[Rdo-list] Problem with floating IP

Miguel Angel Ajo Pelayo mangelajo at redhat.com
Fri Apr 17 08:42:11 UTC 2015

To troubleshoot this I’d recommend you 

1) doing a tcpdump in the controller node, on the external interface attached to br-ex,
and find what’s going on, 

tcpdump -e -n -v -v -v -i ethX

note: as per your schema you may use an “external flat network”
(no segmentation) from your network/controller node, so the packets going out from the router
should not be tagged in your tcpdump.

If you set the external network as vlan tagged, you may have to change it into flat. (such operation
may require removing the floating ips from instances, removing legs from router (External, and internal),
and then removing the router, then the external network/subnet).

In a separate terminal, it may help to ..
2) look for the router netns:

# ip netns

note : this is the “virtual router”, it lives in a network namespace which is another isolated
instance of the linux networking stack., you will find the interfaces and IPs attached with
the following command:

# ip netns exec qrouter-8f2f7e69-02c3-4b75-9b25-e23b64757935 ip a

(here look for the external leg of the router, it will have the external router IP and the floating ip attached)
it should look like qg-xxxxxxxx-xx

# ip netns exec qrouter-8f2f7e69-02c3-4b75-9b25-e23b64757935 tcpdump -e -n -v -v -v -i qg-xxxxxxx-xx

Please tell us how is it going .

> On 17/4/2015, at 9:48, pauline phaure <phaurep at gmail.com> wrote:
> Hello everyone,
> I have some troubles making the floating IP work. When I associate a floating IP to my instance, the instance can reach the neutron-router and ping but cannot ping the external gateway. any ideas where to look?
> <image.png>
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Miguel Angel Ajo

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