Openstack support multi tenant networks. That means two tenants may use the same network space. There must be some other way to isolate the networks of different tenants. So every network in Openstack is assigned a special segmentation id. In case of gre the segmentation id is the tunnel id. In case of vlan mode the segmentation id becomes the vlan id. I have some more detailed information in the below posts
http://fosskb.wordpress.com/2014/06/10/managing-openstack-internaldataexternal-network-in-one-interface/ http://fosskb.wordpress.com/2014/06/19/l2-connectivity-in-openstack-using-openvswitch-mechanism-driver/ On Thu, Jun 19, 2014 at 5:12 PM, <[email protected]> wrote: > Hi All, > > > > What is the requirement of GRE tunneling in openstack ? Why the VMs have > to communicate only through GRE tunnels ? > > > > > > Thanks > > Kumar > > ------------------------------ > > This message is for the designated recipient only and may contain > privileged, proprietary, or otherwise confidential information. If you have > received it in error, please notify the sender immediately and delete the > original. Any other use of the e-mail by you is prohibited. Where allowed > by local law, electronic communications with Accenture and its affiliates, > including e-mail and instant messaging (including content), may be scanned > by our systems for the purposes of information security and assessment of > internal compliance with Accenture policy. > > ______________________________________________________________________________________ > > www.accenture.com > > _______________________________________________ > Mailing list: > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack > Post to : [email protected] > Unsubscribe : > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack > >
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