.1.1 tell 192.168.1.180, 
length 28
18:06:00.325012 ARP, Reply 192.168.1.1 is-at 00:1d:7e:ad:35:a8, length 46

# There are ICMP requests on eth0 but look like that there are *not 
forwarded* to peth0.
18:06:00.334350 IP 192.168.1.180 > 192.168.1.1: ICMP echo request, id 
55045, seq 1, length 64
18:06:01.324098 IP 192.168.1.180 > 192.168.1.1: ICMP echo request, id 
55045, seq 2, length 64
Any idea why? I have attached both tpcdumps.

I use the same dom0 domain for other HVMs like squeeze, wheezy or 
OpenSolaris and the work as expected.
Thank you / regards, Mark

--
ms@xxxxxxxxxxxxxxxxxxxxxx

Attachment: tcpdump-dom0-eth0.txt.gz
Description: application/gzip

Attachment: tcpdump-dom0-peth0.txt.gz
Description: application/gzip

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