Deployment Guide

ManualsBrandsDell ManualsAccess PlatformsPowerSwitch S3048-ON

16 Dell EMC Networking Virtualization Overlay with BGP EVPN

4.3 BGP EVPN VXLAN overlay

Rack n

R740xd-1

R740xd-2

R740xd-3

R740xd-4

ECMP

Gateway/

Firewall

S5248F-1a S5248F-1b

S4148U-2a S4148U-2b

S4148U-3a S4148U-3b

VNI 1614

172.16.14.253

172.16.15.253

172.16.14.253

172.16.15.253

172.16.16.253

VTEP

10.222.222.1

Border leafs

eBGP

Rack 1 Rack 2

VNI 1614

VNI 1616

VRF tenant1

VLTi

VLT

Z9264F-1 Z9264F-2

VLTVLT

VM VMVM

VMVM VM

Physical L3 connection

Physical L2 connection

Virtual L2 connection

VM on VNI 1614, IP 172.16.14.x /24

VM on VNI 1615, IP 172.16.15.x /24

VM on VNI 1616, IP 172.16.16.x /24

172.16.15.253

172.16.16.253

Anycast gateway - VNI 1614

Anycast gateway - VNI 1615

Indirect gateway - VNI 1616

172.16.14.253

VNI 1615

VTEP

10.222.222.2

VTEP

10.222.222.3

BGP EVPN topology with anycast gateways and an indirect gateway

In this deployment example, three VNIs are used: 1614, 1615, and 1616. All VNIs are configured all on six

leaf switches. However, only VNIs 1614 and 1615 are configured with anycast gateways. Because these VNIs

have anycast gateways, VMs on those VNIs which are routing to other networks can use the same gateway

information while behind different leaf pairs. When those VMs route, their local leaf switches will always be

doing the routing. This replaces VRRP and enables VMs to migrate from one leaf pair to another without the

need to change the network configuration. It also eliminates hairpinning and improves link utilization since

routing is performed much closer to the source.

This topology also uses a traditional centralized gateway for routing to external networks, such as the

Internet. VNI 1616 does not have anycast gateways configured, and VMs on this VNI use the physical

gateway/firewall switch as their default gateway. When VMs on VNI 1616 send packets to another VNI or

Internet destination, their packets are tunneled to the third leaf pair where their VXLAN information is stripped

off, and the original frame is exposed. The destination MAC address matches the gateway/firewall and is

forwarded according to its routing table.

With the addition of static routes, VMs with anycast gateways also use the indirect gateway to communicate

with external networks or VMs on VNI 1616. In this example, default routes are installed on all leaf switches

pointing to the indirect gateway. This way, a VM on VNI 1614, for instance, can get the benefit of anycast

gateways, while also being able to access resources made available via the indirect gateway. Static routes

are also used at the indirect gateway to route traffic from external networks or VNI 1616 back to VNIs 1614

and 1615.

Note: VNIs can any number be in the range 1-16777215.