AT&T blocking individual IP addresses

Scott Howard scott at doc.net.au
Wed Dec 9 09:22:50 CST 2009


As of about an hour ago AT&T appear to have started blocking access to a few
of our IP addresses. This is being done at a /32 level, and the IP addresses
above and below are still allowed through.

Has anyone seen them do this before, or know who I need to contact to get it
fixed?  AT&T won't talk to me as I'm not a customer...

Traceroute to the blocked IPs from AT&T all end at :
  5 cr2.phlpa.ip.att.net (12.122.3.226) [MPLS: Labels 20559/17406 Exp 0] 116
msec 20 msec 20 msec
  6 cr2.cl2oh.ip.att.net (12.122.2.209) [MPLS: Labels 20527/17406 Exp 0] 24
msec 20 msec 20 msec
  7 cr1.cl2oh.ip.att.net (12.122.2.125) [MPLS: Labels 0/17406 Exp 0] 24 msec
20 msec 20 msec
  8 cr82.dtrmi.ip.att.net (12.123.139.154) [MPLS: Label 16623 Exp 0] 24 msec
20 msec 20 msec
  9 gar4.dtrmi.ip.att.net (12.122.102.89) 20 msec 20 msec 20 msec
 10 12.87.238.238 [AS 7018] 24 msec 20 msec 24 msec
 11 12.87.238.237 [AS 7018] !A  *  *

Traceroute to the neighboring IP addresses don't go anywhere near the above
path, so it's apparently a blackhole of sorts.

  Scott.



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