From: Tim Fletcher (tim@fletchmail.net)
Date: Thu Dec 19 2002 - 13:52:12 GMT-3
One correction below.
>Date: Thu, 19 Dec 2002 11:33:35 -0500
>To: "Sara Li" <saralilin@hotmail.com>, Sam.MicroGate@usa.telekom.de,
>ccielab@groupstudy.com
>From: Tim Fletcher <tim@fletchmail.net>
>Subject: Dial - Was: Mastering the core was not enough......
>
>At 12:02 PM 12/19/2002 +0000, Sara Li wrote:
>>could you share with your experience on ISDN? like which method to use,
>>dialer-watch/Demand-circuit?
>
>The method you use depends on the lab requirements. Most labs will give
>you some kind of clue what to use, you just have to know the differences
>to be able to choose one that meets the requirements. I will try to
>highlight some of the differences between some of the different technologies.
>
>Backup Interface
>
>Shuts down the backup interface until the primary interface goes down.
>It's the equivalent of doing a shut on the backup interface when the
>primary interface comes up, and a no shut when the primary interface goes down.
>- The backup interface does not have to be a dial interface.
>- Dial connections will still use interesting traffic to bring them up and
>idle out.
>- The primary physical interface must go down, before the backup can come
>up, so some frame scenarios will not work.
>- Interesting traffic cannot bring the link up when the primary is up.
>
>Dialer Watch
>
>Forces a dial connection when all of the routes in dialer watch-list
>disappear from the routing table.
>- Only works with dial interfaces.
>- You can have multiple entries in a dialer watch-list.
>- Doesn't care about interesting traffic, stays up until the primary
>routes are restored (although interesting traffic may be used to bring up
>additional links).
Interesting traffic is not used to bring up additional links, load is.
>- Checks to see if the primary routes are restored every idle-timeout
>intervals.
>- Because it nails the link up, idle-timeout on the other end will cause
>the link to bounce every idle-timeout interval.
>- Interesting traffic can still bring the link up
>
>Demand Circuit
>
>Only prevents hellos from keeping the link up.
>- Any topology change will bring the link up.
>- Only works with OSPF
>
>Snapshot routing
>
>Works with DV protocols.
>- Brings the link up at preset intervals to exchange routes.
>- Topology changes do not get propagated until the interval expires.
.
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