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From: Steffen Klassert <steffen.klassert@secunet•com>
To: shengyong <shengyong1@huawei•com>
Cc: <davem@davemloft•net>, <netdev@vger•kernel.org>,
	<yangyingling@huawei•com>, <hannes@redhat•com>
Subject: Re: Question: should local address be expired when updating PMTU?
Date: Tue, 3 Feb 2015 10:28:46 +0100	[thread overview]
Message-ID: <20150203092845.GT13046@secunet.com> (raw)
In-Reply-To: <54CF3348.40207@huawei.com>

On Mon, Feb 02, 2015 at 04:20:24PM +0800, shengyong wrote:
> Hi, David Miller
> Since commit 81aded246 (ipv6: Handle PMTU in ICMP error handlers), the entries
> in neigh table may get expired. But in the situation:
> 
>           Host only
>     PC <------------> Virtual Machine
> 
> a packet is sent from PC to VM, and the packet looks like:
> -----------------------------------
> | IPv6 (src=PC-addr, dst=VM-addr) |
> |---------------------------------|
> |     ICMPv6 (Packet Too Big)     |
> |---------------------------------|
> | IPv6 (src=VM-addr, dst=VM-addr) |
> |---------------------------------|
> | ICMPv6 (Neighbor Advertisement) |
> -----------------------------------
> 
> Then the local addr on VM will be updated with an expire value. After the
> lifetime of the local addr is expired, the VM is unreachable from PC.
> 
> 	# ip -6 route list table local
> 	local fe80::1 dev lo  metric 0 *expire 596*

We first need to find out why you receive this Packet Too Big message,
can you capture this packet somehow? Then we have to see why this loopback
route gets a pmtu update from that packet. Is the destination address
of the Packet Too Big message really fe80::1?

  parent reply	other threads:[~2015-02-03  9:28 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-02  8:20 Question: should local address be expired when updating PMTU? shengyong
2015-02-02 21:31 ` David Miller
2015-02-03  0:52 ` Alex Gartrell
2015-02-03  1:28   ` shengyong
2015-02-03  2:10   ` Calvin Owens
2015-02-03  3:21     ` shengyong
2015-02-03  9:28 ` Steffen Klassert [this message]
2015-02-03 10:54   ` shengyong
2015-02-03 12:01     ` Steffen Klassert
2015-02-04  1:59       ` shengyong
2015-02-05  7:21         ` Steffen Klassert
2015-02-27  2:37           ` shengyong
2015-02-27 10:32             ` Steffen Klassert
2015-03-30 10:32             ` Steffen Klassert
2015-03-30 10:33               ` [PATCH RFC 1/3] ipv6: Fix after pmtu events dissapearing host routes Steffen Klassert
2015-03-30 11:15                 ` Sheng Yong
2015-03-30 18:24                 ` Martin Lau
2015-04-01  8:09                   ` Steffen Klassert
2015-03-30 10:33               ` [PATCH RFC 2/3] ipv6: Extend the route lookups to low priority metrics Steffen Klassert
2015-03-30 10:34               ` [PATCH RFC 3/3] ipv6: Don't update pmtu on uncached routes Steffen Klassert
2015-03-30 11:13               ` Question: should local address be expired when updating PMTU? Sheng Yong

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