Data Center Interconnect

Contrail Networking supports the automation of data center interconnect (DCI) of two different data centers.

These topics provide information on data center interconnect deployment topologies and how you can create a data center interconnect.

Understanding Data Center Interconnect

You can automate data center interconnect (DCI) of two different data centers. Multiple tenants connected to a logical router in a data center can exchange routes with tenants connected to a logical router in another data center. All BGP routers in a data center should peer with local route reflectors and not with BGP routers on another fabric. Contrail Networking Release 5.1 supports interconnect of data centers that exist in different fabrics. Contrail Networking defines elements (spine switch and leaf switch) that belong to a data center.

A single Contrail Networking cluster can manage multiple data center pods that are composed of two-tier IP fabric. These data center pods are used to provision overlay layer 2 and layer 3 networking services as virtual networks and logical routers.

Contrail Networking automates the interconnection of logical routers (Layer 3 VRF) in each pod. A DCI object represents the extension of a logical router from one data center pod to another by using EVPN VXLAN Type 5 routes. These logical routers that are extended to the devices in each fabric are assigned DCI-Gateway role. The routing policies are configured on both pods to ensure EVPN type 5 routes are exchanged across the data center. For more information, see Creating Data Center Interconnect.

Note:

The gateway devices must support DCI-Gateway routing bridging role.

Data Center Interconnect Deployment Topologies

Contrail Networking supports the following data center interconnect (DCI) deployment topologies.

DCI using EBGP
DCI using IBGP

DCI using EBGP

Figure 1: DCI using EBGP Connection

DCI using EBGP connection establishes an EBGP connection between two data centers. The data centers are configured with two different autonomous system (AS) numbers as depicted in Figure 1.

DCI using IBGP

Figure 2: DCI using IBGP Connection

DCI using IBGP connection establishes an IBGP connection between two data centers. The data centers are configured with the same autonomous system (AS) numbers as depicted in Figure 2.

Creating Data Center Interconnect

These topics provide step-by-step instructions to create data center interconnect.

Prerequisites

Before you start creating data center interconnect, ensure that:

Junos OS 18.1 or later is installed
Data center pods that Contrail Networking automates must have IP reachability
Logical routers and client virtual networks are connected
Logical routers extended to the devices in each fabric are assigned DCI-Gateway role
BGP sessions between loopback addresses are reachable
Underlay connectivity is enabled
There is a route reflector on each data center that Contrail Networking is peering to

Follow these steps to create a data center interconnect.

Create a Fabric
Create Virtual Network
Create Logical Routers
Create DCI

Create a Fabric

Follow these steps to create a fabric with brownfield devices from the Contrail Command user interface (UI):

Click Fabrics.
The Fabrics page is displayed.
Click Create.
You are prompted to select a provisioning option.
Click Existing Fabric to import existing (brownfield) devices by discovery.
Figure 3: Select Provisioning Option
Click Provision.
The Create Fabric page is displayed.

Figure 4: Create Fabric Page

Enter the following information:

Table 1: Provision Existing Fabric
Field		Action
Name		Enter a name for the fabric.
Username		Enter a username for the device.
Password		Enter a password for the device.
Overlay ASN (iBGP)		Enter autonomous system (AS) number in the range of 1-65,535. If you enable 4 Byte ASN in Global Config, you can enter 4-byte AS number in the range of 1-4,294,967,295.
Node profiles		Add node profiles. You can add more than one node profile. All preloaded node profiles are added to the fabric by default. You can remove a node profile by clicking X on the node profile.
Management subnets		Enter the following information: CIDR—Enter CIDR network address. Gateway—Enter gateway address. Note: You enter the CIDR address range in the Management subnets field to search for devices. Any device that has a previously configured management IP on the subnet is discovered.
Underlay ASNs (eBGP)		Enter autonomous system (AS) number in the range of 1-65,535. If you enable 4 Byte ASN in Global Config, you can enter 4-byte AS number in the range of 1-4,294,967,295. Enter minimum value in ASN From field. Enter maximum value in ASN To field.
Fabric subnets (CIDR)		Enter fabric CIDR address. Note: Fabric subnets are used to assign IP addresses to interfaces that connect to leaf or spine devices.
Loopback subnets (CIDR)		Enter loopback address. Note: Loopback subnets are used to auto-assign loopback IP addresses to the fabric devices.

