From: christopher snow (cbsnow31@yahoo.com)
Date: Sun Feb 22 2004 - 07:25:24 GMT-3
Think about the default behavior of the router when
you redistribute from one protocol into another. For
instance, if one tells the router to redistribute rip
into ospf the router will do two steps. First, it
will take all the rip routes in the routing table
(unless filtering). Second, it will take all of the
interfaces that rip is running on by default. What
happens later, and is somewhat of a trap, is that one
may be told to redistribute a loopback address into
OSPF later in the scenrio. When one does a
redistribute connected under OSPF with a route-map
that references the loopback, the default behavior
(second step above) has now been manually overridden.
By manually specifing the loopback address alone, one
has now inadvertantly removed the interfaces/subnets
that were once being used by default (second step
above). You must now manually add those
subnets/interfaces to the connected route-map. Lab it
up and check it out :)
HTH,
Chris Snow
--- alsontra@hotmail.com wrote:
> Are you saying that ospf removed a connected
> interface from its LSA database
> when you used the redistribute connected command on
> another interface?
>
> Alsontra
>
>
> I noticed this behavior a few days ago, after the
> fact. This time I
> caught it red handed. What a nightmare in the lab
> this could be.
> Here's what I was doing, the local isis interface
> didn't get
> redistributed, which is normal.
> I use tags, so I included the local interface (s0.24
> 136.10.24.0/29)
> with the proper tag for isis into ospf, fixing what
> isis should have
> done. (step 1)
> Immediately my rip (s1 136.10.12.0/24) connected
> route which was
> perfectly stable dropped out of ospf. (step 2)
> I did nothing to effect the redistribution between
> rip and ospf! It has
> to be some logic being turned off by a specific
> redistribute connected
> cmd being present in the ospf config.
> To fix it, I added another statement to my route-map
> using the right tag
> for rip, and the route came back. (step 3)
> Remote router watching ospf routes
> Step 1) -
> RT: add 136.10.24.0/29 via 136.10.56.5, ospf metric
> [110/1065]
> Step 2)
> RT: del 136.10.12.0/24 via 136.10.56.5, ospf metric
> [110/1065]
> RT: delete subnet route to 136.10.12.0/24
> Step 3)
> RT: add 136.10.12.0/24 via 136.10.56.5, ospf metric
> [110/1065]
>
------------------------------------------------------------------------
> ----
> Step 1)
> redistribute connected metric 1000 metric-type 1
> subnets route-map
> connectedisis
> route-map connectedisis permit 10
> match interface Serial0.24
> set tag 444
> Step 3)
> route-map connectedisis permit 15
> match interface Serial1
> set tag 111
>
------------------------------------------------------------------------
> ----
> Is this normal? Maybe a bug in my ios? I hadn't
> noticed it before, but
> I notice a lot more now than I used to.
>
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