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Host bond interfaces down - eth slaves not brought up #9

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opened 2025-11-28 14:10:08 +00:00 by Damien · 0 comments
Damien commented 2025-11-28 14:10:08 +00:00
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Problem

Host bond interfaces show state LOWERLAYERDOWN - ping between hosts fails even though EVPN/VXLAN is working correctly.

Root Cause

In the ContainerLab topology, hosts create bonded interfaces but never bring up the slave interfaces (eth1/eth2) before adding them to the bond. The bond cannot come up if its slaves are down.

Fix Applied ✅

Added ip link set ethX up commands BEFORE adding interfaces to the bond in all host exec sections.

Previous sequence (broken):

- ip link add bond0 type bond mode balance-rr
- ip link set eth1 master bond0  # eth1 is still DOWN
- ip link set eth2 master bond0  # eth2 is still DOWN
- ip link set bond0 up  # bond0 can't come up because slaves are down

New sequence (fixed):

- ip link add bond0 type bond mode balance-rr
- ip link set eth1 up  # Bring eth1 up first
- ip link set eth2 up  # Bring eth2 up first
- ip link set eth1 master bond0
- ip link set eth2 master bond0
- ip link set bond0 up

Fixed Hosts

  • host1 (VLAN 40 on VTEP1) ✅
  • host2 (VLAN 34 on VTEP2) ✅
  • host3 (VLAN 40 on VTEP3) ✅
  • host4 (VLAN 78 on VTEP4) ✅

File updated: evpn-lab.clab.yml

After redeployment, ping between hosts should work over the EVPN/VXLAN fabric.

## Problem Host bond interfaces show `state LOWERLAYERDOWN` - ping between hosts fails even though EVPN/VXLAN is working correctly. ## Root Cause In the ContainerLab topology, hosts create bonded interfaces but never bring up the slave interfaces (eth1/eth2) before adding them to the bond. The bond cannot come up if its slaves are down. ## Fix Applied ✅ Added `ip link set ethX up` commands BEFORE adding interfaces to the bond in all host exec sections. **Previous sequence (broken):** ```yaml - ip link add bond0 type bond mode balance-rr - ip link set eth1 master bond0 # eth1 is still DOWN - ip link set eth2 master bond0 # eth2 is still DOWN - ip link set bond0 up # bond0 can't come up because slaves are down ``` **New sequence (fixed):** ```yaml - ip link add bond0 type bond mode balance-rr - ip link set eth1 up # Bring eth1 up first - ip link set eth2 up # Bring eth2 up first - ip link set eth1 master bond0 - ip link set eth2 master bond0 - ip link set bond0 up ``` ## Fixed Hosts - host1 (VLAN 40 on VTEP1) ✅ - host2 (VLAN 34 on VTEP2) ✅ - host3 (VLAN 40 on VTEP3) ✅ - host4 (VLAN 78 on VTEP4) ✅ File updated: `evpn-lab.clab.yml` After redeployment, ping between hosts should work over the EVPN/VXLAN fabric.
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Reference: Damien/arista-evpn-vxlan-clab#9
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