Xen users - Jun 2009 - DHCP server on Dom-0: guests fail to connect

Hello all,

I am working on a Centos 5.2 installation using Xen 3.0, and trying to set
up a DHCP server on Domain-0 so as to assign a range of IP addresses to new
guests. I installed dhcp package on Dom-0 and here are contents of
dhcpd.conf file
(Dom-0 has eth0 - 128.6.237.10 and eth1 - 192.168.2.21 over crossover
cable):

==================================================ddns-update-style interim;
ignore client-updates;
authoritative;

subnet 128.6.237.0 netmask 255.255.255.0 {
host eth0     {
        hardware ethernet  00:21:9B:FC:D9:E9;
        fixed-address      128.6.237.10;
}
}
subnet 192.168.2.0 netmask 255.255.255.0 {
host eth1   {
        hardware ethernet  00:21:9B:FC:D9:EA;
        fixed-address      192.168.2.21;
}
}

# range of addresses to be assigned to new guests

subnet 192.168.1.0 netmask 255.255.255.0 {
# --- default gateway
        option routers                  192.168.1.1;
        option subnet-mask              255.255.255.0;
        option domain-name              "dw.vnet";
        option domain-name-servers      128.6.236.5, 128.6.224.114;

        option time-offset              -18000; # Eastern Standard Time
        range 192.168.1.128 192.168.1.254;
}
        default-lease-time 21600;
        max-lease-time 43200;

==============================================
/etc/init.d/dhcpd start
Starting DHCP  [OK]

Then I am trying to create a guest with config file:
===============================================name = "sw_cp_fed8"
maxmem = 512
memory = 512
vcpus = 4
bootloader = "/usr/bin/pygrub"
on_poweroff = "destroy"
on_reboot = "restart"
on_crash = "restart"
#vfb = [ "type=vnc,vncunused=1,keymap=en-us" ]
disk = [ "tap:aio:/var/lib/xen/images/sw_cp_fed8.img,xvda,w" ]
vif = ['''']
dhcp="dhcp"
===============================================
But the guest fails to start
Error:
TCP/IP error: VNC connection to hypervisor host got refused

/var/log/messages says:
================================================Jun  3 11:42:13 darkwing kernel:
tap tap-62-51712: 2 getting info
Jun  3 11:42:14 darkwing kernel: device vif62.0 entered promiscuous mode
Jun  3 11:42:14 darkwing kernel: ADDRCONF(NETDEV_UP): vif62.0: link is not
ready
Jun  3 11:42:14 darkwing kernel: blktap: ring-ref 8, event-channel 17,
protocol 1 (x86_64-abi)
Jun  3 11:42:25 darkwing kernel: virbr0: port 1(vif62.0) entering disabled
state
Jun  3 11:42:25 darkwing kernel: device vif62.0 left promiscuous mode
Jun  3 11:42:25 darkwing kernel: virbr0: port 1(vif62.0) entering disabled
state
===============================================
*I need to run about 10 Virtual machines allotted dynamic IPs from DHCP
server on Dom-0. Then I am seeking to stress test them on the machine, to
study performance isolation among guests.
Can anyone help and guide me? Am I on the right path?*


Thanks & Regards,
Siddharth Wagh
MS, Electrical & Computer Engineering
Rutgers University, NJ
Web: http://www.eden.rutgers.edu/~swagh/


_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

On Wed, Jun 3, 2009 at 11:03 PM, Siddharth Wagh
<siddharth.wagh@gmail.com> wrote:
> (Dom-0 has eth0 - 128.6.237.10 and eth1 - 192.168.2.21 over crossover
> cable):
>
> # range of addresses to be assigned to new guests
>
> subnet 192.168.1.0 netmask 255.255.255.0 {
does dom0 has an interface with 192.168.1.0/24 address? If not, that
block will be ignored by default.
> #vfb = [ "type=vnc,vncunused=1,keymap=en-us" ]
> But the guest fails to start
> Error:
> TCP/IP error: VNC connection to hypervisor host got refused
How did you start this guest?
Since you disable vfb line, it''s only normal that there won''t
be any
GUI console for that PV guest. This is not related to DHCP btw.

-- 
Fajar

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

On Thu, Jun 4, 2009 at 10:39 PM, Siddharth Wagh
<siddharth.wagh@gmail.com> wrote:
> vif = [ "mac=00:16:3e:3d:2c:fa,bridge=xenbr0" ]
> =====================================>
> 2. Then, I set out to remove their static addressing and assign the same
VMs
> new IPs using DHCP. So, I made following changes:
> a. Installed DHCP on Dom-0
> b. Changed dhcpd.conf file as given above (I am attempting to give range of
> private addresses to VMs, I am not sure how to connect them to Dom-0 or how
> to create interface on Dom-0 for same)
> c. Changed guest VM file as follows:
> =================================
> dhcp = "dhcp"
> vif = [ '''' ]
> CAN YOU TELL ME HOW DO I GO ABOUT HOW TO ASSIGN IPs TO GUEST VMs ON THE RUN
> AND NOT STATICALLY? THANKS A LOT FOR YOUR REPLY.
Your main problem is that you misunderstood how Xen networking works.
In short, when you use bridging (the default on most distros), you''ll
essentially have a domU that behaves just like any other machine on
the network. That means you don''t need to alter domU config. At all.
It wouldn''t matter as the OS on domU can change it anyway.

What you should do is you should return the domU config to the
original one, and learn how to setup DHCP properly. Since the bridge
is xenbr0, the process would be the same as setting DHCP server where
clients are connected to DHCP server''s eth0.

-- 
Fajar

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

On Tue, Jun 9, 2009 at 11:17 PM, Siddharth Wagh<siddharth.wagh@gmail.com>
wrote:
> Hello,
>
> Scrapping off DHCP, I am working on following NAT approach with static
> addresses to VMs...
> I did the following:
> 1. Changed xend-config.sxp file as:
> (network-type network-nat)
> (vif-script vif-nat)
Since you''re using Centos anyway, by default it has libvirtd which
does what you want by default. It creates virbr0, with address
192.168.122.0/24, using network-bridge script. So its NAT on top of
bridge. As a bonus, it also uses "builtin" dhcp and dns server for
domUs so you don''t have to worry about that. You simply use thye
default setting (network-bridge) and point your domU config to use
virbr0 bridge.

-- 
Fajar

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

On Thu, Jun 11, 2009 at 10:26 PM, Siddharth
Wagh<siddharth.wagh@gmail.com> wrote:
> Please pardon me for bothering you, but I tried to use virbr0 as you
> suggested but it doesnt seem to work. While creating guest using
> virt-manager, it gives me the option of using "peth0
(bridge:xenbr0)" as
> shared physical device (I am connected to Ethernet) and not virbr0. How do
I
> point to the virbr0 bridge then??
virt-manager on my system lets me choose "virtual network",
"default".
Don''t use shared physical device if you need to use virbr0.
As an alternative, you could also create domU config file manually
(something like
http://wiki.centos.org/HowTos/Xen/InstallingCentOSDomU) and tell it to
use virbr0.

-- 
Fajar

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users