From c0f680a0b65bfef2298034096490d7381b33509b Mon Sep 17 00:00:00 2001
From: Damien Arnodo <damien@noreply.localhost>
Date: Sat, 29 Nov 2025 17:25:47 +0000
Subject: [PATCH] Add README for hosts directory explaining interface
 configuration files

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 hosts/README.md | 75 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 hosts/README.md

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+# Host Interface Configuration Files
+
+This directory contains network interface configuration files for Alpine Linux hosts in the ContainerLab topology.
+
+## Files
+
+- `host1_interfaces` - Configuration for host1 (VLAN 40, IP 10.40.40.101)
+- `host2_interfaces` - Configuration for host2 (VLAN 34, IP 10.34.34.102)
+- `host3_interfaces` - Configuration for host3 (VLAN 40, IP 10.40.40.103)
+- `host4_interfaces` - Configuration for host4 (VLAN 78, IP 10.78.78.104)
+
+## Usage
+
+Each file is mounted to `/etc/network/interfaces` in its respective host container via ContainerLab's `binds` feature:
+
+```yaml
+host1:
+    kind: linux
+    image: alpine:latest
+    binds:
+        - hosts/host1_interfaces:/etc/network/interfaces
+```
+
+## Format
+
+Files use Debian/Alpine ifupdown format with bonding and VLAN extensions:
+
+```
+auto lo
+iface lo inet loopback
+
+auto bond0
+iface bond0 inet manual
+    bond-mode 4                  # LACP (802.3ad)
+    bond-miimon 100
+    bond-lacp-rate 1
+    bond-slaves eth1 eth2
+
+auto bond0.<vlan>
+iface bond0.<vlan> inet static
+    address <ip-address>
+    netmask 255.255.255.0
+    vlan-raw-device bond0
+```
+
+## Key Concepts
+
+### LACP Bonding
+- All hosts use **mode 4** (802.3ad LACP) bonding
+- Dual-homed to MLAG leaf pairs for redundancy
+- Requires matching LACP configuration on switches
+
+### VLAN Tagging
+- Hosts handle VLAN tagging via sub-interfaces
+- Format: `bond0.<vlan_id>` (e.g., bond0.40, bond0.34, bond0.78)
+- Switch ports are configured as trunks allowing specific VLANs
+
+### IP Addressing
+- Static IP configuration on VLAN sub-interfaces
+- Subnet assignment based on VLAN ID pattern (e.g., VLAN 40 = 10.40.40.0/24)
+
+## Modification
+
+To change host configuration:
+
+1. Edit the appropriate `host*_interfaces` file
+2. Commit changes to git
+3. Redeploy the lab: `sudo containerlab deploy -t evpn-lab.clab.yml --reconfigure`
+
+No need to manually configure hosts after deployment - these files ensure clean, repeatable deployments.
+
+## See Also
+
+- [HOST_INTERFACE_CONFIGURATION.md](../docs/HOST_INTERFACE_CONFIGURATION.md) - Detailed documentation
+- [DEPLOYMENT_GUIDE.md](../DEPLOYMENT_GUIDE.md) - Lab deployment instructions