Damien
46c68b42bd
Make hosts/campus-host{1,2}_interfaces the source of truth for the
campus host IP and default route, and have clab simply invoke 'ifup
eth1' at container start to apply it. Previously the bound interfaces
file was unused and the real config lived in the YAML exec block,
which was misleading.
BusyBox ifup in the network-multitool image needs 'address' plus
'netmask' rather than a CIDR, so split the address accordingly. Also
add 'post-up ip route replace default via <fabric-gw>' so the fabric
default overrides the management DHCP default even when one is already
installed.
Host Interface Configuration Files
This directory contains network interface configuration files for Alpine Linux hosts in the ContainerLab topology.
Files
DC hosts
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)
Campus hosts
Campus hosts are single-attached to a Campus access switch (enterprise user endpoint
pattern — no LACP bond, no VLAN trunking on the host side). Each host sits in a single
access VLAN that maps to VRF gold.
campus-host1_interfaces- Configuration for campus-host1 (VLAN 60 VRF gold 10.60.60.101/24, GW 10.60.60.1)campus-host2_interfaces- Configuration for campus-host2 (VLAN 70 VRF gold 10.60.70.102/24, GW 10.60.70.1)
Usage
Each file is mounted to /etc/network/interfaces in its respective host container via ContainerLab's binds feature:
host1:
kind: linux
image: alpine:latest
binds:
- hosts/host1_interfaces:/etc/network/interfaces
Format
Files use Debian/Alpine ifupdown format.
DC hosts (dual-homed via LACP to access switches)
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
Campus hosts (single-attached, no bonding, no VLAN tagging)
auto lo
iface lo inet loopback
auto eth1
iface eth1 inet static
address <ip-address>/<mask>
gateway <gateway>
Key Concepts
DC: LACP Bonding
- DC hosts use mode 4 (802.3ad LACP) bonding
- Dual-homed to MLAG leaf pairs — typical for DC servers that need NIC-level redundancy
- Requires matching LACP configuration on switches
Campus: Single-attached user endpoints
- Campus hosts use a single
eth1interface connected to an access port - Redundancy is handled at the access-switch layer (the access switch is itself dual-homed via LACP to the leaf MLAG pair), not at the host
- This matches the realistic enterprise pattern for PCs, phones, printers, etc.
VLAN Tagging
- DC hosts: VLAN tagging happens in the host via
bond0.<vlan_id>sub-interfaces (e.g., bond0.40, bond0.34, bond0.78); switch ports are trunks - Campus hosts: no tagging on the host; the access switch places untagged frames
into
switchport access vlan <id>
IP Addressing
- Static IP configuration on the host interface (sub-interface for DC,
eth1for Campus) - Subnet assignment based on VLAN ID pattern (e.g., VLAN 40 = 10.40.40.0/24)
Modification
To change host configuration:
- Edit the appropriate
host*_interfacesfile - Commit changes to git
- 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
- Main README - Project overview and quick start
- TROUBLESHOOTING.md - Troubleshooting guide
- END_TO_END_TESTING.md - Testing procedures