From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brian Haley Subject: Re: How to make stack send broadcast ARP request when entry is STALE? Date: Mon, 10 Nov 2014 17:52:08 -0500 Message-ID: <54614198.7010306@hp.com> References: <545C96D6.5020204@hp.com> <3A67CF46-0BC1-4BAA-818A-0B656C6B46B6@emagii.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Cc: Netdev To: Ulf samuelsson Return-path: Received: from g2t1383g.austin.hp.com ([15.217.136.92]:23556 "EHLO g2t1383g.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751152AbaKJWwL (ORCPT ); Mon, 10 Nov 2014 17:52:11 -0500 Received: from g6t1526.atlanta.hp.com (g6t1526.atlanta.hp.com [15.193.200.69]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by g2t1383g.austin.hp.com (Postfix) with ESMTPS id 15CE42E37 for ; Mon, 10 Nov 2014 22:52:11 +0000 (UTC) In-Reply-To: <3A67CF46-0BC1-4BAA-818A-0B656C6B46B6@emagii.com> Sender: netdev-owner@vger.kernel.org List-ID: On 11/07/2014 05:11 AM, Ulf samuelsson wrote: > The HP router is configured by a customer, and they intentionally limit replies > to broadcast, and that is how they want it. So this is the crux of the problem - the customer has configured the router so that it doesn't play well with most modern network stacks that try and use unicast so they don't send unnecessary broadcast packets. I don't know why I thought this was something wrong with the router software. Did you try this? $ sudo sysctl net.ipv4.neigh.eth0.ucast_solicit=0 It works for me. And they really should re-think their decision on that configuration setting. -Brian > In the previous version of the build system, the Interpeak stack was used > and this would in PROBE state send unicast ARP request, and if that failed > send broadcast ARP. > > The native linux stack, when in PROBE state sends only unicast until it decides > that it should enter FAILED state. > > The 'mcast_probes' variable seems to be totally ignored, except the first time, > so I do not see why it is there. > > Best Regards > Ulf Samuelsson > ulf@emagii.com > +46 (722) 427 437 > > >> 7 nov 2014 kl. 10:54 skrev Brian Haley : >> >>> On 11/05/2014 07:48 AM, Ulf samuelsson wrote: >>> 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. >> >> Sorry to hear about the problem, but my only suggestions would be to try the latest firmware and/or put a call in to support. I don't happen work in the division that makes routers... >> >>> 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. >> >> You might be able to hack this by inserting an ebtables rule - check the dnat target section of the man page - don't know the exact syntax but it would probably end in '-j dnat --to-destination ff:ff:ff:ff:ff:ff' >> >> -Brian >> -- >> To unsubscribe from this list: send the line "unsubscribe netdev" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >