Weird traceroute problem - SOLVED

[Christopher Smith]

It appears I've been bitten by a bug in the vlan code.  I noticed while  
tcpdumping that the icmp time-exceeded packets were getting back to the  
vlan parent interface, but not to the vlan interface itself.  This  
thread appears to describe the underlying problem:

http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF- 
8&threadm=3E05A429.7080506_obluda.cz%40ns.sol.net&rnum=5&prev=/ 
groups%3Fq%3Dfreebsd%2Bhardware%2Bvlan%2Bbug%26hl%3Den%26lr%3D%26ie%3DUT 
F-8%26oe%3DUTF- 
8%26selm%3D3E05A429.7080506_obluda.cz%2540ns.sol.net%26rnum%3D5


And this PR referenced in it has a patch that fixes the problem:

http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/46405


I'm guessing this will only affect some people, as the problem was  
intermittent (depending on the intervening routers).  The ones that  
were sending back the ICMP packets that were triggering the bug were  
"Cisco Catalyst 6500s running native IOS" (the networking people here  
tell me).  Presumably these routers change the priority of some ICMP  
packets ?

In any event, can someone please merge the patch in the PR referenced  
above into the main source tree, because the problem it triggers is  
rather mystifying :).

-- 
+- Christopher Smith, Systems Administrator  
------------------------------+
|  Server & Security Group, Information Technology Services              
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|  The University of Queensland, Brisbane, Australia, 4072               
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+- Ph +61 7 3365 4046 | email csmith at its.uq.edu.au | Fax +61 7 3365  
4065 -+