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Re: Using backup interface to backup multipoint serial interface posted 11/09/2003
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Alec,

You have to consider the F.R. switch on this scenario. The backup 
interface will come up only if the physical link between R1 and
the frame-relay switch goes physically down. One way to simulate
this is to access the frame-relay switch (if you can) and shutdown
the interface to which R1 connects (shut/no shut on R1's serial 
will not work). Obviously doing so will also kill your PVC to R3.

In other words, the backup interface will only come up if R1 looses
connectivity to the FR switch, and since in your case R1 uses a 
multipoint subinterface, if this link goes down, so will your PVC
to R3...

HTH,

Enrico




"Pun, Alec CL" wrote:
> 
> I just read a sample configuration to use backup interface to backup
> multipoint serial interface.
> R1 serial interface is a multipoint interface having DLCI to R2 & R3.  My
> question is if I use backup interface bri0 on the serial interface of R1
> only, in case R2 is down, R1 may not kick up the ISDN connection 'coz the
> PVC to R3 is still UP and that makes the serial interface remains UP too.
> Please correct if I made any wrong assumtions.
> 
> thanks
> alec
> 
> R1 ----- ISDN ----- R2
>  |                         |
>  |---------FR -----------|
>  |
>  |
> R3
> 
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