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External network is not reachable from subnet

asked 2017-07-14 10:10:13 -0600

Sofiane68 gravatar image


I created a public net ( gateway , a private one ( and I created a router between them.

The problem is the router gateway is set to and I cannot associate floating IP to my instances.

My router has two interfaces : (down) and which is up.

When I want to assoaciate a floating IP, this is the error :

Error: External network 5635b60a-87d0-4447-a387-e75532009ae5 is not reachable from subnet 3c4b0863-afd1-4a61-ac76-4c81e881b424. Therefore, cannot associate Port 60524d40-4ce9-4400-889d-06d40baca5e1 with a Floating IP. Neutron server returns request_ids: ['req-c965fe7e-01d4-4351-80f0-b2cf57d6f7c2']


# Ansible managed

# Linux bridge agent physical interface mappings

#physical_interface_mappings = dbaas-mgmt:eth14

# Linux bridge agent VXLAN networks

enable_vxlan = True
vxlan_group =
# VXLAN local tunnel endpoint
local_ip =
l2_population = False

# Agent

# Security groups
firewall_driver = iptables
enable_security_group = True


# Ansible managed

# ML2 general
type_drivers = flat,vlan,vxlan,local
tenant_network_types = vxlan,flat
mechanism_drivers = linuxbridge
extension_drivers = port_security

# ML2 flat networks
flat_networks = flat

# ML2 VLAN networks
network_vlan_ranges =

# ML2 VXLAN networks
vxlan_group =
vni_ranges = 1:1000

# Security groups
enable_security_group = True
enable_ipset = True

Any ideas please?

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There is no route between the subnet to which the port is connected, and the network from where you obtained the floating IP. Perhaps the easiest way to check this is the network topology screen in the GUI. Otherwise, list all your networks and subnets and correlate them with the router interfaces.

Bernd Bausch gravatar imageBernd Bausch ( 2017-07-14 20:26:58 -0600 )edit

The fact that the gateway port is down is counter-intuitive but seems to be normal (i.e. that's the case in my cloud as well). I don't know if there is any method in this madness.

Bernd Bausch gravatar imageBernd Bausch ( 2017-07-14 20:28:36 -0600 )edit

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answered 2019-02-26 02:54:42 -0600

grkim gravatar image

Try this.

openstack router set router01 --external-gateway ext_subnet

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Asked: 2017-07-14 10:10:13 -0600

Seen: 2,049 times

Last updated: Feb 26 '19