{"id":614,"date":"2016-01-09T22:42:18","date_gmt":"2016-01-09T21:42:18","guid":{"rendered":"http:\/\/www.opencloudblog.com\/?p=614"},"modified":"2021-01-17T14:48:11","modified_gmt":"2021-01-17T13:48:11","slug":"openstack-juno-neutron-deployment-part-2-network-infrastructure","status":"publish","type":"post","link":"https:\/\/www.opencloudblog.com\/?p=614","title":{"rendered":"OpenStack Liberty Neutron Deployment (Part 2 Network Infrastructure)"},"content":{"rendered":"

The physical network<\/h1>\n

A cloud needs an „physical“ network using real „switching routers“ to transport data between the physical nodes.<\/p>\n

The physical network has the following layout:<\/p>\n

\"Physical<\/a>

Physical set up<\/p><\/div>\n

Each floating pool is implemented using one vlan on the physical network infrastructure. Each flat network requires also one vlan on the physical network. VXLAN requires also one vlan on the physical network.<\/p>\n

VXLAN adds additional headers (IP and UDP) to packets. You must increase the mtu of the transport VXLAN vlan to a higher value, let’s take 1600. Do not follow the „recommendations“ to reduce the MTU of VMs using the DHCP server. Such a „recommendation“ only leads to big problems in a production environment — do not use a reduced MTU<\/strong>!<\/p>\n

The configuration of the physical switching router could be (using a pseudo config language):<\/p>\n

vlan 100 name Floating-Pool-1\nvlan 101 name Floating-Pool-2\nvlan 200 name Flat-Net-1\nvlan 201 name Flat-Net-2\n# set the mtu to 1600 for vlan 4000\nvlan 4000 name vxlan mtu 1600\n# do not use vlan 1 for untagged packets\nvlan 4090 name native vlan\n#\n############\n#\ninterface vlan 100\n  description Floating-Network-1\n  ip address 198.18.0.1\/20\ninterface vlan 101\n  description Floating-Network-2\n  ip address 198.18.16.1\/20\ninterface vlan 200\n  description Flat-Network-1\n  ip address 198.19.1.1\/24\ninterface vlan 201\n  description Flat-Network-2\n  ip address 198.19.2.1\/24\n# a L3 interface for the vxlan vlan may be added\n#\n#############\n#\n# the ports to the nodes (network and compute)\n# They use the same config !\n# just one link to each node - multiple links using LACP may also be used\ninterface port1\n  description to-network-node\n  mode trunk\n  trunk native vlan 4090\n  trunk vlan 100,101,200,201,4000,4090\n  mtu 1600\ninterface port2\n  description to-compute-node\n  mode trunk\n  trunk native vlan 4090\n  trunk vlan 100,101,200,201,4000,4090\n  mtu 1600<\/pre>\n
The network set up of the nodes<\/h1>\n
The basic network set up of compute and network nodes is exactly the same. On the nodes, a basic network configuration of the Operating system must be provided by the user. This configuration connects the transport network for VMs on the nodes to the physical network. The network setup of a node is shown in the drawing below:<\/p>\n
\"Openvswitch<\/a>
Openvswitch Bridges on the Nodes<\/p><\/div>\n
The cool part of the network setup is, that only ONE physical interface (or a LACP bundle) is used to transport VM traffic. This interface is connected to br-uplink. If you read the Openstack manuals and believe in everything which is written there, you would end up using FOUR physical interfaces:<\/p>\n