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VXLAN Scenario
VXLAN tunnel stays down even if the remote VTEP IP is reachable through a recursive route. Following section explains the
scenario through an example configuration.
The following illustration depicts the topology in which the VTEPs are connected.
Figure 158. VXLAN Scenario
In the above illustration, R1 and R2 are the VTEPs that are trying to form the VXLAN tunnel. R3, the route reflector, exchanges
the routes across two IBGP peers (R1 and R2). Also, the R3 connects the R1 and R2 through a default route.
Following is the output of show ip routecommand for the above connection:
DellEMC# show ip route
Destination Gateway Dist/Metric Last Change
----------- ----- ----------- -----------
*B IN 0.0.0.0/0 via 192.168.11.2 200/0 16:13:30
C 1.1.1.1/32 Direct, Lo 1 0/0 8:59:34
B IN 2.2.2.2/32 via 192.168.22.1 200/0 00:36:48
From the above routing table it is understood that the remote VTEP 2.2.2.2/32 is resolved through next-hop 192.168.22.1, which
is not directly connected. This route is considered as a recursive route and there is no other route matching the next-hop except
the default 0.0.0.0/0. If the recursive lookup ends in a default route, the route is considered to be an unsuccessful recursion.
The VXLAN tunnel stays down even though the remote VTEP IP is reachable through a recursive route. As a workaround, make
sure to advertise the underlying routes from the route-reflector, so that the recursive lookup succeeds.
Routing in and out of VXLAN tunnels
VXLAN provides a way to extend a VLAN over a Layer3 tunnel (VXLAN tunnel) across data centers.
This functionality can also be extended one step further by enabling routing from a VLAN on one data center to a different
VLAN on another data center. This scheme to route in and out of tunnels (RIOT) requires setting up of hardware VTEPs that
are capable of routing over a VXLAN tunnel using a physical loopback configuration.
Physical Loopback for VXLAN RIOT
The following topology shows how VXLAN RIOT can be achieved using physical loopbacks. Two port-channels, vxlan and
non-vxlan loopback port-channel, are created in the device. Interface connected at one end of the physical loopback cable
is/are added as member of the non-vxlan loopback port-channel (P2/P6) and other end interfaces as a member of vxlan
loopback port-channel (P3/P7).
Virtual Extensible LAN (VXLAN)
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