From: Scott Morris (swm@emanon.com)
Date: Mon Jul 04 2005 - 22:32:53 GMT-3
But filtering it from the routing table doesn't help you. it just makes
your routing table not care. The LSA will already be there. And that's the
trigger. You want to make the LSA not be generated.
Remember that LSAs are generated by things being placed into the OSPF
process. Things get placed into the OSPF process either through
redistribution (as Brian M. pointed out) or through the network command.
If your ISDN line is 100.100.100.0/30 as an example. You have .1 on one
side, and .2 on the other. If you can't turn off the peer neighbor route,
your routing table when the BRI line is up will contain two CONNECTED
routes:
100.100.100.0/30 and 100.100.100.x/32 where x is the other side who called
you.
The problem with LSA generation comes in how you put your network statement
in OSPF. If you have configured "network 100.100.100.0 0.0.0.3 area 12" as
an example. This is telling OSPF that any interface with an IP address in
that range is participating in OSPF and you will generate an LSA for it.
When the BRI line is up, there are TWO "interfaces" that fall in that range.
One /30 and one /32. If I generate an LSA for it, life is fine until the
line goes down. No virtual access interface, no /32 connected route. LSA
disappearing causes reason to dial under the demand-circuit rules.
Call back, and magically that /32 comes back again. So the whole process
repeats itself every 2 minutes.
So it goes back to how you specify things. Remember that in your IGP's, the
network command doesn't directly cause a route to be advertised. It causes
an interface to participate in the routing protocol, and once that occurs
the actual net and mask is brought into the RIB. So, in OSPF if you used
"network 100.100.100.y 0.0.0.0 area 12" where y is your own IP address, this
would still cause the /30 LSA to be generated. but when you had this
additional /32 CONNECTED interface appearing, OSPF would NOT be generating
an LSA for it, so you would avoid the problem.
This is also why some people claim to never have to use the peer neighbor
route commands. If their habit is to use 0.0.0.0 masks, they never create
the problem to see it occur! ;)
If you are redistributing as Brian pointed out, you may have this issue as
well, but you'll have to look at your specifics and do a little more tracing
things down!
HTH,
Scott
_____
From: Schulz, Dave [mailto:DSchulz@dpsciences.com]
Sent: Monday, July 04, 2005 8:58 PM
To: Scott Morris ; nobody@groupstudy.com; ''Aleksander Klessa' ' ;
ccielab@groupstudy.com
Subject: RE: ISDN ODC Area 0 - cant use "no peer neighobr-route"
Scott,
I would say that is I use a distribute list, and apply it through a
distribute list (in), then the database would still be accordingly (to
OSPF), and, this route (the /32) should be filtered from the route table.
Correct?
Dave
-----Original Message-----
From: Scott Morris
To: Schulz, Dave; nobody@groupstudy.com; ''Aleksander Klessa' ';
ccielab@groupstudy.com
Sent: 7/4/2005 2:48 PM
Subject: RE: ISDN ODC Area 0 - cant use "no peer neighobr-route"
How would you apply that? OSPF rules are that everyone in the area
needs to
have an identical database... So if I generate an LSA I have to tell
you
about it (causing the dial). You can filter if from appearing in your
routing table but must appear in the database.
You're on the right track since we're talking about the /32... But how
would I stop the route from being generated to begin with as an LSA?
Scott
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Schulz, Dave
Sent: Monday, July 04, 2005 2:03 PM
To: Scott Morris ; nobody@groupstudy.com; 'Aleksander Klessa' ;
ccielab@groupstudy.com
Subject: RE: ISDN ODC Area 0 - cant use "no peer neighobr-route"
Interesting question! I'll just throw this out as a
possibility....since we
are looking to stop anything with a /32 route (peer route), would it
make
sense to use a prefix list, and deny any routes in the dialer list with
a 32
bit mask?
Dave
-----Original Message-----
From: nobody@groupstudy.com
To: 'Aleksander Klessa'; ccielab@groupstudy.com
Sent: 7/4/2005 10:53 AM
Subject: RE: ISDN ODC Area 0 - cant use "no peer neighobr-route"
Since you're thinking about "no peer neighbor-route" you know what is
causing the flap. So think about the solution.
What causes the dial is an LSA change. What LSA is changing (be very
specific)???
Now, why would either router be generating the LSA in question? What
command causes a router to generate an LSA?
Now, think about making this command more specific so the LSA in
question
doesn't ever get generated.
POOF! No flapping.
;)
Scott
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Aleksander Klessa
Sent: Monday, July 04, 2005 4:41 AM
To: ccielab@groupstudy.com
Subject: ISDN ODC Area 0 - cant use "no peer neighobr-route"
hi GS,
i have an isdn connectivity between 2 routers. the isdn network is in
Area
0. i cant use "no peer neighbor-route" and should avoid continous link
flaps.
the problem is that both routers install the remote IP ADDR as a
connected
and with disconnect they remove that from routing table.
any idea???
olo
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