I''m trying to get DHCP working with DomU clients. I don''t want
to use
libvirtd. There''s a dhcpd on the machine and it works fine for all
clients
in the network, but not for DomUs. If I set a static IP on the DomU all
networking for them is fine, so there''s no general networking problem.
I use the xen 3.2 packages for CentOS on CentOS 5.1.
There was a public IP address on eth0 and a private IP address on eth0:0.
I changed that around after I discovered with tcpdump that dhcpd was
replying on eth0 like publicip.bootps -> privateip.bootpc. This
isn''t a
problem for all other packets, but apparently for DHCP.
Bridging is setup with the standard Xen 3.2 network-bridge script by xend
like this:
bridge name bridge id STP enabled interfaces
eth0 8000.000c6e101f84 no vif3.0
vif2.0
vif1.0
peth0
Once I had the private IP address on eth0 and not on the alias anymore
DHCP started working on DomUs. However, I had to discover it worked only
for this first bootup and not later on. The DomU starts up, gets an IP
assigned and is happy. However, when it comes to renew the lease it hits
the same problem as before. There''s first DHCPREQUEST, no answer, then
DHCPDISCOVER, no answer, it eventually falls back to pinging the gateway
(which works) and then stops. Eventually it drops it''s own IP.
Sometimes it starts working after a reboot of the host, sometimes not.
Actually, there''s not "no answer", it''s just that
the reply doesn''t make
it to the DomU. tcpdump shows the reply on peth0, but not on eth0.
Here''s
an example from peth0:
15:59:41.964744 IP (tos 0x10, ttl 16, id 0, offset 0, flags [none],
proto: UDP (17), length: 328) 0.0.0.0.bootpc > 255.255.255.255.bootps:
BOOTP/DHCP, Request from 00:16:3e:43:17:01 (oui Unknown), length: 300,
xid:0x4e682b4f, secs:50, flags: [none] (0x0000)
Client Ethernet Address: 00:16:3e:43:17:01 (oui Unknown)
[|bootp]
15:59:41.965540 IP (tos 0x10, ttl 16, id 0, offset 0, flags [none],
proto: UDP (17), length: 328) mambo.bolera.lan.bootps >
192.168.1.149.bootpc: BOOTP/DHCP, Reply, length: 300, xid:0x4e682b4f,
secs:50, flags: [none] (0x0000)
Your IP: 192.168.1.149
Client Ethernet Address: 00:16:3e:43:17:01 (oui Unknown)
[|bootp]
eth0 sees only the first packet. So, there is something necessary to make
the DHCP packet travel from peth0 to eth0. I tried several routing and ip
tables commands, nothing helps.
What is necessary to make DHCP in DomUs work?
Kai
--
Kai Schätzl, Berlin, Germany
Get your web at Conactive Internet Services: http://www.conactive.com
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Kai Schaetzl wrote:> > I''m trying to get DHCP working with DomU clients. I don''t want to use > libvirtd. There''s a dhcpd on the machine and it works fine for all clients > in the network, but not for DomUs. If I set a static IP on the DomU all > networking for them is fine, so there''s no general networking problem. > > I use the xen 3.2 packages for CentOS on CentOS 5.1. > > There was a public IP address on eth0 and a private IP address on eth0:0. > I changed that around after I discovered with tcpdump that dhcpd was > replying on eth0 like publicip.bootps -> privateip.bootpc. This isn''t a > problem for all other packets, but apparently for DHCP. > > Bridging is setup with the standard Xen 3.2 network-bridge script by xend > like this: > > bridge name bridge id STP enabled interfaces > eth0 8000.000c6e101f84 no vif3.0 > vif2.0 > vif1.0 > peth0 > > Once I had the private IP address on eth0 and not on the alias anymore > DHCP started working on DomUs. However, I had to discover it worked only > for this first bootup and not later on. The DomU starts up, gets an IP > assigned and is happy. However, when it comes to renew the lease it hits > the same problem as before. There''s first DHCPREQUEST, no answer, then > DHCPDISCOVER, no answer, it eventually falls back to pinging the gateway > (which works) and then stops. Eventually it drops it''s own IP. > Sometimes it starts working after a reboot of the host, sometimes not. > Actually, there''s not "no answer", it''s just that the reply doesn''t make > it to the DomU. tcpdump shows the reply on peth0, but not on eth0. Here''s > an example from peth0: > > 15:59:41.964744 IP (tos 0x10, ttl 16, id 0, offset 0, flags [none], > proto: UDP (17), length: 328) 0.0.0.0.bootpc > > 255.255.255.255.bootps: > BOOTP/DHCP, Request from 00:16:3e:43:17:01 (oui Unknown), > length: 300, > xid:0x4e682b4f, secs:50, flags: [none] (0x0000) > Client Ethernet Address: 00:16:3e:43:17:01 (oui Unknown) > [|bootp] > 15:59:41.965540 IP (tos 0x10, ttl 16, id 0, offset 0, flags [none], > proto: UDP (17), length: 328) mambo.bolera.lan.bootps > > 192.168.1.149.bootpc: BOOTP/DHCP, Reply, length: 300, xid:0x4e682b4f, > secs:50, flags: [none] (0x0000) > Your IP: 192.168.1.149 > Client Ethernet Address: 00:16:3e:43:17:01 (oui Unknown) > [|bootp] > > eth0 sees only the first packet. So, there is something necessary to make > the DHCP packet travel from peth0 to eth0. I tried several routing and ip > tables commands, nothing helps. > > What is necessary to make DHCP in DomUs work?Gee, Kai, you''ve had the worse problems with your Xen setup. What happens if you disable the eth0:0 alias temporarily? -Ross ______________________________________________________________________ This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution or copying of this e-mail, and any attachments thereto, is strictly prohibited. If you have received this e-mail in error, please immediately notify the sender and permanently delete the original and any copy or printout thereof. