Re: 127.x.x.x

RFC says NO

but just called to mind old days with SetOS 6500
From the MSFC, telnet to 127.0.0.X, in which X is the slot, service module .
:)

Thanks
Shahid Ansari
Kuwait

On Wed, Apr 21, 2010 at 6:59 AM, Joe Astorino <jastorino_at_ipexpert.com>wrote:

> William,
>
> I seem to recall something in the 127/8 space being used internally for NTP
> as well...I would have to look up the exact address
>
>
> Sent from my Verizon Wireless BlackBerry
>
> Regards,
>
> Joe Astorino - CCIE #24347
> Sr. Technical Instructor - IPexpert
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> -----Original Message-----
> From: William McCall <william.mccall_at_gmail.com>
> Date: Tue, 20 Apr 2010 22:53:16
> To: ccie.unnumbered<ccie.unnumbered_at_gmail.com>
> Cc: ccielab<ccielab_at_groupstudy.com>
> Subject: Re: 127.x.x.x
>
> No.
>
> For at least 2 reasons:
>
> 1) RFC 1700 [1] and RFC 3330 [2] both specify that the 127.0.0.0/8
> should never appear on any network anywhere. Cisco complies with this
> directive [3] in 12.4T (and, I'm willing to bet, most any other
> version of IOS but the old timers can tell me about how 11.0 allowed
> this)
>
> 2) These loopback addresses are used internally for, primarily,
> service modules and linecards (anyone, is there any other place this
> is used?) and would most likely break stuff. For example, attaching to
> a line card on the 12K GSR (IOS, not sure about XR) results in a funky
> telnet connection to an address like 127.0.0.17.
>
> For the scenario you proposed on your Linux box before, you can create
> a sub interface on the loopback interface. Example:
>
> ifconfig lo:0 192.168.12.1 netmask 255.255.255.0
>
> And now you have a new network for handling your terminal server.
>
> HTH
>
> --
> William McCall, CCIE #25044
>
> [1] http://www.faqs.org/rfcs/rfc1700.html
> [2] http://www.faqs.org/rfcs/rfc3330.html
> [3]
> http://www.cisco.com/en/US/customer/docs/ios/ipaddr/configuration/guide/iad_config_ipadd_ps6441_TSD_Products_Configuration_Guide_Chapter.html
>
>
> On Tue, Apr 20, 2010 at 10:27 PM, ccie.unnumbered
> <ccie.unnumbered_at_gmail.com> wrote:
> > Is there a way that 127.x.x.x can be assigned to any interface on a Cisco
> > router/switch?
> >
> > Thanks,
> > Jack
> >
> >
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Received on Wed Apr 21 2010 - 10:18:28 ART