From: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
To: Timo Ter?s <timo.teras@iki.fi>
Cc: Patrick McHardy <kaber@trash.net>,
davem@davemloft.net, netdev@vger.kernel.org
Subject: Re: [PATCH RESEND] ip_gre: sendto/recvfrom NBMA address
Date: Wed, 24 Oct 2007 00:20:36 +0400 [thread overview]
Message-ID: <20071023202036.GA12066@ms2.inr.ac.ru> (raw)
In-Reply-To: <471E19E5.5040509@iki.fi>
Hello!
Me wrote:
> Ack. This is good idea.
>
> Frankly, I was sure ip_gre worked in this way all these years.
> I do not remember any reasons why it was crippled.
>
> The only dubious case is when next hop is set using routing tables.
> But code in ipgre_tunnel_xmit() is ready to accept this situation,
> it checks for zero destination address and fixes it when it is able to.
Nevertheless, it does not work.
The reason is that NOARP arp entries on device with initialized
hard_header are initialized not to all zeros, but to dev->dev_addr.
So that, netxthop from routing tables is ignored and all gre packets
are lost in loopback. Not good.
The problem can be ignored. I am even not sure that someone uses
this feature. Actually, it was not recommended in documentation.
Alternatively, arp.c can be changed to generate 0 addresses instead
of dev->dev_addr. Normally it is equally good, but I am not sure
about possible side effects.
Another thoughts?
Alexey
next prev parent reply other threads:[~2007-10-23 20:20 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-23 14:31 [PATCH RESEND] ip_gre: sendto/recvfrom NBMA address Timo Teräs
2007-10-23 14:33 ` Patrick McHardy
2007-10-23 15:08 ` Timo Teräs
2007-10-23 15:57 ` Timo Teräs
2007-10-23 16:10 ` Patrick McHardy
2007-10-23 19:03 ` Alexey Kuznetsov
2007-10-24 3:32 ` David Miller
2007-10-23 20:20 ` Alexey Kuznetsov [this message]
2007-10-24 5:54 ` Timo Teräs
2007-10-24 10:08 ` Alexey Kuznetsov
2007-12-18 13:59 ` [RFC][PATCH][IPV4] ip_gre: use skb->{mac,network}_header consistently Timo Teräs
2007-12-19 18:10 ` [PATCH][IPV4] ip_gre: set mac_header correctly in receive path Timo Teräs
2007-12-20 8:11 ` David Miller
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