Subject: Re: [PATCH V2 0/1] neighbour: Support broadcast ARP in neighbor PROPE state

From: YOSHIFUJI Hideaki/吉藤英明<[email-masked]>
Date: Thu, 12 Mar 2015 18:28:30 +0900

Hi,

Ulf samuelsson wrote:
> That also means that you increase the number of broadcasts in incomplete state.
> Is that really desirable?

In NUD_INCOMPLETE state, neighbour subsystem *skips* sending unicast probes
and send multicast probes mcast_solicit times. If you do not increase
the number of mcast_solicit, the number of multicast probes in
NUD_INCOMPLETE will not increased.

--yoshfuji

>
> Best Regards
> Ulf Samuelsson
> [email-masked]
> +46  (722) 427 437
>
>
>> 12 mar 2015 kl. 09:42 skrev YOSHIFUJI Hideaki <[email-masked]>:
>>
>> Hello.
>>
>> yzhu1 wrote:
>>> The state machine is in the attachment.
>>>
>>> Best Regards!
>>> Zhu Yanjun
>>>> On 03/12/2015 02:58 PM, Zhu Yanjun wrote:
>>>> V2:
>>>>    set ARP_PROBE_BCAST default N.
>>>>
>>>> V1:
>>>>    Have a problem with an HP router at a certain location, which
>>>>    is configured to only answer to broadcast ARP requests.
>>>>    That cannot be changed.
>>>>
>>>>    The first ARP request the kernel sends out, is a broadcast request,
>>>>    which is fine, but after the reply, the kernel sends unicast requests,
>>>>    which will not get any replies.
>>>>
>>>>    The ARP entry will after some time enter STALE state,
>>>>    and if nothing is done it will time out, and be removed.
>>>>    This process takes to long, and I have been told that it is
>>>>    difficult to makes changes that will eventually remove it.
>>>>
>>>>    Have tried to change the state from STALE to INCOMPLETE, which failed,
>>>>    and then tried to change the state to PROBE which also failed.
>>>>
>>>>    The stack is only sending out unicasts, and never broadcast.
>>>>    Is there any way to get the stack to send out a broadcast ARP
>>>>    without having to wait for the entry to be removed?
>>
>> Neighbour subsystem will send multicast probes after unicast
>> probes in NUD_PROBE state if mcast_solicit is more than
>> ucast_solicit.  Try setting net.ipv4.neigh.*.ucast_solicit to
>> the value less than net.ipv4.neigh.*.mcast_solicit, please?
>> e.g.
>>
>> net.ipv4.neigh.eth0.mcast_solicit = 3
>> net.ipv4.neigh.eth0.ucast_solicit = 1
>>
>> --yoshfuji
>>
>>
>>>>
>>>>    I think the recommended behaviour in IPv6 is to send out 3 unicasts
>>>>    and if all fails, to send out broadcasts.
>>>>
>>>> Zhu Yanjun (1):
>>>>    neighbour: Support broadcast ARP in neighbor PROPE state
>>>>
>>>>   include/net/neighbour.h        |  7 ++++++
>>>>   include/uapi/linux/neighbour.h |  6 +++++
>>>>   include/uapi/linux/sysctl.h    |  3 +++
>>>>   kernel/sysctl_binary.c         |  3 +++
>>>>   net/core/neighbour.c           | 44 +++++++++++++++++++++++++++++---
>>>>   net/ipv4/Kconfig               | 57 ++++++++++++++++++++++++++++++++++++++++++
>>>>   net/ipv4/arp.c                 |  7 ++++--
>>>>   7 files changed, 121 insertions(+), 6 deletions(-)
>>
>> --
>> Hideaki Yoshifuji <[email-masked]>
>> Technical Division, MIRACLE LINUX CORPORATION
>> --
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-- 
吉藤英明 <[email-masked]>
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