Create Virtual Network

date_range 07-Jun-23

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A virtual network is a collection of endpoints, such as virtual machine instances, that can communicate with each other. You can also connect virtual networks to your on-premises network. A virtual network in a EVPN VXLAN data center corresponds to a bridge domain for one tenant in a multi-tenant data center fabric.

Follow these steps to create a virtual network from the Contrail Command user interface (UI).

Navigate to Overlay>Virtual Networks.
The All Networks page is displayed.
Click Create to create a network.
The Create Virtual Network page is displayed.
Enter a name for the network in the Name field.
Select VN Fabric Type.
Select Routed to enable routed virtual network functionality. A routed virtual network represents a layer 3 subnet between the fabric (border gateway) and the third-party physical network device. For more information, see Using Static, eBGP, PIM, and OSPF Protocols to Connect to Third-Party Network Devices.

Select Switched (default option) for tenant virtual network on leaf, bare metal server, or vRouter.
Select network policies from the Network Policies list. You can select more than one network policy.
Network policies provide connectivity between virtual networks by allowing or denying specified traffic. They define the access control lists to virtual networks. To create a new network policy, navigate to Overlay>Network Policies.

For more information on creating network policies, see Create Network Policy.

Note:
You can attach a network policy to the virtual network after you have created the virtual network.
Select any one of the following preferred allocation mode.
- Flat subnet only
- Flat subnet preferred
- (Default) User defined subnet only
- User defined subnet preferred
An allocation mode indicates how you choose a subnet. You select Flat subnet only or Flat subnet preferred allocation mode when the subnet is shared by multiple virtual networks. However, you select (Default) User defined subnet only or User defined subnet preferred allocation mode when you want to define a subnet range.

Enter subnet information as given in Table 1.

Table 1: Subnet Information
Field	Action
Network IPAM	Select the IP address management method that controls IP address allocation, DNS, and DHCP for the subnet.
CIDR	Enter the overlay subnet CIDR.
Allocation Pools	Enter a list of ranges of IP addresses for vRouter-specific allocation.
Gateway	Enter the gateway IP address of the overlay subnet. This field is disabled by default. To configure this field, uncheck Auto Gateway.
Service Address	Specify the user configured IP address for DNS Service instead of the default system allocated one.
Auto Gateway	This check box is enabled by default and gateway address is allocated by the system. When this box is unchecked, gateway address is user configurable.
DHCP	Select this check box if you want Contrail to provide DHCP service.
DNS	Select this check box if you want the vRouter agent to provide DNS service.

Enter host route information.
Host routes are a list of prefixes and next hops that are passed to the virtual machine through DHCP.
1. Route Prefix—Enter a full CIDR value with an IP address and a subnet mask. For example, 10.0.0.0/24.
2. Next Hop—Enter next hop address.
Enter floating IP pool information.
A floating IP address is an IP address (typically public) that can be dynamically assigned to a running virtual instance. You can configure floating IP address pools in project networks, then allocate floating IP addresses from the pool to virtual machine instances in other virtual networks.
1. Pool Name—Enter pool name.
2. Projects—Select project from the list.

Enter fat flows information. See Table 2.

You can apply fat flows to all VMIs under the configured VN. Fat flows help reduce the number of flows that are handled by Contrail.

Table 2: Configure Fat Flow
Field		Action
Protocol		Select the application protocol.
Port		Enter a value between 0 through 65,535. Enter 0 to ignore both source and destination port numbers. Note: If you select ICMP as the protocol, the Port field is not enabled.
Ignore Address		Configure fat flows to support aggregation of multiple flows into a single flow by ignoring source and destination ports or IP addresses. If you select Destination, only the Prefix Aggregation Source fields are enabled. If you select Source, only the Prefix Aggregation Destination fields are enabled. If you select the None (selected by default), both Prefix Aggregation Source and Prefix Aggregation Destination fields are enabled.
Prefix Aggregation Source	Source Subnet	Enter the source IP address. Ensure that the source subnet of the flows match. For example, enter 10.1.0.0/24 to create fat flows with 10.1.0.0/24 as the subnet. The valid subnet mask range is /8 through /32. Note: For packets from the local virtual machine, source refers to the source IP of the packet. For packets from the physical interface, source refers to the destination IP of the packet.
Prefix Aggregation Source	Prefix	Enter source subnet prefix length. The prefix length you enter is used to aggregate flows matching the source subnet. For example, when the source subnet is 10.1.0.0/16 and prefix length is 24, the flows matching the source subnet is aggregated to 10.1.x.0/24 flows. The valid the prefix length range is /(subnet mask of the source subnet) through /32.
Prefix Aggregation Destination	Destination Subnet	Enter the destination IP address. Ensure that the destination subnet of the flows match. Enter 10.1.0.0/24 to create fat flows with 10.1.0.0/24 as the subnet. The valid subnet mask range is /8 through /32. Note: For packets from the local virtual machine, destination refers to the destination IP of the packet. For packets from the physical interface, destination refers to the source IP of the packet.
Prefix Aggregation Destination	Prefix	Enter the destination subnet prefix length. The prefix length you enter is used to aggregate flows matching the destination subnet. For example, when the source subnet is 10.1.0.0/16 and prefix length is 24, the flows matching the source subnet is aggregated to 10.1.x.0/24 flows. The valid prefix length range is /(subnet mask of the destination subnet) through /32.

