yahoo-eng-team team mailing list archive

[Hemanth Nakkina <1933092@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

In one of the cloud environment, the FIP attached to the Octavia
Loadbalancer VIP is not reachable. After analysis, we found the ARP
entry for SNAT IP is missing in the qrouter namespace where Amphora VM
is running. And so the return packets are not forwarded from qrouter to
snat on active l3-agent node.

Version:
Ubuntu Ussuri packages (16.3.2 point release)
DVR+SNAT+L3HA enabled

Expectation is to have PERMANENT arp entry for snat ip on qrouter namespace on all compute nodes
192.168.33.238 dev qr-4ee692e0-7a lladdr fa:16:3e:25:6a:73 used 38/38/38 probes 0 PERMANENT

How to reproduce:

Attaching a script to simulate the problem (without octavia) with following steps
1. network/subnet/router is created, network attached to router
2. verify if qrouter on all compute nodes has arp entries related to snat ip
3. if arp entries exists, delete network/subnet/router
4. Repeat steps 1,2,3 until missing arp entry is observed.

I am able to reproduce missing arp entry sometimes in 3rd loop and
sometimes in 6th loop.

Observed arp entries for snat ip is updated at the following places [1]
[2] but get_snat_interfaces() and get_ports_by_subnet() are not updated
with snat ip in non-working cases.

[1] https://opendev.org/openstack/neutron/src/commit/dfd04115b059c2263cdd8ac44ccc2ec47614bcc3/neutron/agent/l3/dvr_local_router.py#L570
[2] https://opendev.org/openstack/neutron/src/commit/dfd04115b059c2263cdd8ac44ccc2ec47614bcc3/neutron/agent/l3/dvr_local_router.py#L317

** Affects: neutron
     Importance: Undecided
         Status: New

-- 
You received this bug notification because you are a member of Yahoo!
Engineering Team, which is subscribed to neutron.
https://bugs.launchpad.net/bugs/1933092

Title:
  snat arp entry missing in qrouter namespace

Status in neutron:
  New

Bug description:
  In one of the cloud environment, the FIP attached to the Octavia
  Loadbalancer VIP is not reachable. After analysis, we found the ARP
  entry for SNAT IP is missing in the qrouter namespace where Amphora VM
  is running. And so the return packets are not forwarded from qrouter
  to snat on active l3-agent node.

  Version:
  Ubuntu Ussuri packages (16.3.2 point release)
  DVR+SNAT+L3HA enabled

  Expectation is to have PERMANENT arp entry for snat ip on qrouter namespace on all compute nodes
  192.168.33.238 dev qr-4ee692e0-7a lladdr fa:16:3e:25:6a:73 used 38/38/38 probes 0 PERMANENT

  How to reproduce:

  Attaching a script to simulate the problem (without octavia) with following steps
  1. network/subnet/router is created, network attached to router
  2. verify if qrouter on all compute nodes has arp entries related to snat ip
  3. if arp entries exists, delete network/subnet/router
  4. Repeat steps 1,2,3 until missing arp entry is observed.

  I am able to reproduce missing arp entry sometimes in 3rd loop and
  sometimes in 6th loop.

  Observed arp entries for snat ip is updated at the following places
  [1] [2] but get_snat_interfaces() and get_ports_by_subnet() are not
  updated with snat ip in non-working cases.

  [1] https://opendev.org/openstack/neutron/src/commit/dfd04115b059c2263cdd8ac44ccc2ec47614bcc3/neutron/agent/l3/dvr_local_router.py#L570
  [2] https://opendev.org/openstack/neutron/src/commit/dfd04115b059c2263cdd8ac44ccc2ec47614bcc3/neutron/agent/l3/dvr_local_router.py#L317

To manage notifications about this bug go to:
https://bugs.launchpad.net/neutron/+bug/1933092/+subscriptions