From: John Neiberger (neiby@xxxxxxxxxx)
Date: Fri Feb 22 2002 - 19:44:17 GMT-3
I posted this on the regular list but since I haven't figured
out the solution yet I thought I'd post it here, as well. To
summarize what you're about to read, I need to figure out how
to give one Dialer interface priority over another when
accessing the same BRI. So, if Dialer0 (low priority) has
placed a call, if Dialer1 (high priority) then needs to place a
call, I want Dialer1 to preempt Dialer0 and take over the BRI.
Here's the full post:
<snip>
I was just talking to a guy I work with about this and I
thought it was an interesting scenario. It was his idea and my
first thought was that it wasn't possible, but then after a
little more pondering I decided that it might be possible.
Note: 'possible' does not mean desirable. :-) Here's the
scoop:
[A]-----------------[B]
| \
| \
| \
| \
| \
| \
| \
[C] ----------- [D]
Site A is connected to B, a disaster recovery facility, via
frame relay. A also has point-to-point connections to sites C
and D. C and D are connected via frame relay but obviously
only use the frame relay link to reach A if their own primary
link goes down.
C and D have ISDN connections configured to dial B in case both
links to A go away (Dialer Watch). Now for the twist.... What
if you wanted to configure C to dial D when the load on its
primary link reached a certain point, yet still dial B if both
point-to-point links went down?
I haven't completely figured out how to do this yet, but here's
a start. You might configure two Dialer profiles, one for each
destination. On the major interface on C you'd configure
Dialer0 as your backup interface and configure an appropriate
load. When the line utilization reaches that load, the router
would dial Site D.
Then you might configure Dialer Watch on Dialer1 and make it
dialer Site B if routes originating from Site A disappear. The
difficulty is that the Dialer interface that calls Site B would
have to have absolute priority. If the primary link goes down,
because Dialer0 is configured as a backup it might grab the BRI
first. Even if it does get there first, when Dialer Watch
kicks in, we'd have to have a way to clear the line immediately
so Dialer1 could dial out.
Is that possible? Admittedly, I'm a bit weak on DDR of this
variety, but this sounded like an interesting brain teaser.
Regards,
John
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