Overview of OTT DCI in an EVPN Network
About This Network Configuration Example
Use this Network Configuration Example (NCE) to deploy Layer 2 and or Layer 3 services between two or more data center fabric networks. We focus on the over-the-top (OTT) Data Center Interconnect (DCI) model. This NCE describes how to configure the interconnection. It does not provide the step-by-step procedure for configuring and deploying the EVPN VXLAN fabric in the data center. For a detailed configuration and more information on deploying an EVPN-VXLAN in a data center, see Detailed Configurations for the EVPN-VXLAN Network for the Data Centers and Data Center EVPN-VXLAN Fabric Architecture Guide.
Use Case Overview
DCI connects multiple data center fabrics. In most cases, data centers are geographically separated. In some cases, there are multiple fabrics within a data center. DCI can be used to provide overlay Layer 2 and Layer 3 services between these fabrics.
With OTT DCI, the control plane is extended across data center fabrics. The interconnected data center fabrics act as a single logical fabric. The unified control plane facilitates both Layer 2 and Layer 3 services. It is expected that IP connectivity has been established between the data center fabrics in the underlay. The WAN underlay can be a Layer 3 VPN from a third-party, dark fiber, IPSec over Internet, etc. With OTT DCI, the leaf devices require a full mesh of VXLAN tunnels with all other leaf devices in all data centers wherever the given VLAN is configured. Figure 1 illustrates a typical OTT DCI architecture.
Benefits of OTT DCI
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OTT DCI makes interconnecting data center simpler and can be deployed easily with QFX switches when you are expanding your existing data center infrastructure. Juniper recommends the following QFX series switches and roles for the deployment of OTT DCI:
QFX 10000 series and QFX 5120-32C switches in the spine Role
QFX5120-32C, QFX5120-48Y, and QFX5110 switches in the leaf role
Consider the following in your DCI deployment:
When Layer 2 services for VLANs are stretched across multiple data centers, you must have a full mesh of VXLAN tunnels among all the leaf devices in all the data centers where the VLAN is configured. As the number of leaf devices increases and the number of VLANs increases, you will start to see issues related to scaling.
You should limit OTT DCI deployment to small and medium-sized data centers. For large data centers, we recommend using VXLAN-to-VXLAN stitching.
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