[Xen-users] Troubleshooting Bridging

Adam Carheden
Tue, 06 Dec 2005 02:13:28 -0000

I can''t seem to get dhcp to work for DOMU with bridging like
it''s supposed
to in the tutorials. Does anyone have a good step-by-step troubleshooting
guide?

Here''s my setup:

DOM0: SuSE 9.3, firewall disabled
DOMU: gentoo 2005.1
DOMU: SuSE 9.3

In dom0, I run the following:
/etc/xen/scripts/network start
iptables -P FORWARD ACCEPT

Then I start my two domains. If I assign them static IP''s, everything
works
fine, but DHCP requests never get a resposne. I have tried it with and
without dhcp="dhcp" in the config file.

`tcpdump -i  xen-br0 -lenx -s 1500 | dhcpdump` or `tcpdump -i  eth0 -lenx -s
1500 | dhcpdump`  clearly shows a DHCPREQUEST from the mac address I''ve
assigned to my domu, but I never get a dhcpreply.

Everthing looks okay in DOM0 as far as I can tell (see below). What else
should I check?

dom0:/etc/xen # iptables --list
Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination
ACCEPT     all  --  anywhere             anywhere            PHYSDEV match
--physdev-in eth0

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
dom0:/etc/xen # brctl show
bridge name     bridge id               STP enabled     interfaces
xen-br0         8000.00105aac4561       no              eth0
                                                        vif7.0
                                                        vif8.0
dom0:/etc/xen # ifconfig -a
eth0      Link encap:Ethernet  HWaddr 00:10:5A:AC:45:61
          inet addr:192.168.109.26  Bcast:192.168.109.255  Mask:
255.255.254.0
          inet6 addr: fe80::210:5aff:feac:4561/64 Scope:Link
          UP BROADCAST NOTRAILERS RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:53322 errors:0 dropped:0 overruns:0 frame:0
          TX packets:34477 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:53151039 (50.6 Mb)  TX bytes:4320684 (4.1 Mb)
          Interrupt:9 Base address:0x1000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:13705 errors:0 dropped:0 overruns:0 frame:0
          TX packets:13705 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:1004429 (980.8 Kb)  TX bytes:1004429 (980.8 Kb)

sit0      Link encap:IPv6-in-IPv4
          NOARP  MTU:1480  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

vif7.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
          inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:420 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

vif8.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
          inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:411 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

xen-br0   Link encap:Ethernet  HWaddr 00:10:5A:AC:45:61
          inet addr:192.168.109.26  Bcast:192.168.109.255  Mask:
255.255.255.255
          inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:52126 errors:0 dropped:0 overruns:0 frame:0
          TX packets:33778 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:52281788 (49.8 Mb)  TX bytes:4217308 (4.0 Mb)

Any hints?