neutron

[OVN] Floating IP <=> Floating IP across subnets

Bug #2038978 reported by Mohammed Naser
10
This bug affects 1 person
Affects Status Importance Assigned to Milestone
neutron
In Progress
High
Mohammed Naser

Bug Description

When using OVN, if you have a virtual router with a gateway that is in subnet A, and has a port that has a floating IP attached to it from subnet B, they seem to not be reachable.

https://mail.openvswitch.org/pipermail/ovs-dev/2021-July/385253.html

There was a fix brought into OVN with this not long ago, it introduces an option called `options:add_route` to `true`.

see: https://mail.openvswitch.org/pipermail/ovs-dev/2021-July/385255.html

I think we should do this in order to mirror the same behaviour in ML2/OVS since we install scope link routes.

Tags: ovn
Revision history for this message
Mohammed Naser (mnaser) wrote :

I've confirmed this together with dpawlik in an environment where this is broken, adding add_route has indeed fixed this issue for that nat record.

now the trick would be to add_route only if the subnet doesnt match the connected one, similar to how we can onlink routes

Revision history for this message
OpenStack Infra (hudson-openstack) wrote : Fix proposed to neutron (master)

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/897953

Changed in neutron:
status: New → In Progress
Revision history for this message
Mohammed Naser (mnaser) wrote : Re: [OVN] ARP + Floating IP issues

FYI, anyone that is running into this, the temporary workaround which restored connectivity was:

# find the NAT mapping for the FIP that is _outside_ the external gw subnet
$ ovn-nbctl find NAT external_ip=X.Y.Z.158
_uuid : 3935eb7d-dee9-4e6f-b645-f43c9fe441ff
allowed_ext_ips : []
exempted_ext_ips : []
external_ids : {"neutron:fip_external_mac"="fa:16:3e:ff:88:8a", "neutron:fip_id"="1c37787b-0b47-4802-93bc-58bccd5fb731", "neutron:fip_network_id"="7abff1a9-a103-46d0-979a-1f1e599f4f41", "neutron:fip_port_id"="d060e81c-6e7e-4d5a-b0ba-81d550193d02", "neutron:revision_number"="234", "neutron:router_name"=neutron-b97179c7-abe4-4e28-908b-952ff8abd8c4}
external_ip : "X.Y.Z.158"
external_mac : "fa:16:3e:ff:88:8a"
external_port_range : ""
gateway_port : []
logical_ip : "192.168.240.166"
logical_port : "d060e81c-6e7e-4d5a-b0ba-81d550193d02"
options : {}
type : dnat_and_snat

# enable options:add_route
$ ovn-nbctl set nat 3935eb7d-dee9-4e6f-b645-f43c9fe441ff options:add_route="true"

Upon doing this, connectivity was restored!

Mohammed Naser (mnaser)
summary: - [OVN] ARP + Floating IP issues
+ [OVN] Floating IP <=> Floating IP across subnets
Brian Haley (brian-haley)
tags: added: ovn
Changed in neutron:
importance: Undecided → High
assignee: nobody → Mohammed Naser (mnaser)
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