"Bullock, Jason (1125)" wrote:
>
> Hey Listers.
>
> I was thinking about this cool thing one of the cisco TAC engineers did when
> helping me troubleshoot a tricky network problem a few months ago. They
> looped up my serial interface on a 2600 to verify the WIC card was working
> properly, and that the attached CSU was not faulty. They configured the WIC
> interface to show up and up , even though there T1 was down.
> The problem is , I can not remember the command sets that were run to make
> this work. ! Anyone know this one? ugh.
>
S/he probably had you do:
interace s0
loopback
which commands the serial NIC to assert the signal lead to the DCE called
loopback. If the DCE (CSU/DSU or whatever) is optioned to obey this, then
it will perform a local loopback. So whatever the router sends is reflected
back to it on the receive side.
Note this is totally different from the default HDLC keepalive message
that is exchanged between the two routers.
Marty Adkins Email: [EMAIL PROTECTED]
Mentor Technologies Phone: 240-568-6526
133 National Business Pkwy WWW: http://www.mentortech.com
Annapolis Junction, MD 20701 Cisco CCIE #1289
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