Understanding Underlay Management
IN THIS SECTION
Benets of Underlay Management | 3
A private cloud data center is a crical business infrastructure that enterprise customers and service
providers need. These private cloud data centers help deliver automated applicaon 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,
rewall) 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, mulhoming, 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 mul-tenant networking services. The following
network virtualizaon overlay architectures can be deployed in an EVPN-VXLAN IP fabric.
• Centrally-Routed Bridging overlay design—inter-VN roung occurs in either the spine switch or
border leaf switch.
• Edge-Routed Bridging overlay design— inter-VN roung occurs navely in the leaf switch that
workloads and servers are aached to.
• Ethernet overlays—Layer 2 reachability and workload mobility across endpoints are the main services
that the data center fabric provides.
• IP overlay—trac in a tenant is routed using IP routes.
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