Re: schein.debian.org

On 2011-06-01T18:07:26-0300, Henrique de Moraes Holschuh <[email protected]> wrote:
> On Wed, 01 Jun 2011, Gerald Turner wrote:
> > Henrique de Moraes Holschuh <[email protected]> writes:
> >  $ tracepath6 schein.debian.org
> >   1?: [LOCALHOST]                        0.031ms pmtu 1480
> >   1:  shub-niggurath.unzane.com                             0.162ms
> >   1:  shub-niggurath.unzane.com                             0.360ms
> >   2:  gturner-1.tunnel.tserv14.sea1.ipv6.he.net             6.576ms
> >   3:  gige-g2-6.core1.sea1.he.net                           5.654ms
> >   4:  10gigabitethernet9-1.core1.sjc2.he.net               26.522ms
> >   5:  10gigabitethernet3-2.core1.pao1.he.net               34.657ms
> >   6:  he.pao1.isc.org                                      29.855ms
> >   7:  int-0-0-0.r1.sjc3.isc.org                            31.418ms asymm 5
> >   8:  schein.debian.org                                    27.519ms reached
> >       Resume: pmtu 1480 hops 8 back 59
> 
> 8 hops to get to shein, and *59* hops to get back?!
> 
> That path is hopelessly broken.  In fact, this is so weird I'd guess
> something is screwing up the TTL fields in the way.

That's usual. Most of the "back" numbers reported by tracepath and
tracepath6 are in the vicinity of 59, yet this causes no breakage
elsewhere. I even have a "back 59" to shub-niggurath.unzane.com from
another he.net IPv6 tunnel:

% tracepath6 shub-niggurath.unzane.com
 1?: [LOCALHOST]                        0.091ms pmtu 1480
 1:  kenyon.tunnel.tserv3.fmt2.ipv6.he.net                31.427ms
 1:  kenyon.tunnel.tserv3.fmt2.ipv6.he.net                31.832ms
 2:  gige-g5-19.core1.fmt2.he.net                         26.653ms
 3:  10gigabitethernet1-1.core1.sjc2.he.net               23.876ms
 4:  10gigabitethernet4-3.core1.sea1.he.net               49.969ms
 5:  2001:470:0:9b::2                                     46.620ms
 6:  shub-niggurath.unzane.com                            50.540ms reached
     Resume: pmtu 1480 hops 6 back 59

Another example on native IPv6 (I receive mail on IPv6 just fine from
liszt.debian.org):

% tracepath6 liszt.debian.org
 1?: [LOCALHOST]                        0.022ms pmtu 1500
 1:  2600:3c01:ffff:0:ca4c:75ff:fef5:d63f                  0.541ms
 1:  2600:3c01:ffff:0:ca4c:75ff:fef5:d63f                  0.481ms
 2:  10gigabitethernet2-3.core1.fmt1.he.net                6.630ms
 3:  10gigabitethernet1-2.core1.sjc2.he.net                0.947ms
 4:  10gigabitethernet3-3.core1.den1.he.net               28.013ms
 5:  10gigabitethernet1-1.core1.chi1.he.net               61.588ms
 6:  10gigabitethernet7-2.core1.nyc4.he.net               71.757ms
 7:  10gigabitethernet3-3.core1.lon1.he.net              136.335ms
 8:  10gigabitethernet1-1.core1.ams1.he.net              144.150ms
 9:  ge-0-0-0.peer1.ams.man-da.net                       145.886ms asymm 10
10:  ge-0-1-4-400.core1.fra1.ix.f.man-da.net             149.567ms asymm 11
11:  ge-2-0-4-400.core1.rz.hda.da.man-da.net             150.975ms asymm 13
12:  te-2-3-0-403.core1.sm.tu.da.man-da.net              150.295ms
13:  ge-0-2-400.cust1.sm.tu.da.man-da.net                151.566ms asymm 12
14:  fw01-man-da.ayous.org                               150.839ms asymm 13
15:  liszt.debian.org                                    152.388ms reached
     Resume: pmtu 1500 hops 15 back 51

-- 
Kenyon Ralph

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