[Xen-users] Xen Networking problem!

Stéphane Cesbron
Fri, 01 Aug 2008 08:32:01 -0000

Hi,

I ''ve got a CentOS 5.2 server running xen 3.0 with 2 DomUs also running
CentOS 5.2.
All my boxes are up-to date.

I''m experiencing trouble with networking.
Dom0 can reach the outside world when no DomU are started. It can also
reach the outside world when only one DomU is running.
The troubles begin when I start the second DomU. At first, this new
DomU, called DomU2, can''t get outside. (at the time Dom0 and DomU1 are
still reachable from outside).
Once I get connected to DomU2 (console mode, xm console DomU2) and try
to get outside, I''ll get through after a small amout of time.
Nevertheless, this causes Dom0 to stop being reachable from the outside.
Therefore when my two DomUs are running, there are running fine and I
can reach them with SSH but Dom0 becomes unreachable. After sometimes it
changes Dom0 becomes reachable again and one of the 2 DomUs becomes
unreachable from the outside. It is completely random but there''s still
one of the Doms which is unreachable. It depends on the one I''m
connected to !
BUT being connected to the console on the server, I can reach each DomU
(DomU1 and DomU2) from Dom0 or reach Dom0 from each DomUs (DomU1 and DomU2)
I help myself with some tutorials but can''t get through my
difficulties.
http://wiki.xensource.com/xenwiki/XenNetworking
http://doc.fedora-fr.org/wiki/Xen_et_le_réseau
http://www.shorewall.net/XenMyWay.html  => Xen and the Art of Consolidation

Nevertheless, I can''t get through my troubles.

Here''s the result of the ifconfig command when everything is started :
DomUs + Dom0
eth0      Link encap:Ethernet  HWaddr 00:21:85:32:CA:8E
          inet adr:172.20.25.2  Bcast:172.20.25.255  Masque:255.255.255.0
          adr inet6: fe80::221:85ff:fe32:ca8e/64 Scope:Lien
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:88446 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2906 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 lg file transmission:0
          RX bytes:6888620 (6.5 MiB)  TX bytes:189520 (185.0 KiB)

lo        Link encap:Boucle locale
          inet adr:127.0.0.1  Masque:255.0.0.0
          adr inet6: ::1/128 Scope:HÃ´te
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:34 errors:0 dropped:0 overruns:0 frame:0
          TX packets:34 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 lg file transmission:0
          RX bytes:7010 (6.8 KiB)  TX bytes:7010 (6.8 KiB)

peth0     Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
          adr inet6: fe80::fcff:ffff:feff:ffff/64 Scope:Lien
          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
          RX packets:25871448 errors:0 dropped:0 overruns:0 frame:0
          TX packets:5396663 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 lg file transmission:100
          RX bytes:31027675382 (28.8 GiB)  TX bytes:434789497 (414.6 MiB)
          MÃ©moire:de340000-de360000

vif0.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
          adr inet6: fe80::fcff:ffff:feff:ffff/64 Scope:Lien
          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
          RX packets:2906 errors:0 dropped:0 overruns:0 frame:0
          TX packets:88446 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 lg file transmission:0
          RX bytes:189520 (185.0 KiB)  TX bytes:6888620 (6.5 MiB)

vif1.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
          adr inet6: fe80::fcff:ffff:feff:ffff/64 Scope:Lien
          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
          RX packets:1886 errors:0 dropped:0 overruns:0 frame:0
          TX packets:86964 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 lg file transmission:32
          RX bytes:127848 (124.8 KiB)  TX bytes:6453003 (6.1 MiB)

vif2.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
          adr inet6: fe80::fcff:ffff:feff:ffff/64 Scope:Lien
          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
          RX packets:5389130 errors:0 dropped:0 overruns:0 frame:0
          TX packets:10150353 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 lg file transmission:32
          RX bytes:358810111 (342.1 MiB)  TX bytes:15229333872 (14.1 GiB)

virbr0    Link encap:Ethernet  HWaddr 00:00:00:00:00:00
          inet adr:192.168.122.1  Bcast:192.168.122.255
Masque:255.255.255.0
          adr inet6: fe80::200:ff:fe00:0/64 Scope:Lien
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:44 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 lg file transmission:0
          RX bytes:0 (0.0 b)  TX bytes:8758 (8.5 KiB)

xenbr0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
          RX packets:84790 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 lg file transmission:0
          RX bytes:4982000 (4.7 MiB)  TX bytes:0 (0.0 b)

I can''t understand why the MAC addresses of peth0 is different from the
one of eth0. vibr0 seems to be useless. These should be the same,
shouldn''t they ?
peth0''s MAC address and xenbr0''s MAC address are the same
which seems
logical to me. Am I wrong ?

Can anyone help ?
Any suggestions will be greatly appreciated.

Kind regards,