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[Heqing <tsinghe.7@xxxxxxxxx>]

Public bug reported:

When we set a fixed IP as allowed-address-pair IP, Neutron will notify
l3-agent to add permanent ARP entry for this IP in DVR router namespace.
But if we set the same IP to multiple ports as allowed-address-pair IP,
ARP entry with same IP but different MAC will be added multiple times.In
the end, the ARP entry will always lead us to last port that set the
fixed IP as allowed-address-pair.This makes VRRP application goes wrong.

This was noticed when deploying Octavia on Active/Standby mode.

How to reproduce:
1.Launch 2 VMs,vm-1 and vm-2, which connected to a DVR router.
2.Create an allowed-address-pair port
 Neutron port-create --name demo-port demo-net

3.Set allowed-address-pair for vm-1 and vm-2, use fixed IP of demo-port
 neutron port-update --allowed-address-pair ip_address=10.0.0.29 3c8fac1c-4b1b-4258-8b18-8d74eebb48e4
 neutron port-update --allowed-address-pair ip_address=10.0.0.29 a8b36d75-89ff-41d6-b891-fb65b7be88b4

4.Check ARP table of the DVR router.The ARP entry will always lead to 10.0.0.21(vm-1).
[root@R1Network1 ~]# ip netns exec qrouter-4832ea04-cfa1-4c43-9ca9-e916b5fd1c28 arp -n
Address                  HWtype  HWaddress           Flags Mask            Iface
10.0.0.2                 ether   fa:16:3e:78:91:99   CM                    qr-2451ce9e-fa
10.0.0.21                ether   fa:16:3e:a7:7d:7a   CM                    qr-2451ce9e-fa *
10.0.0.29                ether   fa:16:3e:a7:7d:7a   CM                    qr-2451ce9e-fa *
10.0.0.20                ether   fa:16:3e:16:da:45   CM                    qr-2451ce9e-fa *
10.0.0.3                 ether   fa:16:3e:bc:92:e9   CM                    qr-2451ce9e-fa

** Affects: neutron
     Importance: Undecided
     Assignee: Heqing (tsinghe-7)
         Status: New


** Tags: allowed-address-pair dvr

** Changed in: neutron
     Assignee: (unassigned) => Heqing (tsinghe-7)

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https://bugs.launchpad.net/bugs/1608400

Title:
  Neutron should not add ARP entry for allowed-address-pair-fixed-ip in
  DVR  router

Status in neutron:
  New

Bug description:
  When we set a fixed IP as allowed-address-pair IP, Neutron will notify
  l3-agent to add permanent ARP entry for this IP in DVR router
  namespace. But if we set the same IP to multiple ports as allowed-
  address-pair IP, ARP entry with same IP but different MAC will be
  added multiple times.In the end, the ARP entry will always lead us to
  last port that set the fixed IP as allowed-address-pair.This makes
  VRRP application goes wrong.

  This was noticed when deploying Octavia on Active/Standby mode.

  How to reproduce:
  1.Launch 2 VMs,vm-1 and vm-2, which connected to a DVR router.
  2.Create an allowed-address-pair port
   Neutron port-create --name demo-port demo-net

  3.Set allowed-address-pair for vm-1 and vm-2, use fixed IP of demo-port
   neutron port-update --allowed-address-pair ip_address=10.0.0.29 3c8fac1c-4b1b-4258-8b18-8d74eebb48e4
   neutron port-update --allowed-address-pair ip_address=10.0.0.29 a8b36d75-89ff-41d6-b891-fb65b7be88b4

  4.Check ARP table of the DVR router.The ARP entry will always lead to 10.0.0.21(vm-1).
  [root@R1Network1 ~]# ip netns exec qrouter-4832ea04-cfa1-4c43-9ca9-e916b5fd1c28 arp -n
  Address                  HWtype  HWaddress           Flags Mask            Iface
  10.0.0.2                 ether   fa:16:3e:78:91:99   CM                    qr-2451ce9e-fa
  10.0.0.21                ether   fa:16:3e:a7:7d:7a   CM                    qr-2451ce9e-fa *
  10.0.0.29                ether   fa:16:3e:a7:7d:7a   CM                    qr-2451ce9e-fa *
  10.0.0.20                ether   fa:16:3e:16:da:45   CM                    qr-2451ce9e-fa *
  10.0.0.3                 ether   fa:16:3e:bc:92:e9   CM                    qr-2451ce9e-fa

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