Re: [Xen-users] Strange Networking Issue

[Jonathon Jones <xen@xxxxxxxxxx>]

In the domU....

[root@secure network-scripts]# ip addr list
1: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 00:16:3e:3d:20:f0 brd ff:ff:ff:ff:ff:ff
    inet 75.126.154.240/22 brd 75.126.155.255 scope global eth0
    inet 75.126.154.241/22 brd 75.126.155.255 scope global secondary eth0:0
    inet 75.126.154.242/22 brd 75.126.155.255 scope global secondary eth0:1
    inet 75.126.154.243/22 brd 75.126.155.255 scope global secondary eth0:2
    inet6 fe80::216:3eff:fe3d:20f0/64 scope link
       valid_lft forever preferred_lft forever
3: sit0: <NOARP> mtu 1480 qdisc noop
    link/sit 0.0.0.0 brd 0.0.0.0

You can see that all IP's are added in the same way yet only .240 is pingable.  I can add the IP manually to dom0 and get it to ping so I'm thinking there is some bug in this latest version of xen.  Does anybody else have any other conclusion?

Jon

Jonathon Jones wrote:

Thanks so much for your response.

Martin Hierling wrote:

Hi,

instead of eth0 or somehow my bridge is screwed up.  If I remove .242
below from the domU and add it to the dom0 it begins to work just fine.
I'm still trying to figure out how .241 is working fine from the domU
when it is a secondary IP and no other secondary IP's work from the domU.

Are you sure nobody else uses the ip by accident? Whats the mac address from 242? (arp -n). Is that the mac from your DomU.

Yes, I'm quite certain since I can swap the IP back and forth between the dom0 and domU at will and it always will work on the dom0 but not in the domU.  Using arp -n doesn't show me anything that seems usable.  The following is the output from arp -n.  It is the same in both the dom0 and domU except that the Iface changes from eth1 to eth0 when going from dom0 to domU.

[root@secure network-scripts]# arp -n
Address                  HWtype  HWaddress           Flags Mask            Iface
75.126.153.177           ether   00:1A:30:38:90:00   C                     eth0

Does anybody know if the public IP has to be on eth0 in dom0 for
bridging to work properly?

Public IP has to be on the interface where the public net is! Are eth0 and eth1 in different VLANs?

Right, the public IP is on eth1 in dom0.  Which is how the provider set it up  Everything seems to work fine in this setup other than adding secondary IP's to domU's.  Yes, in the dom0, eth0 is on 10.10.16.2/26 vlan while eth1 is on public IP xxx.xxx.153.178/29

It looks like your provider set up another IP network for Dom0 and DomU. Are they on the same Layer 2 Network?

Well, my provider isn't aware of my xen setup.  They just gave me .153.178 and .154.240-.247 as usable IP's with a gateway of .153.177.

I dont know the exact setup of sour provider but the 2 networks you have are not fitting together.

Gateway: xxx.xxx.153.177
dom0: xxx.xxx.153.178 (on eth1, eth0 is assigned a 10.x.x.x IP.  This is
how my provider set it up)

dom1: xxx.xxx.154.240 (domU primary IP)
          xxx.xxx.154.241
          xxx.xxx.154.242

dom2: xxx.xxx.154.244 (domU primary IP)
          xxx.xxx.154.245
          xxx.xxx.154.246
 

Do you route or bridge? With bridge you need a netmask of 255.255.252.0 to reach the gateway from your DomUs.
So, you have to route the 154.240/29 network to your DomUs.

Martin

It is bridge.  I am not a networking guru or even a xen guru but i have been using xen for some time now and have set up several servers with it.  This is the first I have run into this type of situation.  The domU's do have a netmask of 255.255.252.0 so that they can reach the gateway and the primary IP I assign to eth0 in the domU works just fine every time.

How do I go about routing the 154.240/29 network to my domU's beyond what I have already done?  And why is it that the primary IP works fine and then strangely .241 works also but no other IP's do?  The inconsistency is nagging at me.

Thanks again for your help.  I am trying to migrate servers from one provider to another and this is holding me up.

Jon

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

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