Connectivity issues and packet inspection

[Steve Bertrand]

Hi everyone,

I'm having an issue internally here that I can't quite wrap my head 
around. I'll use noc.sixxs.net as my example case.

One of my core routers installs the route after being received via BGP, 
and can reach it:

Sending 5, 100-byte ICMP Echos to 2001:838:1:1:210:DCFF:FE20:7C7C, 
timeout is 2 seconds:
!!!!!

A box, connected via a switch to one of the router ports can ping the 
router, but not sixxs. (The same happens for ipv6.google.com). It 
appears the packets are not making the return trip.

However, the same box that can not ping sixxs/google, can ping 
freebsd.org, so I know that I haven't broken everything.

I have noticed some serious oddities within my router, and a few of the 
BGP peerings the last few days, so I'm sure it may have something to do 
with that, but I can't pinpoint it.

Could a few kind souls have a look as to what kind of path they see to 
2607:f118::/32, especially those who can not ping 2607:f118::b6?

Also, something else I don't quite grasp. I believe it has something to 
do with source addr selection, but I'm just off to further delve into 
this now.

This is a ping from a box to another box ::5 -> ::b6, both within the 
same prefix /64 (however there is one switch hop to make). The 
link-local addr is the router on the same prefix. I don't understand why 
there is an ICMP redirect involved in this situation (ie, why is the 
router involved at all). Can someone advise what I am missing?

19:56:27.669731 IP6 fe80::20b:46ff:fe3e:f341 > 2607:f118::5: ICMP6, 
redirect, 2607:f118::b6 to 2607:f118::b6, length 160

19:56:27.706583 IP6 fe80::20b:46ff:fe3e:f341 > 2607:f118::5: ICMP6, 
redirect, 2607:f118::b6 to 2607:f118::b6, length 160

19:56:27.713575 IP6 fe80::20b:46ff:fe3e:f341 > 2607:f118::5: ICMP6, 
redirect, 2607:f118::b6 to 2607:f118::b6, length 208

19:56:27.716855 IP6 fe80::20b:46ff:fe3e:f341 > 2607:f118::5: ICMP6, 
redirect, 2607:f118::b6 to 2607:f118::b6, length 192

19:56:27.869865 IP6 fe80::20b:46ff:fe3e:f341 > 2607:f118::5: ICMP6, 
redirect, 2607:f118::b6 to 2607:f118::b6, length 160

19:56:28.018445 IP6 fe80::20b:46ff:fe3e:f341 > 2607:f118::5: ICMP6, 
redirect, 2607:f118::b6 to 2607:f118::b6, length 120

Steve