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Asymmetric routing with SR Linux in EVPN VXLAN fabrics

This post dives deeper into the asymmetric routing model on SR Linux. The topology in use is a 3-stage Clos fabric with BGP EVPN and VXLAN, with server s1 single-homed to leaf1, s2 dual-homed to leaf2 and leaf3 and s3 single-homed to leaf4. Hosts s1 and s2 are in the same subnet, 172.16.10.0/24 while s3 is in a different subnet, 172.16.20.0/24. Thus, this post demonstrates Layer 2 extension over a routed fabric as well as how Layer 3 services are deployed over the same fabric, with an asymmetric routing model.

The physical topology is shown below:

srlinux-asymm-1

Multi-vendor EVPN VXLAN setup with Containerlab

In this post, we deploy a multivendor EVPN L2 overlay fabric, with BGP in the underlay as well. The entire fabric deployment is automated with Ansible, and Containerlab is used to define and deploy the actual topology.

Introduction and topology

This post continues to build and showcase the power of containerlab. In this post, we will create a multivendor EVPN topology for L2 overlays. The vendors included are Arista (vEOS), Juniper (vQFX), Cumulus (Cumulus VX) and Cisco (N9Kv). Every piece of software used here is free (some might be behind a login, so you'll have to register to get access to image downloads).

The topology is as follows:

topology1

Juniper vQFX and Containerlab

In this post, we look at how Containerlab can be used to quickly spin up vQFX topologies for network validation and testing. We'll walk through the entire process - how to build docker images from vQFX images, what happens behind the scenes when bringing these containers up and how to build/verify your topology.

What is Containerlab?

Containerlab is an open source, network validation/testing platform that allows you to easily spin up network labs and manage end to end lab life cycle. It supports several network operating systems, across many vendors. As of this writing, it supports Nokia SR Linux, Juniper cRPD, Cumulus VX, Arista cEOS. Outside of these natively containerized operating systems, it also supports VM based devcies like Junipers vQFX and vMX, Nexus 9000v, IOS XRv, Arista vEOS and so on.

More information can be found on their homepage - https://containerlab.srlinux.dev/