Re: ICMPv6 too big Packet will makes the network unreachable

On Wed, Oct 14, 2015 at 5:18 PM, Sheng Yong [off-list ref] wrote:

Hi, Rongqing,

Cced Martin KaFai Lau [off-list ref]

It seems you trigger the problem that I met before, here is the link of disucssion:
http://www.spinics.net/lists/netdev/msg314717.html

You can try these patches to check if they resolve your problem:
7035870d1219 | 2015-05-03 | ipv6: Check RTF_LOCAL on rt->rt6i_flags instead of rt->dst.flags
653437d02f1f | 2015-04-28 | ipv6: Stop /128 route from disappearing after pmtu update

thanks,
Sheng

On 10/13/2015 3:09 PM, Li RongQing wrote:

quoted

1. Machine with 2001:1b70:82a8:18:650:65:0:2 address, and receive wrong
icmp packets
    root@du1:~# ifconfig
    eth10.650 Link encap:Ethernet  HWaddr 74:c9:9a:a7:e5:88
              inet6 addr: fe80::76c9:9aff:fea7:e588/64 Scope:Link
              inet6 addr: 2001:1b70:82a8:18:650:65:0:2/80 Scope:Global
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              RX packets:1 errors:0 dropped:0 overruns:0 frame:0
              TX packets:9 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:0
              RX bytes:104 (104.0 B)  TX bytes:934 (934.0 B)

2. ICMPv6 packet is as below.

   ###[ Ethernet ]###
     dst       = 74:C9:9A:A7:E5:88
     src       = ae:4f:44:f2:10:cc
     type      = 0x86dd
   ###[ IPv6 ]###
        version   = 6
        tc        = 0
        fl        = 0
        plen      = None
        nh        = ICMPv6
        hlim      = 64
        src       = 2001:1b70:82a8:18:650:65:0:4
        dst       = 2001:1b70:82a8:18:650:65:0:2

   ###[ ICMPv6 Packet Too Big ]###
           type      = Packet too big
           code      = 0
           cksum     = None
           mtu       = 1280

   ###[ IPv6 ]###
              version   = 6
              tc        = 0
              fl        = 0
              plen      = None
              nh        = ICMPv6
              hlim      = 255
              src       = 2001:1b70:82a8:18:650:65:0:2
              dst       = 2001:1b70:82a8:18:650:65:0:2
   ###[ ICMPv6 Neighbor Discovery - Neighbor Advertisement ]###
                 type      = Neighbor Advertisement
                 code      = 0
                 cksum     = None
                 R         = 1
                 S         = 0
                 O         = 1
                 res       = 0x0
                 tgt       = 2001:1b70:82a8:18:650:65:0:2

   ##### Test #####

3. Send ICMPv6  with Scapy to trigger fault.

   conf.iface='eth1'
   eth = Ether(src='ae:4f:44:f2:10:cc', dst='74:C9:9A:A7:E5:88')
   base = IPv6(src='2001:1b70:82a8:18:650:65:0:4',
dst='2001:1b70:82a8:18:650:65:0:2')
   ptb = ICMPv6PacketTooBig(type=2)
   packet = eth/base/ptb
   ptb_payload_na_base = IPv6(src='2001:1b70:82a8:18:650:65:0:2',
dst='2001:1b70:82a8:18:650:65:0:2')
   ptb_payload_na = ICMPv6ND_NA(type=136, tgt='2001:1b70:82a8:18:650:65:0:2')
   ptb_payload = ptb_payload_na_base/ptb_payload_na
   packet = packet/ptb_payload
   sendp(packet, iface="eth1.650", count=1)

4.  route information  will enter the faulty state after Wait 600 seconds,

   root@du1:~# ip route get 2001:1b70:82a8:18:650:65:0:2
   local 2001:1b70:82a8:18:650:65:0:2 dev lo  proto none  src
2001:1b70:82a8:18:650:65:0:2  metric 0  expires 7sec mtu 1280

   root@du1:~# ip route get 2001:1b70:82a8:18:650:65:0:2
   local 2001:1b70:82a8:18:650:65:0:2 dev lo  proto none  src
2001:1b70:82a8:18:650:65:0:2  metric 0  expires 3sec mtu 1280

   root@du1:~# ip route get 2001:1b70:82a8:18:650:65:0:2
   2001:1b70:82a8:18:650:65:0:2 dev eth10.650  src
2001:1b70:82a8:18:650:65:0:2  metric 0
       cache
   root@du1:~#
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