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From: Marek Lindner <lindner_marek@yahoo.de>
To: "Vasiliy Kulikov" <segooon@gmail.com>,
	"Linus Lüssing" <linus.luessing@web.de>
Cc: "Greg Kroah-Hartman" <gregkh@suse.de>,
	Andrew Lunn <andrew@lunn.ch>,
	Sven Eckelmann <sven.eckelmann@gmx.de>,
	Simon Wunderlich <siwu@hrz.tu-chemnitz.de>,
	devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org
Subject: Re: batman-adv: design suggestions
Date: Sat, 14 Aug 2010 16:59:13 +0200	[thread overview]
Message-ID: <201008141659.14868.lindner_marek@yahoo.de> (raw)
In-Reply-To: <20100813181833.GA5632@albatros>

On Friday 13 August 2010 20:18:33 Vasiliy Kulikov wrote:
> d) Why do you send icmp TTL exceeded for the icmp itself? E.g. in case
> of loop or/and small default TTL you'll probably get a storm of icmps.
> Exactly in this case IP silently drops TTL exceeded icmps ;)

These layer2 icmp packets are not ordinary icmp packets. We needed to provide 
a mechanism to make the network topology visible to debug tools like ping or 
traceroute which normally "see" no more than one hop as they operate on 
layer3. Hence, batman-adv does not send an icmp packet for each payload TTL 
exceeded but for traceroute only. I recommend reviewing the traceroute code to 
understand how this is supposed to work:
http://www.open-mesh.org/browser/trunk/batctl/traceroute.c

I'd be interested to learn about a problematic scenario in which this 
mechanism breaks.

Regards,
Marek

  parent reply	other threads:[~2010-08-14 14:59 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-08-09 20:34 batman-adv: design suggestions Vasiliy Kulikov
2010-08-09 20:53 ` Sven Eckelmann
2010-08-12 12:48   ` Vasiliy Kulikov
2010-08-14 14:50     ` Marek Lindner
2010-08-14 16:19       ` Vasiliy Kulikov
2010-08-14 17:10         ` Marek Lindner
2010-08-13 18:18 ` Vasiliy Kulikov
2010-08-13 23:25   ` Sven Eckelmann
2010-08-14 14:59   ` Marek Lindner [this message]
2010-08-14 16:13     ` Vasiliy Kulikov

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