Datacenter Fabric: Arista EVPN-MLAG & Nokia SR Linux EVPN-ESI

This project implements a high-fidelity Datacenter Fabric simulation using Containerlab. It demonstrates a hybrid Spine-Leaf architecture integrating Arista EOS and Nokia SR Linux network operating systems, showcasing two distinct approaches to Layer 2 redundancy and multi-homing: MLAG and EVPN All-Active Multihoming (ESI).

Architecture & Design

Physical Topology (Clos Network)

The fabric follows a standard 2-tier Clos architecture:

• Spine Layer: 2x Arista cEOS (DCS-7050CX3-32S) acting as the IP fabric backbone.
• Leaf Layer: 4x VTEPs split into two distinct redundancy domains:
  • Pod A (Leaf1/Leaf2): Arista cEOS (DCS-7050SX3-48YC8) configured in an MLAG pair.
  • Pod B (Leaf3/Leaf4): Nokia SR Linux (IXR-D2L) configured for EVPN ESI Multihoming.
• Compute: 4x Linux Hosts (dual-homed) simulating bare-metal servers via LACP bonds.

Multi-Homing Implementations

A key objective of this lab is to contrast legacy MC-LAG implementations with modern EVPN standards.

1. Arista MLAG (Host1 & Host3)

Hosts connected to leaf1 and leaf2 utilize Arista MLAG (Multi-Chassis Link Aggregation).

• Control Plane: The switches synchronize LACP state and MAC tables via a dedicated Peer-Link (Port-Channel 551) and an out-of-band Keepalive.
• Data Plane: To the downstream host, the two switches appear as a single LACP system (same System ID). Traffic is load-balanced across both links.
• Forwarding: Traffic received on the peer-link is subject to MLAG forwarding rules to prevent loops.

2. Nokia EVPN All-Active ESI (Host2 & Host4)

Hosts connected to leaf3 and leaf4 utilize EVPN All-Active Multihoming (RFC 7432).

• Control Plane: There is no proprietary peer-link or state synchronization protocol between the leafs. Instead, both leafs are configured with the same Ethernet Segment Identifier (ESI) (e.g., 01:11:11:11:11:11:11:00:00:01) on their access interfaces.
• BGP EVPN: Both leafs advertise Type-4 (Ethernet Segment) and Type-1 (Auto-Discovery) routes. Remote VTEPs (Spines/other Leafs) learn that the segment is reachable via both VTEPs (Aliasing), enabling ECMP toward the segment.
• LACP: Both leafs are manually configured with the same LACP System ID and Priority to satisfy the host's bonding requirements, but operate independently.

Network Overlays

• Underlay: eBGP (IP Fabric).
• Overlay: iBGP EVPN-VXLAN.
• Encapsulation: VXLAN (VNI 10xxx mapped to VLANs).

Lab Lifecycle Management

Prerequisites

• Linux Environment with KVM support.
• Containerlab (latest stable).
• Docker runtime.
• Required Container Images:
  • arista/ceos:4.31.4M (or compatible)
  • ghcr.io/nokia/srlinux:25.10
  • git.as73.inetsix.net/docker/multitool:latest

Deployment Workflow

1. Instantiate the Fabric:

   sudo containerlab deploy --topo clab-atd-datacenter.clab.yml

2. Hot Reconfiguration (Apply changes without destroy):

   sudo containerlab deploy --topo clab-atd-datacenter.clab.yml --reconfigure

3. Teardown:

   sudo containerlab destroy --topo clab-atd-datacenter.clab.yml --cleanup

Authentication

Arista devices

• Username: admin (password: none)
• Username: arista (password: arista)

Nokia devices

• Username: admin (password: NokiaSrl1!)

Host devices

• Username: root (password: password123)

Management IPs

Arista EOS containers

Hostname	Management Interface	IP Address
Spine1	Management0	192.168.72.11/24
Spine2	Management0	192.168.72.12/24
Leaf1	Management0	192.168.72.13/24
Leaf2	Management0	192.168.72.14/24
Leaf3	Management0	192.168.72.15/24
Leaf4	Management0	192.168.72.16/24

Linux containers

Hostname	Managemnt Interface	IP Address
Host1	Eth0	192.168.72.17/24
Host2	Eth0	192.168.72.18/24
Host3	Eth0	192.168.72.19/24
Host4	Eth0	192.168.72.20/24