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Understanding Underlay Management

A private cloud data center is a critical business infrastructure that enterprise customers and service providers need. These private cloud data centers help deliver automated application networking services to internal departments. Today, most enterprises and service providers are moving from a vendor proprietary fabric to a standard-based EVPN-VXLAN data center built on IP Clos technology. In an EVPN-VXLAN data center, the underlay network is the physical infrastructure (switches, routers, firewall) on which overlay network services are built.

An EVPN-VXLAN data center fabric relies on a standard model that consists of tenants. These tenants are a group of endpoints, where,

  • groups are subnets that are routed to other groups.

  • endpoints are bridged within a group.

  • tenants are routed to other tenants depending on the overlay architecture.

  • tenants, groups, and endpoints may have services such as security, transit, multihoming, and QoS associated with them.

  • tenants and groups are implemented in the network as IP and Ethernet Virtual Private Networks (VPNs) and Virtual Tunnel End Points (VTEPs).

EVPN-VXLAN is used in a data center fabric to deliver multi-tenant networking services. The following network virtualization overlay architectures can be deployed in an EVPN-VXLAN IP fabric.

  • Centrally-Routed Bridging overlay design—inter-VN routing occurs in either the spine switch or border leaf switch.

  • Edge-Routed Bridging overlay design— inter-VN routing occurs natively in the leaf switch that workloads and servers are attached to.

  • Ethernet overlays—Layer 2 reachability and workload mobility across endpoints are the main services that the data center fabric provides.

  • IP overlay—traffic in a tenant is routed using IP routes.

Contrail Networking Release 5.0.1 supports the automation and management of EVPN-VXLAN data center IP fabric as well as the automation of layer 2 and layer 3 multi-tenant services on the IP fabric. The existing Contrail Networking configuration node can provide intent driven automation capabilities on physical network elements such as ToR and EoR switches, Spines, SDN gateway, and VPN gateways in the data center. In addition, you can perform basic device management functions such as image upgrade, device discovery, device underlay configuration, assigning roles to devices, and viewing node profile information from the node.

Benefits of Underlay Management

  • Enables basic device management functions from the Contrail Networking configuration node.

  • Enables underlay network automation.

  • Supports zero-touch-provisioning (ZTP) of factory-default devices to form an IP Clos network.


    ZTP allows you to provision new devices in your network automatically, with minimal manual intervention.