From: Godswill Oletu (oletu@inbox.lv)
Date: Mon Jul 10 2006 - 07:14:36 ART
It should be configured only on one end.
If you think through the technology, you will figure it out yourself:
eg in your case, when you configure backup interface on the FR interface
referencing the PPP interface, the PPP interface will go down and be in
standby mode. The only thing that will make the PPP interface to come up is
when the FR interface in down (depending on your setup, this could mean when
no DLCI is active on the FR interface, and not necessary when the interface
is down, this is why it is adviseable to use a subinterface where you can
manually assign DLCI instead of the main interface where all DLCIs get
dumped).
Now, if you configure backup interface on both ends, then both FR links must
be down before there will be any communication between both routers. This
will obviously defeat the purpose of your solution, because when Router A is
having a problem with its ISP and its ISP withdraw all the DLCIs sent to it,
the PPP interface will come up, but there will be no communication because
Router B is still going strong and as such the PPP interface on Router B is
down and in standby mode.
This is one of the few cases when over configuration KILLS and will make one
to loose points.
HTH
Godswill Oletu
CCIE #16464
----- Original Message -----
From: <bindong.shi@gmail.com>
To: <ccielab@groupstudy.com>
Sent: Monday, July 10, 2006 5:45 AM
Subject: backup interface command
> hi all:
> If R4 and R5 connected with 2 lines, FR and PPP, if we need PPP link as a
back for FR, we should configure "backup interface xx" in the FR interface,
my question is: Do we need to apply the command on 1 end only, or we need to
apply the conmmand on both end? Because I saw IEWB ver 3.0 Lab 17 Task 3.1
only configure on 1 end...
>
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