Connectivity Guide

Congure VLT
(Optional) To use VXLAN in a VLT domain, congure the VLT domain — including the VLT Interconnect (VLTi) interfaces, backup
heartbeat, and VLT MAC address — as described in Virtual link trunking.
Required VLT VXLAN conguration:
• The IP address of the VTEP source loopback interface must be same on the VLT peers.
• If you use a port-scoped VLAN to assign tagged access interfaces to a virtual network, you must congure a unique VLAN ID for the
VLT Interconnect (VLTi) link to identify trac belonging to each virtual network. Congure a VLAN to transmit VXLAN trac over the
VLTi link in VIRTUAL-NETWORK mode. All trac sent and received from a virtual network on the VLTi carries the VLTi VLAN ID tag.
Congure the same VLTi VLAN ID on both VLT peers. You cannot use the ID of an existing VLAN on a VLT peer or the reserved
untagged VLAN ID. You can use the VLTi VLAN ID to assign tagged or untagged access interfaces to a virtual network.
virtual-network vn-id
vlti-vlan vlan-id
Best practices:
• If a VLT peer loses connectivity to the underlay L3 network, it continues to transmit routing trac to the network through the VLTi link
on a dedicated L3 VLAN to the other VLT peer. It is best practice to congure a L3 VLAN between VLT peers in the underlay network
and enable routing on the VLAN; for example:
OS10(config)# interface vlan4000
OS10(config-if-vl-4000)# no shutdown
OS10(config-if-vl-4000)# ip address 41.1.1.1/24
OS10(config-if-vl-4000)# ip ospf 1 area 0.0.0.0
• To reduce trac loss when a VLT peer boots up and joins an existing VLT domain, or when the VLTi links fails and the VLT peer is still up
as detected by the VLT heartbeat, create an uplink state group. Congure all access VLT port channels on the peer as upstream links.
Congure all network-facing links as downstream link. For example:
OS10(config)# uplink-state-group 1
OS10(conf-uplink-state-group-1)# enable
OS10(conf-uplink-state-group-1)# downstream ethernet1/1/1-1/1/2
OS10(conf-uplink-state-group-1)# upstream port-channel 10
If the VLTi link fails and the peer is up, all access ports and network links are automatically brought down on the secondary VLT peer.
The secondary node is isolated to avoid trac loss for connected dual-homed hosts.
Monitor VXLAN
Use show commands to verify the VXLAN conguration and monitor VXLAN operation.
View VXLAN virtual network
OS10# show virtual-network
Virtual-Network: 1000
Members:
Vlan 100: ethernet1/1/1, ethernet1/1/2
Vlan 101: port-channel5
VXLAN Virtual Network Identifier : 10005
Codes : DP - MAC-learn Dataplane, CP - MAC-learn Controlplane, UUD - Unknown-Unicast-Drop
Source Interface: loopback1 (3.3.3.3)
Peers (flood-list): 10.10.10.10 (DP), 20.20.20.10 (DP, UUD)
View VXLAN virtual-network port
OS10# show virtual-network interface ethernet 1/1/1
Interface Vlan Virtual-network
ethernet1/1/1 100 1000
ethernet1/1/1 200 2000
ethernet1/1/1 300 3000
520
VXLAN