North American Network Operators Group

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RE: Routing through non-addressable space???

  • From: Simon Higgs
  • Date: Sat Jan 26 04:07:27 2002

At 09:35 PM 1/25/02 -0600, you wrote:

Mmmmmm... this trace is from an @Work/Excite circuit that is about to go dark. The "cable modem" is (as far as I can tell) the Cisco 2600 at the customer site. Either that or @Work's customer gateway address.

Cable modems actually "have" two IP's: one rfc1918 that they use for
provisioning purposes and in the actual IP of the cable modem device,
one real IP that they pass on to the end-user's device.  Many of the
newer cable modems are now showing the private IP in traces where
previously they'd pass and not respond to ICMP.  As for why, who knows?
My best guess is to ease tracking down offending IP's vs. users.

Michael Graham

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Turpin, Mark
Sent: Friday, January 25, 2002 8:43 PM
To: 'Simon Higgs'; '[email protected]'
Subject: RE: Routing through non-addressable space???

Routing through a cable interface that has a 10.x address as its primary
address would be my first guess, esp. due to the 24.x address.

int cable3/0
ip address 10.x.x.x. x.x.x.x.x
ip address public.for.cpe.equip mask.mask.mask.mask secondary


Mark Turpin
Charter NOC
[email protected]

-----Original Message-----
From: Simon Higgs [mailto:[email protected]]
Sent: Friday, January 25, 2002 8:47 PM
To: [email protected]
Subject: Routing through non-addressable space???

Can someone explain this trace to me. How on earth did the
get inserted into the last hop?

#    IP address       Host name                                Round

4 64 ms
5 71 ms
6     Unavailable                         79 ms
7          94 ms
8                     No response
9          110 ms
10                  112 ms
11        120 ms
12    Unavailable                         134 ms
13   Unavailable                         141 ms
Best Regards,