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RE: applying backup command to serial interfaces posted 11/10/2006
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	It depends if LMI is end-to-end.  If LMI is end-to-end then if
one side goes down or there is a failure somewhere in the cloud the
other end's circuit status will reflect this.  

	Whenever you configure the backup interface command you need to
ask yourself what will cause the line protocol of the interface to go
down.  For Frame Relay the line protocol of the main interface is based
on receiving LMI keepalive from the Frame Relay cloud.  For Frame Relay
subinterfaces it is based on the circuit status.  If all the circuits on
the subinterface are in Inactive or Deleted status then the line
protocol will go down.

	For PPPoFR you need to put the command on the Serial interface
not the virtual-template.  The reason why is that the virtual-template's
line protocol is always down, as the virtual-access is the logical
instance that is used from the template.  However you can't access the
virtual-access interface directly to configure it so you can't put the
backup interface command on it.


HTH,

Brian McGahan, CCIE #8593 (R&S/SP)
bmcgahan@xxxxxxxxxxxxxxxxxxxxxx 

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> -----Original Message-----
> From: nobody@xxxxxxxxxxxxxx [mailto:nobody@xxxxxxxxxxxxxx] On Behalf
Of
> Frank
> Sent: Friday, November 10, 2006 8:50 AM
> To: Michael Zuo; ccie >> Cisco certification
> Subject: Re: applying backup command to serial interfaces
> 
> Michael Zuo schrieb:
> 
> Actually you have to put keepalives to the PVC to track the circuit
for
> the backup
> command. If one side shuts down, the other side will not recognize it.
> You could use a tunnel over the cirtuit also to track the availability
> and put the
> backup command on the tunnel.
> 
> Frank
> > Just curious: when using the "backup" command on a frame relay
> > interface, should it always be applied to a subinterface to able to
> > track the VC status, even when the IP is configured on the main
> > interface or a virtual-template interface (PPPoFR)?
> >
> >
> >
> >
> >
> > Basically, I'd like to find out when backup command is supposed to
go
> > the main interface and when a subinterface...
> >
> >
> >
> >
> >
> > Thanks in Advance...
> >
> >
_______________________________________________________________________
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
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>
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