From: yzhu1 <Yanjun.Zhu@windriver•com>
To: "Ulf Samuelsson" <ulf.samuelsson@ericsson•com>,
"YOSHIFUJI Hideaki/吉藤英明" <hideaki.yoshifuji@miraclelinux•com>,
brian.haley@hp•com, davem@davemloft•net,
alexandre.dietsch@windriver•com, clinton.slabbert@windriver•com,
kuznet@ms2•inr.ac.ru, jmorris@namei•org, kaber@trash•net,
netdev@vger•kernel.org
Cc: "YOSHIFUJI Hideaki (USAGI Project)" <yoshfuji@linux-ipv6•org>
Subject: Re: [PATCH V2 0/1] neighbour: Support broadcast ARP in neighbor PROPE state
Date: Thu, 19 Mar 2015 10:14:27 +0800 [thread overview]
Message-ID: <550A3103.6000503@windriver.com> (raw)
In-Reply-To: <55096C44.2020604@ericsson.com>
On 03/18/2015 08:15 PM, Ulf Samuelsson wrote:
> On 03/18/2015 11:34 AM, YOSHIFUJI Hideaki/吉藤英明 wrote:
>> Hi,
>>
>> Ulf Samuelsson wrote:
>>>
>>> On 03/12/2015 09:42 AM, YOSHIFUJI Hideaki wrote:
>>>> 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 dont see how, and I would like to focus on code discussion.
>>>
>>> Below is simplified pseudo code of the timer handler
>>> after you have reached REACHABLE the first time.
>>>
>>> "mcast_solicit" is not used at all.
>>>
>>> It is only used when in INCOMPLETE state as far as I can tell.
>>
>> OK, I found I made this change in 2003:
>>
>> From d12fd76789e80ae337408834f45dae7cba23fc55 Mon Sep 17 00:00:00 2001
>> From: Hideaki Yoshifuji <yoshfuji@linux-ipv6•org>
>> Date: Sun, 6 Jul 2003 23:32:45 +1000
>> Subject: [PATCH] [NET] Send only unicast NSs in PROBE state.
>>
>> ---
>> net/core/neighbour.c | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/net/core/neighbour.c b/net/core/neighbour.c
>> index c640ad5..001fdb4 100644
>> --- a/net/core/neighbour.c
>> +++ b/net/core/neighbour.c
>> @@ -608,7 +608,9 @@ next_elt:
>> static __inline__ int neigh_max_probes(struct neighbour *n)
>> {
>> struct neigh_parms *p = n->parms;
>> - return p->ucast_probes + p->app_probes + p->mcast_probes;
>> + return (n->nud_state & NUD_PROBE ?
>> + p->ucast_probes :
>> + p->ucast_probes + p->app_probes + p->mcast_probes);
>> }
>>
>>
>> As I recall, I was hesitating adding new sysctl knob, but now I am
>> okay to have knob to enable mcast probes in PROBE state as well.
>> (By default, it should NOT send multicast probe (expecially for IPv6)
>> in PROBE state.)
>>
>> How about these?
>> - introduce probe_mcast_probes knob, default to 0.
>> - Change neigh_max_probes() to reflect that.
>>
>> Then, arp_colisit() and ndict_solicit() should send multicast probes
>> in PROBE state as well, if probe_mcast_probes is set to positive
>> value.
>>
>> Will this work for you?
>>
>> Regards,
>
> "probe_mcast_probes" as a name sucks...
>
> It is also confusing since it is doing something very similar to
> ucast_solicit, app_solicit and mcast_solicit.
>
> As I see it, it should be named "<XXX>_solicit" to show
> how it is related to the rest of the sysctl entries.
>
> If XXX is "bcast", as in my suggestion, is less important.
>
> "mcast_probe_solicit" would work for me, but prefer "bcast_solicit".
>
> What exactly is wrong with that name?
> =================
>
> Your suggestion was my initial suggestion for solution, and after
> consideration
> by Wind River reviewers it was rejected, since it affected IPv6.
> Did not check in what way.
>
> The WR proposed solution, which is the one that was sent to the list,
> was to keep neigh_max_probes as is, but add check for "bcast_solicit"
> inside
> the timer handler, which they think makes sure that it affects IPv4
> processing only.
>
> The solution should allow broadcast ARP requests in IPv4 after unicast
> ARP
> requests without making IPv6 incompatible with RFCs.
>
> Yanjun may be able to comment further.
Yes. I prefer to this solution since this only affects IPv4.
Best Regards!
Zhu Yanjun
>
> Best Regards,
> Ulf Samuelsson
>
>
>>
>> --yoshfuji
>>
>>>
>>>
>>> Best Regards,
>>> Ulf Samuelsson
>>>
>>>
>>>
>>>>
>>>>>>
>>>>>> 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(-)
>>>>>>
>>>>>
>>>>
>>>
>>
>
>
>
>
next prev parent reply other threads:[~2015-03-19 2:14 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-12 6:58 [PATCH V2 0/1] neighbour: Support broadcast ARP in neighbor PROPE state Zhu Yanjun
2015-03-12 6:58 ` [PATCH V2 1/1] " Zhu Yanjun
2015-03-12 10:05 ` YOSHIFUJI Hideaki/吉藤英明
2015-03-12 7:10 ` [PATCH V2 0/1] " yzhu1
2015-03-12 8:42 ` YOSHIFUJI Hideaki
2015-03-12 8:59 ` Ulf samuelsson
2015-03-12 9:28 ` YOSHIFUJI Hideaki/吉藤英明
2015-03-12 9:45 ` Ulf samuelsson
2015-03-12 10:16 ` YOSHIFUJI Hideaki
2015-03-18 8:51 ` Ulf Samuelsson
2015-03-18 10:34 ` YOSHIFUJI Hideaki/吉藤英明
2015-03-18 12:15 ` Ulf Samuelsson
2015-03-18 13:22 ` YOSHIFUJI Hideaki/吉藤英明
2015-03-18 15:12 ` Ulf Samuelsson
2015-03-19 2:42 ` yzhu1
2015-03-19 2:14 ` yzhu1 [this message]
2015-03-19 2:24 ` yzhu1
2015-03-12 19:22 ` David Miller
2015-03-16 12:39 ` Ulf Samuelsson
2015-03-19 5:52 ` yzhu1
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