DELL SONIC · EVPN TYPE-5

Dell SONiC: a border leaf with type-5 routes

L2 is also the border leaf. In Vrf-T1 it reaches an outside network, stood in for by Loopback 100 (10.100.100.0/24). A host route says where one host is, but the outside is a whole prefix, which needs a type-5 route. The VRF’s BGP instance already redistributes connected routes and advertises them, so give it the network to announce.

Dell SONiC track · Dell Enterprise SONiC-style · 4 objectives

Open in simulator More Dell SONiC labs

Objectives

The simulator ticks each one as soon as the network meets it.

On L2, create Loopback 100 in Vrf-T1 with 10.100.100.1/24.
show bgp l2vpn evpn route type prefix on L1: 10.100.100.0/24 is there as a type-5 route from 10.10.10.2.
L1 has the route in its VRF: show ip route vrf Vrf-T1.
Ping 10.100.100.1 from PC1.

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Before you start

advertise ipv4 unicast turns the VRF’s BGP routes into type-5 routes, with the VRF’s route-target and L3 VNI. On a real border leaf, the prefixes come from a routing protocol with the outside router, such as eBGP in the VRF.

Concept

BGP EVPN: a control plane for VXLAN

BGP EVPN replaces flood-and-learn with BGP routes in the L2VPN EVPN address family. Each VTEP advertises an inclusive-multicast route (type 3) per VNI, so the others know to replicate to it, and a MAC route (type 2) per local host, so remote MACs are known before any traffic flows. A spine is usually the iBGP route reflector.

Concept

A leaf-spine fabric on Dell switches

Every leaf connects to every spine, and no leaf connects to another leaf, so any two leaves are two hops apart over several equal paths. eBGP routes between loopbacks form the underlay, usually with one ASN per leaf pair. EVPN then runs on the same BGP sessions: VTEPs announce their VNIs and hosts, and tunnels form from those routes. SONiC can peer without link addresses: ipv6 enable and neighbor interface are enough.