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Instances alternative gateway / VLAN tags corresponding datacenter VLANs

asked 2014-04-23 22:01:10 -0500

LainesStack gravatar image

Hello All I have two questions regarding Neutron:

1) In the documentation I always see diagrams where the network traffic from all the instances is routed through the network node. For example here: (

Is it possible to configure a different gateway for the instances that the gateway is the real physical router and skip the way through the network node?

2) If there are VLANs created in the physical switches is it possible to create this VLANs also in the OpenStack/Neutron environment to match the datacenter VLANs?

Thank you!

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answered 2014-04-25 08:21:05 -0500

Your instances would need network connectivity to your physical router in layer 2. If using VLAN tenant networks (From question 2 I assume this is the case), you'd create provider networks with specific VLANs. These VLANs should be trunked by your switches, and known by the physical router.

For example: neutron net-create net1 --provider:network_type=vlan --provider:physical_network:physnet1 --provider:segmentation_id:100

  • physnet1 is the name of the physical network configured in plugin.ini of your controller and l2 agents. Make sure that physnet1 is then connected to a bridge that is then connected to the correct physical datacenter network, that the router is also connected to (Assuming OVS agents here)
  • segmentation_id of 100 in this case would mean that the new "net1" network would be a VLAN network with a VLAN tag of 100
  • You would then hook up your instances to this network
  • Make sure that VLAN 100 is being trunked by your physical switches
  • In the subnet configuration for "net1" configure your physical router as the gateway
  • In your router, configure a sub-interface for VLAN 100 and set it with the correct IP (Or the equivalent configuration if using L3 switches or whatnot)
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Asked: 2014-04-23 22:01:10 -0500

Seen: 223 times

Last updated: Apr 25 '14