From: p729@xxxxxxx
Date: Fri Jun 21 2002 - 01:15:58 GMT-3
Because of the link-state nature of OSPF, the normal routing protocol filtering
commands only have a local effect:
-'distribute list in' prevent the local router from installing the filtered rou
tes into its own routing table
-'distribute list out ospf' under a different routing process prevents that rou
ting process from advertising the filtered OSPF-derived routes
-'passive-interface' prevents OSPF from running on that interface
...but the LSDB remains unaffected.
You can suppress the emission of type 3 LSAs for areas (or certain networks wit
hin an area) by using the 'area-range not-advertise' command, but this only aff
ects type 3s the local router would otherwise normally advertise, not what's "a
lready out there."
If you really want to filter LSAs, you would have to use one of the 'ospf datab
ase-filter' commands (by neighbor or interface), but I think it's an all or not
hing proposition.
Regards,
Mas Kato
https://ecardfile.com/id/mkato
============================================================
I have been able to do filtering with a distribute list in OSPF even though alo
t of books say it wont work (because the router does not get "routes" from it's
neighbors; it gets lsa's and builds it's own routing table)
It is intermittent, and I can not figure out why it works for me sometimes and
not others. I tried the IN/OUT distinction discussed in this thread and it did
not seem to be the variable. I think all the routers had the same IOS.
Is there some other hard and fast distinction of why it would or would not work
?
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