Users Guide

● View the hardware resources available for overlay routing in different profiles; for example, in the S5200-ON series:
OS10# show hardware overlay-routing-profile mode all
Mode Overlay Next-hop Underlay Next-hop Overlay L3 RIF
Underlay L3 RIF
Entries Entries Entries Entries
default-overlay-routing 8192 57344 2048
14336
disable-overlay-routing 0 65536 0
16384
balanced-overlay-routing 32768 32768 8192
8192
scaled-overlay-routing 53248 12288 12288 4096
● View the currently configured overlay routing profile; for example, in the S5200-ON series:
show hardware overlay-routing-profile mode
Overlay Underlay Overlay Underlay
Setting Mode Next-hop Next-hop L3 RIF L3 RIF
Entries Entries Entries Entries
Current default-overlay-routing 8192 57344 2048 14336
Next-boot default-overlay-routing 8192 57344 2048 14336
DHCP relay on VTEPs
Dynamic Host Configuration Protocol (DHCP) clients on hosts in the overlay communicate with a DHCP server using a DHCP
relay on the VTEP switch. To work seamlessly, VTEP DHCP relay transmits the virtual-network IP address of the relay interface
to the DHCP server.
By default, DHCP uses the giaddr packet field to carry these addresses to the server. In a VxLAN, which has overlay and
underlay subnets in the same default VRF, DHCP relay on VTEPs operates without user intervention. However, in a VXLAN in
which the underlay and overlay are in different VRFs, the default DHCP method is not successful. The IP tenant subnet is in the
overlay address space. The IP address where the VTEP is reachable is in the underlay address space. To transmit the IP subnet
of the client separately from the IP address where the VTEP is reachable, you must configure an additional DHCP sub-option (5
or 151) in DHCP relay agent option 82.
Because OS10 does not support the required sub-options in DHCP relay agent option 82, the giaddr packet field must contain
the virtual-network IP address of the relay interface, and this IP address must be reachable from the DHCP server in the
underlay. Each VTEP that acts as a DHCP relay must have its virtual-network IP address installed using a route leaking
mechanism as a route to the underlay and advertised to all underlay routers, including the spine switches.
Similarly, the DHCP server in the underlay VRF must be reachable from the client tenant VRF in the overlay. Configure a static
route for the DHCP server subnet in the underlay default VRF, and leak the static route to the client tenant VRF in the overlay.
This configuration sets up a bi-directional communication between the client and DHCP server across the virtual networks. The
route-leaking configuration is not required if the VxLAN overlay subnet and underlay subnet are in same default VRF.
Configure DHCP relay on VTEPs
1. Configure the IP address of the virtual-network relay interface in the non-default tenant VRF as a static route in the default
VRF.
OS10(config)# ip route 10.10.0.2/32 interface virtual-network 10
2. Configure a static IP route to the DHCP server interface in the tenant VRF.
OS10(config)# ip route vrf tenant01 40.1.1.0/24 interface vlan40
3. Configure DHCP relay on the virtual-network interface of the tenant VRF.
OS10(config)# interface virtual-network 10
OS10(conf-if-vn-10)# ip helper-address 40.1.1.1 vrf tenant01
View VXLAN configuration
Use show commands to verify the VXLAN configuration and monitor VXLAN operation.
VXLAN
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