Enter routing policy and bridge domain information as given below.

Select routing policy from the Routing Policies list.

To create a routing policy, navigate to Overlay>Routing>Routing Policy.
Define a list of route target prefixes.

Enter an IP address in the ASN field and Target in the range 0 through 65,535, or ASN in the range 1 through 65,535 and Target in the range 1 through 4,294,967,295 if 4-byte ASN is disabled. If 4-byte ASN is enabled, enter ASN in the range 1 through 4,294,967,295 and Target in the range 0 through 65,535.
Define export route targets.

You can advertise the matched routes from the local virtual routing and forwarding (VRF) table to the MPLS routing table.

Enter an IP address in the ASN field and Target in the range 0 through 65,535, or ASN in the range 1 through 65,535 and Target in the range 1 through 4,294,967,295 if 4-byte ASN is disabled. If 4-byte ASN is enabled, enter ASN in the range 1 through 4,294,967,295 and Target in the range 0 through 65,535.
Define import route targets.

Import the matched routes from the MPLS routing table and to the local virtual routing and forwarding (VRF) table.

Enter an IP address in the ASN field and Target in the range 0 through 65,535, or ASN in the range 1 through 65,535 and Target in the range 1 through 4,294,967,295 if 4-byte ASN is disabled. If 4-byte ASN is enabled, enter ASN in the range 1 through 4,294,967,295 and Target in the range 0 through 65,535.

Enter bridge domain information. See Table 3.

A bridge domain is a set of logical interfaces that share the same flooding or broadcast characteristics.

Table 3: Bridge Domains
Field	Action
Name	Enter a name for the Layer 2 or Layer 3 bridge domain.
I-SID	Enter a Service Identifier in the range from 1 through 16777215.
MAC Learning	Enable or disable MAC learning. MAC learning is the process of obtaining the MAC addresses of all the nodes in a virtual network. It is enabled by default.
MAC Limit	Configure the maximum number of MAC addresses that can be learned.
MAC Move Limit	Configure the maximum number of times a MAC address move occurs in the MAC move time window. A MAC move is when a MAC address appears on a different physical interface or within a different unit of the same physical interface.
Time Window (secs)	Configure the period of time over which the MAC address move occurs. The default period is 10 seconds.
Aging Time (secs)	Configure the MAC table aging time, the maximum time that an entry can remain in the Ethernet Switching table before it is removed. The default time period is 300 seconds.

Enter advanced configuration information as given in Table 4.

Table 4: Advanced Configuration
Field		Action
Admin State		Select the administrative state of the virtual network.
Reverse Path Forwarding		Enable or disable Reverse Path Forwarding (RPF) check for the virtual network.
Shared		Select to share the virtual network with all tenants.
External		Select the check box to make the virtual networks reachable externally.
Allow Transit		Select to enable the transitive property for route imports.
Mirroring		Select to mark the virtual network as a mirror destination network.
Flood Unknown Unicast		Select to flood the network with packets with unknown unicast MAC address. By default, the packets are dropped.
Multiple Service Chains		Select to allow multiple service chains within two networks in a cluster.
IP Fabric Forwarding		Select to enable fabric based forwarding.
Forwarding Mode		Select the packet forwarding mode for the virtual network.
Extend to Physical Router(s)		Select the physical router to which you want to extend the logical router. The physical router provides routing capability to the logical router.
Static Route(s)		Select the static routes to be added to this virtual network.
QoS		Select the QoS to be used for this forwarding class.
Security Logging Object(s)		Select the security logging object configuration for specifying session logging criteria.
ECMP Hashing Fields		Configure one or more ECMP hashing fields. When configured all traffic destined to that VN will be subject to the customized hash field selection during forwarding over ECMP paths by vRouters.
PBB Encapsulation		Select to enable Provider Backbone Bridging (PBB) EVPN tunneling on the network.
PBB ETree		Select to enable PBB ETREE mode on the virtual network which allows L2 communication between two end points connected to the vRouters. When the check box is deselected, end point communication happens through an L3 gateway provisioned in the remote PE site.
Layer2 Control Word		Select to enable adding control word to the Layer 2 encapsulation.
SNAT		Select to provide connectivity to the underlay network by port mapping.
MAC Learning		Enable or disable MAC learning. MAC learning is the process of obtaining the MAC addresses of all the nodes in a virtual network. It is enabled by default.
Provider Network		Select the provider network. The provider network specifies VLAN tag and the physical network name.
IGMP enable		Enable or disable IGMP.
Multicast Policies		Select the multicast policies. To create a policy, navigate to Overlay>Multicast Policies.
Max Flows		Enter the maximum number of flows permitted on each virtual machine interface of the virtual network.

Click Create.
The All Networks page is displayed. The virtual network that you created is displayed on this page.

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