DELL CONTROLLER · DRIFT

Dell controller: fix a switch that drifted

The fabric was working until someone made a change directly on a switch, and PC1 has lost PC3. A controller knows what each switch should have, so it can find the difference without you reading every configuration.

Dell Controller track · Dell OS10-style + Dell SONiC-style + Cisco switch · 4 objectives

Open in simulator More Dell Controller labs

Objectives

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

Use show drift on FC1 to find the switch and the missing line.
Deploy the intent again.
No drift remains.
Ping PC3 (192.168.100.30) from PC1.

Start this lab

Before you start

Drift is any difference between intent and a switch. Here the fix is one command, because the controller still holds the truth. Without a controller, you would compare configurations by hand.

Concept

A fabric controller: intent to configuration

A controller holds what you want: spines, leaf pairs, tenants, networks. It works out each switch’s lines from that intent and the cabling. Change the intent once, and every switch follows. Because it knows what each switch should have, it can also find drift: a change made directly on a switch.

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.