Problem sending email, sometimes have to restart the network service...?

[willy85]

Dear all,

I am having a trouble at sending email with zimbra, sometimes I have to restart the network service (using service network restart syntax, FYI I am using CentOS 5.1). The SMTP Server I am using is the SMTP server provided by my ISP.

And when the emails are deferred, I tried to telnet the ISP SMTP Server and it ended with failure. After I restart the network service, I can normally telnet the SMTP server again. And when I check to zimbra admin interface, the error status in the deferred mail item view is network connection timed out. Is the problem is in my network card or the connection to the SMTP server or something else...?

Do anyone here have experienced the same problem like me?

Thanks in advance

[uxbod]

Is this on a physical server or VM ? When this happens can you still ping your gateway ? Is the default route still in place ? You can check with

netstat -rn

[willy85]

This server is on VM (XEN) and I can't ping the gateway. This problem causing all the mails to be deferred and it's kinda weird because i didn't realize this before. Only this virtual server which the network service need to be restarted. Do you know something or two about this? Please help. Thanks.

[uxbod]

Would you happen to have a Cisco firewall in front of your server ? Are you setting a MAC address within your Dom-U config ? eg.

vif = [ 'mac=00:16:3e:c6:e3:47,ip=192.168.1.100,bridge=eth0' ]

[willy85]

Euh... What's that? Where supposed I set that? :|
Actually the VM server wasn't built by me, it's already there when I maintain this network.... So, I'm still quite blind about XEN, eventhough I have experience using VMware. Can you please guide me or give a me a good link for learning XEN? Thanks, uxbod

[uxbod]

On the physical server you should have /etc/xen. If you have root access to the Dom-0 then you can type

xm list

which will show you all the Dom-U's. Go into /etc/xen, once you have identified your VM, and then look at the file with the same name. A good place to start as always is Welcome to xen.org, home of the Xen® hypervisor, the powerful open source industry standard for virtualization.. I had a similar issue when I first setup Xen and the problem was the ARP table on my firewall ended up with two IPs bound to the same MAC address! When I disabled Proxy ARP the problem went away.

[willy85]

Thank you very much for the help, uxbod. I'll try your advice right away