From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steffen Klassert Subject: Re: Question: should local address be expired when updating PMTU? Date: Tue, 3 Feb 2015 10:28:46 +0100 Message-ID: <20150203092845.GT13046@secunet.com> References: <54CF3348.40207@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: , , , To: shengyong Return-path: Received: from a.mx.secunet.com ([195.81.216.161]:40769 "EHLO a.mx.secunet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751202AbbBCJ2z (ORCPT ); Tue, 3 Feb 2015 04:28:55 -0500 Content-Disposition: inline In-Reply-To: <54CF3348.40207@huawei.com> Sender: netdev-owner@vger.kernel.org List-ID: 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?