[openstack-dev] [Neutron] VM could not get IP from dhcp server

康敬亭 jingting at unitedstack.com
Thu Mar 3 08:42:06 UTC 2016

Hi Michal

Thanks for your reply.

I think it's not the problem of scurity group rule, as comparing the working environment. 

The vxlan tunnel works correctly, and the packet sent from vm have arrived at network node, meanwhile we catch it on physical NIC, but do not catch it on vxlan port.

Maybe It's the problem of linux stack or vxlan driver? However, I checked vxlan driver was install correctly. 

Anyone have idea how to debug? Thanks!
Best regards,
------------------ Original ------------------
From:  "Ptacek, MichalX"<michalx.ptacek at intel.com>;
Date:  Thu, Mar 3, 2016 03:14 PM
To:  "OpenStack Development Mailing List (not for usage questions)"<openstack-dev at lists.openstack.org>; 

Subject:  Re: [openstack-dev] [Neutron] VM could not get IP from dhcp server

Hi Jingting,
just few general hints (probably already checked):
-          security group rules in openstack (check both igress, egress, ….) – it’s quite common that after deployment it’s have to be modified
-          Iptables / fw ? – check if some packets are dropped 
-          Cross-check if vlan is properly configured on physical interfaces
-          If you use tunnels, ensure that both IP’s are on bridges not on ported NIC’s
Best regards,
From: 康敬亭 [mailto:jingting at unitedstack.com] 
 Sent: Thursday, March 03, 2016 4:20 AM
 To: openstack-dev <openstack-dev at lists.openstack.org>
 Subject: [openstack-dev] [Neutron] VM could not get IP from dhcp server
Hi guys:
I have openstack Liberty(linuxbridge + vxlan) installed, and the vm could not get IP from dhcp server. 
Using tcpdump can get dhcp discover packet on physical NIC on network node, but can't get it on vxlan port(vxlan-100) on network node.
In opposite direction, Sending arp broadcast  in dhcp namespace, and we can get packet on vxlan port(vxlan-100) but can't get packet on physical NIC.
However, we find port 8472 is being listened. Meanwhile all interfaces(vxlan-100, physical NIC) are up and running.
What could be the reason for the issue? Any comments are appreciated.
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