From: James (james@towardex.com)
Date: Wed Sep 08 2004 - 04:23:22 GMT-3
In Lab 6 on practice labs , under ISDN, we see the following:
"Make sure that yourrouting proto is passed accross the isdn link only when
the connectivity is established"
In order to accomplish the above, we simply make sure 'dialer-list 1 proto
clns permit', and ensure that "clns_is" is not included -- thereby making
ISIS establish adjacency only when ISDN circuit is already up and running.
So far so good. (well also ensuring dialer map clns yadda yadda..)
"The ISDN link should only pass a routing protocol if R5-fa0/0 is down."
Now.. it says ISDN should pass routing protocol when fa0/0 on R5 is down.
That is good and all when FA0/0 sudden goes down while ISDN is already dialed
and running. But what happens when ISDN is NOT dialed and turned off (due to
idle traffic)?? The previous requirement says that isdn must only establish
ISIS protocol when the circuit is already dialed and running.
So the thought process here in my head is to use 'backup interface' on fa0/0
or another mechanism that will trigger ISDN to dial itself during fa0/0 outage.
This will ensure ISIS will establish adjacency then, after fa0/0 outage,
since backup interface brought up the ISDN circuit physically.
But the solution in the book made no configuration changes for this
requirement.
Well, not making any config changes for this requirement works well when the
isdn is already dialed and up and running, but guarantees nothing when proctor
reboots your routers and isdn is shut down at boot time :(
Any ideas, clues?
Thanks,
-J
-- James Jun TowardEX Technologies, Inc. Technical Lead Network Design, Consulting, IT Outsourcing james@towardex.com Boston-based Colocation & Bandwidth Services cell: 1(978)-394-2867 web: http://www.towardex.com , noc: www.twdx.net
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