Vxlan Layer 2 Gateway - Cisco Nexus 7000 Series Configuration Manual

VXLAN Layer 2 Gateway

VXLAN Layer 2 Gateway
The VXLAN Layer 2 gateway bridges traffic between physical servers and VM's behind vSwitches that are
in the same VNI.
• Connectivity of vSwitches to Cisco Nexus 7000 is via a Layer 2 port through a VLAN which is called
• Traffic from the physical server is mapped to segment (VNI) using VSI configuration.
• Traffic from VMs behind vSwitches are encapsulated in VXLAN format with VNI information from
• For packets coming from vSwitches, the Layer 2 VXLAN gateway strips the VXLAN header and
• VXLAN uses the control multicast group for broadcast, unknown unicast and multicast (BUM) traffic.
VXLAN Layer 3 Gateway
Layer 3 VXLAN gateway enables routing between different VNIs. The Cisco Nexus 7000 can be placed as
a pure Layer 3 routing box, which does inter VNI routing or it can be placed along with Layer 2 VXLAN
gateway functionality. To enable Layer 3 VXLAN functionality, BDI has to be configured on the tenant VNI
and the tenant VRF has to be different from the core VRF.
Cisco Nexus 7000 Series NX-OS VXLAN Configuration Guide
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a hypervisor VLAN. One of the requirements for a VXLAN gateway is that the hypervisor VLAN should
be Layer 3 enabled (SVI configured) and be a member of the core VRF.
the server to which it belongs. The VNI identifies the bridge-domain that both the physical server and
the virtual servers are a part.
identifies the bridge-domain before bridging the packet to the physical server. Similarly, when physical
servers talk to VM's behind vSwitches, the VXLAN header is appended with appropriate VNI information
before sending it to the vSwitches.
When the control multicast group is configured on the vSwitch, it sends IGMP reports to the Cisco
Nexus 7000 switch on the hypervisor VLAN . This results in Layer 2 multicast state creation for the
control multicast group on the hypervisor VLAN. Since the hypervisor VLAN is Layer 3 enabled on
the core VRF, it triggers a PIM join and Layer 3 multicast state creation. Thus, BUM traffic is bridged
to locally connected vSwitches via Layer 2 multicast bridging and to remote vSwitches behind Layer 3
cloud via Layer 3 multicast routing.
Configuring VXLAN Flood and Learn