Dell EMC SmartFabric OS10 User Guide Release 10.5.1

With asymmetric IRB routing, the virtual networks that you configure are present in all the VXLAN tunnel endpoints (VTEPs). If the DHCP server and client reside in different VRFs within the same or different VTEPs, request from the client does not reach the server.

In this scenario, the server network must be leaked to the client VRF for the client request to reach the server. The client network must be leaked to the server VRF for the server reply to reach the client.

In this example, the DHCP client is connected to GREEN VRF in VTEP1 and the server is connected to RED VRF in VTEP 2. The client is not able to reach the server. The client and server connected networks from the GREEN and RED VRFs must be leaked to the other tenant VRFs respectively. Route leaking enables server connectivity for hosts connected to different VRFs.

For VXLAN-related configurations, see Configure VXLAN. To configure route leaking between VRFs with asymmetric IRB routing:

VTEP1

1. Configure IP helper address specifying the DHCP server ip address in the client-connected virtual networks with the client-connected VRF name. For IPv6 DHCP helper address, specify the server VRF in the helper-address command.

   VTEP1(config)# interface virtual-network 10
   VTEP1(conf-if-vn-10)# ip helper-address 20.1.1.100 vrf GREEN

2. Configure loopback interfaces. Assign the loopback interfaces as source interfaces for the VRF.

   VTEP1(config)# interface loopback 2
   VTEP1(conf-if-lo-2)# ip vrf forwarding GREEN
   VTEP1(conf-if-lo-2)# ip address 51.1.1.1/32
   VTEP1(conf-if-lo-2)# exit
   
   VTEP1(config)# interface loopback 3
   VTEP1(conf-if-lo-3)# ip vrf forwarding RED
   VTEP1(conf-if-lo-3)# ip address 52.1.1.1/32
   VTEP1(conf-if-lo-3)# exit
   
   VTEP1(config)# ip vrf GREEN
   VTEP1(conf-vrf)# update-source-ip loopback 2
   VTEP1(conf-vrf)# exit
   
   VTEP1(config)# ip vrf RED
   VTEP1(conf-vrf)# update-source-ip loopback 3
   VTEP1(conf-vrf)# exit

3. Leak the server-connected networks to the tenant VRF to which the client is connected.

   VTEP1(config)# ip route vrf GREEN 20.1.1.0/24 interface virtual-network 20
   VTEP1(config)# ip route vrf GREEN 52.1.1.1/32 interface loopback 3

4. Leak the client-connected networks to the tenant VRF to which the server is connected.

   VTEP1(config)# ip route vrf RED 10.1.1.0/24 interface virtual-network 10
   VTEP1(config)# ip route vrf RED 51.1.1.1/32 interface loopback 2

VTEP2

1. Configure IP helper address specifying the DHCP server ip address in the client-connected virtual networks with the client-connected VRF name. For IPv6 DHCP helper address, specify the server VRF in the helper-address command.

   VTEP2(config)# interface virtual-network 10
   VTEP2(conf-if-vn-10)# ip helper-address 20.1.1.100 vrf GREEN

2. Configure loopback interfaces. Assign the loopback interfaces as source interfaces for the VRF.

   VTEP2(config)# interface loopback 2
   VTEP2(conf-if-lo-2)# ip vrf forwarding GREEN
   VTEP2(conf-if-lo-2)# ip address 51.1.1.2/32
   VTEP2(conf-if-lo-2)# exit
   
   VTEP2(config)# interface loopback 3
   VTEP2(conf-if-lo-3)# ip vrf forwarding RED
   VTEP2(conf-if-lo-3)# ip address 52.1.1.2/32
   VTEP2(conf-if-lo-3)# exit
   
   VTEP2(config)# ip vrf GREEN
   VTEP2(conf-vrf)# update-source-ip loopback 2
   VTEP2(conf-vrf)# exit
   
   VTEP2(config)# ip vrf RED
   VTEP2(conf-vrf)# update-source-ip loopback 3
   VTEP2(conf-vrf)# exit

3. Leak the server-connected networks to the tenant VRF to which the client is connected.

   VTEP2(config)# ip route vrf GREEN 20.1.1.0/24 interface virtual-network 20
   VTEP2(config)# ip route vrf GREEN 52.1.1.2/32 interface loopback 3

4. Leak the client-connected networks to the tenant VRF to which the server is connected.

   VTEP2(config)# ip route vrf RED 10.1.1.0/24 interface virtual-network 10
   VTEP2(config)# ip route vrf RED 51.1.1.2/32 interface loopback 2