Dell EMC SmartFabric OS10 User Guide Release 10.5.1

With symmetric IRB routing, the virtual networks to which the hosts are connected might be disjoint or stretched virtual networks. A disjoint virtual network does not span across VTEPs whereas a stretched virtual network spans across VTEPs.

In this example, the virtual networks are disjoint.

• VTEP1 has virtual network 10 configured in tenant VRF GREEN.
• VTEP2 has virtual network 20 configured in tenant VRF RED.
• The client is connected to virtual network 10 in VTEP1.
• The server is connected to virtual network 20 in VTEP2.

In this case, request from the client does not reach the server as they are part of different tenant VRFs. Connected route leaking cannot be configured in VTEP1 because the server-connected network is not present in VTEP1. The server-connected network must be leaked to the client VRF in VTEP2. This leaked route must be advertised as EVPN type-5 route in the client VRF to VTEP1.

For VXLAN-related configurations, see Configure VXLAN. To configure route leaking between VRFs with symmetric 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
   VTEP1(conf-if-vn-10)# exit

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 client-connected networks to the tenant VRF to which the client is connected.

   VTEP1(config)# ip route vrf RED 10.1.1.0/24 interface virtual-network 10
   VTEP1(config)# ip route vrf RED 51.1.1.2/32 interface loopback 2

4. Advertise the client network-leaked routes through EVPN type-5 routes to the server-connected VRF.

   VTEP1(config)# evpn
   VTEP1(config-evpn)# vrf RED
   VTEP1(config-evpn-vrf-RED)# advertise ipv4 static
   VTEP1(config-evpn-vrf-RED)# advertise ipv4 connected
   VTEP1(config-evpn-vrf-RED)# exit
   VTEP1(config-evpn)# exit

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 51.1.1.1/32
   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 52.1.1.1/32
   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. Advertise the client network-leaked routes through EVPN type-5 routes to the client-connected VRF.

   VTEP2(config)# evpn
   VTEP2(config-evpn)# vrf GREEN
   VTEP2(config-evpn-vrf-GREEN)# advertise ipv4 static
   VTEP2(config-evpn-vrf-GREEN)# advertise ipv4 connected
   VTEP2(config-evpn-vrf-GREEN)# exit
   VTEP2(config-evpn)# exit