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[OpenStack Infra <1608400@xxxxxxxxxxxxxxxxxx>]

Reviewed:  https://review.openstack.org/550676
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=fbe308bdc12191c187343b5ef103dea9af738380
Submitter: Zuul
Branch:    master

commit fbe308bdc12191c187343b5ef103dea9af738380
Author: Swaminathan Vasudevan <SVasudevan@xxxxxxxx>
Date:   Wed Mar 7 19:03:42 2018 -0800

    DVR: Fix allowed_address_pair IP, ARP table update by neutron agent
    
    Allowed_address_pair IP when associated with a network port will
    inherit the services MAC.
    Right now the ARP entry is updated with the last MAC that it is
    associated with. But when allowed_address_pair IPs are used in
    the context of VRRP the MAC keeps switching between the MASTER
    and SLAVE. VRRP instance sends out GARP, but the ARP entry in the
    router namespace is not getting updated based on the GARP.
    
    This might cause the VRRP IP and the service using the IP to fail.
    
    Since we having been adding the ARP entry with NUD state as
    PERMANENT, the ARP entries are set for ever and does not adopt the
    GARP sent out by the VRRP instance.
    
    This will cause instances associated with DVR routers to have a
    service interruption.
    
    So the proposed patch will add the ARP entry for the Allowed address
    pair with NUD for 'REACHABLE'.
    This allows the Allowed_address_pair IP MAC to be updated on the
    fly.
    
    Change-Id: I43c3471f5d259e8c2ee1685398a06a4680c0bfcd
    Closes-Bug: #1608400


** Changed in: neutron
       Status: In Progress => Fix Released

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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:
  Fix Released

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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