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Ross S. W. Walker wrote on Fri, 4 Apr 2008 13:42:18 -0400:> Gee, Kai, you''ve had the worse problems with your Xen setup.at least concerning DHCP :-(> > What happens if you disable the eth0:0 alias temporarily?No change at all. As I don''t really need DHCP for the installed machines I will go with static addresses now. The acquiring of IP during a PXE installation works fine and there is where I really may need it. Kai -- Kai Schätzl, Berlin, Germany Get your web at Conactive Internet Services: http://www.conactive.com _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Just out of curiosity, what happens if you move the dchp service to a different machine on your network? I run quite a few domUs on various servers and have never had an issue like this... however, my dhcp service is hosted on a server that does not run xen. It provides NFS/SMB storage, PXE, DHCP and DNS for my test lan... I''ve never tried getting domUs to pull an address from a DHCP service on the Xen server before... On Sun, Apr 6, 2008 at 10:31 AM, Kai Schaetzl <maillists@conactive.com> wrote:> Ross S. W. Walker wrote on Fri, 4 Apr 2008 13:42:18 -0400: > > > > Gee, Kai, you''ve had the worse problems with your Xen setup. > > at least concerning DHCP :-( > > > > > > What happens if you disable the eth0:0 alias temporarily? > > No change at all. As I don''t really need DHCP for the installed machines I > will go with static addresses now. The acquiring of IP during a PXE > installation works fine and there is where I really may need it. > > > Kai > > -- > Kai Schätzl, Berlin, Germany > Get your web at Conactive Internet Services: http://www.conactive.com > > > > > _______________________________________________ > > > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users >-- ------------------> Jeffrey Lane - W4KDH <------------------- www.jefflane.org Another cog in the great Corporate Wheel The internet has no government, no constitution, no laws, no rights, no police, no courts. Don''t talk about fairness or innocence, and don''t talk about what should be done. Instead, talk about what is being done and what will be done by the amorphous unreachable undefinable blob called "the internet user base." -Paul Vixie _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Kai Schaetzl wrote:> I''m trying to get DHCP working with DomU clients. I don''t want to use > libvirtd. There''s a dhcpd on the machine and it works fine for all clients > in the network, but not for DomUs. If I set a static IP on the DomU all > networking for them is fine, so there''s no general networking problem.Hi Kai, I used to have EXACTLY that problem (and others) until I added "post-up ethtool -K eth0 tx off" to the interface stanzas in /etc/network/interfaces of the domU:s like this: auto eth0 iface eth0 inet dhcp post-up ethtool -K eth0 tx off Good luck! /Martin Leben _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Martin Leben wrote on Tue, 08 Apr 2008 19:21:12 +0200:> post-up ethtool -K eth0 tx offI saw this suggestions already several times. ethtool -k eth0 shows that all checksumming is already off. So, this is not an option that could help here :-( Thanks, anyway. Kai -- Kai Schätzl, Berlin, Germany Get your web at Conactive Internet Services: http://www.conactive.com _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Kai Schaetzl wrote:> Martin Leben wrote on Tue, 08 Apr 2008 19:21:12 +0200: > > >> post-up ethtool -K eth0 tx off >> > > I saw this suggestions already several times. ethtool -k eth0 shows that > all checksumming is already off. So, this is not an option that could help > here :-( Thanks, anyway. > > Kai >In both directions? (I have read that if the transmit does not work then try the receive). Doug _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Jeff Lane wrote on Tue, 8 Apr 2008 09:25:32 -0400:> Just out of curiosity, what happens if you move the dchp service to a > different machine on your network?Funny that you ask. I had thought about that but not yet tried. I run quite a few domUs on various> servers and have never had an issue like this... however, my dhcp > service is hosted on a server that does not run xen.I switched off dhcpd and switched on the DHCP server on a win2k3 machine. I verified with a Windows client that it works. No go with the DomUs. Then I tried the dhcpd on my gateway appliance. Works. Then I restarted dhcpd on the Xen machine and there it works as well and is still working. Let''s see how long it lasts. Kai -- Kai Schätzl, Berlin, Germany Get your web at Conactive Internet Services: http://www.conactive.com _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Doug Breshears wrote on Tue, 08 Apr 2008 16:36:01 -0700:> In both directions? (I have read that if the transmit does not work then > try the receive).All is off by default, I think there are no such features in this chipset as I cannot switch it on. Offload parameters for eth0: Cannot get device rx csum settings: Operation not supported Cannot get device udp large send offload settings: Operation not supported rx-checksumming: off tx-checksumming: off scatter-gather: off tcp segmentation offload: off udp fragmentation offload: off generic segmentation offload: off It still works at the moment. Kai -- Kai Schätzl, Berlin, Germany Get your web at Conactive Internet Services: http://www.conactive.com _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users