Wrong Gateway IP Specified for External Neutron Network

Problem

• Floating IPs are unreachable for VMs on a particular external network or subnet.
• VMs with Floating IPs on this subnet are unable to reach the internet or otherwise don't possess any external connectivity.

# ping 8.8.4.4PING 8.8.4.4 (8.8.4.4) 56(84) bytes of data.From 169.254.109.47 icmp_seq=1 Destination Host UnreachableFrom 169.254.109.47 icmp_seq=2 Destination Host Unreachable

• The gateway IP is unreachable from the corresponding 'fip-' namespace (residing on the hypervisor for DVR environments, which is default).

$ sudo ip netns exec fip-6655b95d-297f-415e-b4b2-8d2eff2c4d36 ip rule0: from all lookup local32766: from all lookup main32767: from all lookup default2852023599: from all iif fpr-6490dd2d-0 lookup 285202359$ sudo ip netns exec fip-6655b95d-297f-415e-b4b2-8d2eff2c4d36 ip route show table 2852023599default via 146.xx.xxx.xxx dev fg-20345b50-bf$ sudo ip netns exec fip-6655b95d-297f-415e-b4b2-8d2eff2c4d36 ping -c4 146.xx.xxx.xxxPING 146.xx.xxx.xxx (146.xx.xxx.xxx) 56(84) bytes of data.From 146.xx.xxx.xxx icmp_seq=1 Destination Host UnreachableFrom 146.xx.xxx.xxx icmp_seq=2 Destination Host UnreachableFrom 146.xx.xxx.xxx icmp_seq=3 Destination Host UnreachableFrom 146.xx.xxx.xxx icmp_seq=4 Destination Host Unreachable

Environment

• Platform9 Managed OpenStack - All Versions
• Neutron

Cause

The wrong gateway IP is specified for the Neutron subnet which is associated with the affected VM(s) or networking is misconfigured such that the gateway IP isn't reachable.

Resolution

Clarity UI

1. Login to Clarity UI.
2. Navigate to > Networks.
3. Click on the name of the network.
4. Navigate to > Subnets.
5. Choose the subnet that needs to be modified.
6. Click on "Edit Subnet"
7. Edit the "Gateway IP" field.
8. Click "Update Subnet".

Screen_Shot_2021-04-09_at_9_47_18_AM.png

OpenStack CLI

1. List the networks.

$ openstack network list

2. Show the subnet based on the list of subnet UUIDs returned.

$ openstack subnet show [UUID]

3. Edit the subnet's gateway IP.

$ openstack subnet set --gateway [IP] [UUID]

Additional Information

OVH – vRack – Gateway IPs