• Anycast VXLAN L2 gateway
• All-active multihoming VXLAN L2 gateway
Single Homing VXLAN L2 GW
Consider a topology of single homing L2 gateway between DC and WAN. In this topology, ASR 9000 router
is the DCI PE router. The L2 gateway on the PE is a bridge which forwards L2 frames between VXLAN DC
and MPLS WAN. DC fabric devices, such as leaf and spine nodes, do not run IP multicast protocols, such as
PIM-SM. All L2 BUM traffic between Nexus 9000 router and ASR 9000 router is forwarded through ingress
replication at VXLAN imposition node.
Figure 81: Single Homing VXLAN L2 GW
A tenant VNI is enabled on all the four Nexus 9000 leaf nodes and one ASR 9000 border leaf node for L2VPN
service. An IP host in DC1 initiates a communication to another IP host in DC2. The first ARP request goes
from DC1 to DC2. Nexus 9000 router receives the ARP first, and uses ingress replication approach to flood
the frame to other leaf nodes in DC1. One copy arrives on border leaf node ASR 9000. ASR 9000 performs
L2 gateway operation. It replicates traffic using per EVI replication list at MPLS WAN side. One copy is sent
to DC2. The other to DC3.
In the reverse direction, when an IP host in DC2 initiates a communication with an IP host in DC1, an ARP
request arrives at ASR 9000 DCI PE from WAN. ASR 9000 performs L2 gateway operation using per VNI
ingress replication list for VXLAN. A total of four copies are created. Each copy is sent to one Nexus 9000
leaf node. Nexus 9000 leaf nodes that are configured as DFs forward the traffic to IP hosts on VMs.
L2VPN and Ethernet Services Configuration Guide for Cisco ASR 9000 Series Routers, IOS XR Release 6.3.x
558
EVPN Features
Single Homing VXLAN L2 GW
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