Deployment Guide

Example: Centralized Layer3 gateway routing
In earlier section, the VTEPs were configured in Distributed Gateway topology, where each VTEP can perform VxLAN Routing and any
routing decision will be taken by the ingress VTEP. There may be environments where some of the VTEPs have only Layer 2 VxLAN
capability and can perform only Layer 2 functionality. In this scenario, the VxLAN routing for these Layer 2 VTEPs can be centralized to
one or more Layer 3 VTEP, which support Layer 3 VxLAN functionality. The Layer 2 VxLAN capable VTEPs can be connected with the
centralized Layer 3 gateway either directly or through an IP underlay fabric. Any Routing traffic that is ingressing in a Layer 2 VTEP will be
switched to the Layer 3 centralized gateway and all routing decisions are taken in this centralized gateway and the traffic is sent to the
destination Layer 2 VTEP.
The following VXLAN example also uses a Clos leaf-spine topology.In this example, the VTEP 1 and VTEP 2 VLT pair are L2 gateway and
VTEP 3 and VTEP 4 VLT pair are a centralized L3 gateway. The hosts Host A and Host B are connected to the L2 gateway. The L2
gateway is connected to a centralized L3 gateway through an IP underlay fabric. The IP address and Anycast IP address have to be
configured for the virtual networks in the centralized L3 gateway alone and need not be configured in the L2 gateways.
Routing for the client-originated Layer3 traffic does not happen at the Layer2 VTEPs. These VTEPs are layer2 VTEPs and they forward
traffic to a centralized gateway. This gateway is the Layer3 gateway that routes traffic from one Layer2 segment to another.
Guidelines
If both Distributed routing and Centralized routing co-exist in the same environment, then a separate Gateway MAC need to be used for
the Centralized GW which is different from the common distributed GW MAC shared by all VTEPs.
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