[ovs-dev] [PATCH] Handle gratuitous ARP requests and replies in tnl_arp_snoop()

Manohar Krishnappa Chidambaraswamy manohar.krishnappa.chidambaraswamy at ericsson.com
Wed Apr 11 07:52:39 UTC 2018

Thanx Ben.


On 11/04/18, 4:57 AM, "Ben Pfaff" <blp at ovn.org> wrote:

    On Thu, Apr 05, 2018 at 12:20:27PM +0000, Manohar Krishnappa Chidambaraswamy wrote:
    > Problem:
    > ========
    > In user-space tunneling implementation, tnl_arp_snoop() snoops only ARP
    > *reply* packets to resolve tunnel nexthop IP addresses to MAC addresses.
    > Normally the ARP requests are periodically sent by the local host IP stack,
    > so that the ARP cache in OVS is refreshed and entries do not time out.
    > However, if the remote tunnel nexthop is a VRRP IP, and the gateway
    > periodically sends gratuitous ARP *requests* to announce itself,
    > tnl_arp_snoop() treats them as INVALID. Consequently, the ARP cache in OVS
    > expires after 10 minutes, which results in dropping of the next packet(s)
    > until a new ARP request is responded to.
    > Fix:
    > ====
    > Enhance the tunnel neighbor resolution logic in OVS to not only snoop on
    > ARP replies but also on gratuitous ARP requests.
    > Signed-off-by: Jan Scheurich <jan.scheurich at ericsson.com>
    > From: Manohar K C <manohar.krishnappa.chidambaraswamy at ericsson.com>
    > CC: Jan Scheurich <jan.scheurich at ericsson.com>
    Thanks, applied to master.

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