Click Next.
The Discovered devices page is displayed.

The Device discovery progress bar on the Discovered devices page displays the progress of the device discovery job.

Figure 5: Device Discovery Progress Bar

The list of devices discovered are listed in the Discovered devices page.
Select the device(s) you want to add to the fabric and then click Add.
The device is added to the fabric.
Click Next to assign roles.
The Assign to devices page is displayed.
Click the Assign icon at the end of the row to assign roles.
The Assign role to devices pop-up is displayed.
Assign physical roles and routing bridging roles.
For Spine Devices:
- Select spine from the Physical Role list.
- Select DCI-Gateway from the Routing Bridging Roles list.
  
  Figure 6: Assign Role to Spine Devices
For Leaf Devices:
- Select leaf from the Physical Role list.
- Select DCI-Gateway from the Routing Bridging Roles list.
  
  Figure 7: Assign Role to Leaf Devices
Click Assign to confirm selection and then click Autoconfigure to initiate the auto-configuration job.
The Autoconfigure page is displayed.

Create Virtual Network

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

Click Overlay>Virtual Networks.
The All Networks page is displayed.
Click Create to create a network.
The Create Virtual Network page is displayed.

Figure 8: Create Virtual Network Page
Enter a name for the network in the Name field.
Select network policies from the Network Policies list. You can select more than one network policy.
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.
The VXLAN ID is populated by default and is displayed in the VxLAN Network Identifier field.
Enter valid IPv4 subnet or mask in the CIDR field.
Enter valid IPv4 address in the Gateway field.
Click Create.
The All Networks page is displayed. The virtual networks that you created are displayed in this page.

Create Logical Routers

Follow these steps to create a logical router (LR).

Click Overlay>Logical Routers.
The Logical Routers page is displayed.
Click Create.
The Create Logical Router page is displayed.

Enter the following information.

Field	Action
Name	Enter a name for the Logical Router.
Admin State	Select Up.
Extend to Physical Router	Select the routers from the list.
Logical Router Type	Select VXLAN Routing from the list.
Connected Networks	Select the networks from the list.
Public Logical Router	(Optional) Select this check box if you want the logical router to function as a public logical router.
VxLAN Network Identifier	Enter VXLAN network identifier. Range: 1 through 16,777,215
Route Target(s)	Click +Add to add route targets. Enter Autonomous System (AS) number in the ASN field. Enter ASN in the range of 1-4,294,967,295, when 4 Byte ASN is enabled in Global Config. Enter ASN in the range of 1-65,535, when 4 Byte ASN is disabled. You can also add suffix L or l (lower-case L) at the end of a value in the ASN field to assign an AS number in 4-byte range. Even if the value provided in the ASN field is in the range of 1-65,535, adding L or l (lower-case L) at the end of the value assigns the AS number in 4-byte range. If you assign the ASN field a value in the 4-byte range, you must enter a value in the range of 0-65,535 in the Target field. Enter route target in the Target field. Enter route target in the range of 0-65,535, when 4 Byte ASN is enabled and ASN field is assigned a 4-byte value. Enter route target in the range of 0-4,294,967,295, when the ASN field is assigned a 2-byte value.

Click Create to create the logical router.
The Logical Routers page is displayed.
Repeat Step 3 and Step 4 to create another logical router.

Create DCI

Creating Data Center Interconnect

Follow these steps to create a DCI of two different data centers from the Contrail Command user interface (UI).

Click Overlay > DCI.
The DCI page is displayed.
Click Create.
The Create DCI page is displayed.

Figure 9: Create DCI Page