I'm really glad someone tested it! Your results mean that we aren't losing
our minds. Just one question, did you misspeak here:
"When I issued the same command while the
router was configured without the static it indicated it was being
learned via 10.1.1.1 and being redistributed into ospf."
You don't mean redistributed, do you? It's part of the OSPF database in
this case, isn't it? Just want to make sure we're on the same page. Thanks.
Priscilla
At 11:20 PM 11/7/00, Frank B. wrote:
> Jenny & "da group",
>
> Like many of you I'm studying for the lab--big date(s) are
>21/22 June. This one caught my eye so I attempted to duplicate it as
>best I could...I set up the following lab:
>
> RTR~D<--serial-->RTR~A<--Eth-->RTR~B<--Eth-->RTR~C
> 2500 2500 7507 2500
> Aera 1 Area 1/0 Area0 Area 0/2
>
> RTR~D
> interface Ethernet0
> ip address 50.0.0.1 255.0.0.0
> !
> interface Serial1
> ip address 10.3.3.1 255.255.255.0
> !
> router ospf 4
> network 10.3.3.0 0.0.0.255 area 1
> network 50.0.0.0 0.255.255.255 area 1
>
> RTR~A
> !
> interface Ethernet0
> ip address 10.1.1.1 255.255.255.0
> !
> interface Serial1
> ip address 10.3.3.2 255.255.255.0
> !
> router ospf 1
> network 10.1.1.0 0.0.0.255 area 0
> network 10.3.3.0 0.0.0.255 area 1
>
> RTR~B
> interface Ethernet0/0
> ip address 10.1.1.2 255.255.255.0
> !
> interface Ethernet0/2
> ip address 10.2.2.2 255.255.255.0
> !
> router ospf 1
> network 10.1.1.0 0.0.0.255 area 0
> network 10.2.2.0 0.0.0.255 area 0
>
> RTR~C
> !
> interface Ethernet0
> ip address 10.2.2.1 255.255.255.0
> !
> router ospf 69
> network 10.2.2.0 0.0.0.255 area 0
>
> ------------------------------------------------
>
> I was unable to duplicate the problem...I did verify that the 7507
>(RTR~B) removed the inter-area for 50.0.0.0 from it's routing table
>route learned via RTR~A when configured with the static route--as
>expected. However, the LSA was passed to RTR~C under both
>configurations.
>
> While the static was configured I issued "sh ip route 50.0.0.0" on
>RTR~B and it showed known via static and DID NOT indicate
>"redistributing via ospf X." When I issued the same command while the
>router was configured without the static it indicated it was being
>learned via 10.1.1.1 and being redistributed into ospf.
>
>I expected those results but I was curious just the same. The bottom
>line in our lab scenario above, existance of the static route only
>affected the routing table of the router on which the static was
>entered. Further, the link state database on RTR~C also appeared to have
>the same contents with both configs on RTR~B.
>
> I'm convinced this is proper behavior for ospf. If you're seeing
>something else you may very well have stumbled upon a not-so-uncommon
>IOS bug. I may have overlooked something though...it's been known to
>happen ;-) Comments are welcome. Aloha, Frank
>
> >
> > [EMAIL PROTECTED] wrote:
> > >
> > > Had a problem today that doesn't make much sense to me.
> > >
> > > Very simplified layout (hopefully not oversimplified...)
> > >
> > > RTA -- RTB -- RTC
> > >
> > > RTB gets a summary LSA for a network, call it 50.0.0.0, from RTA. This
> > summary
> > > LSA is visible with the command 'show ip ospf da su'.
> > > There is also a static route for 50.0.0.0 on RTB, with admin distance 1.
> > Not
> > > surprisingly, this overrides the OSPF route in RTB's routing table. The
> > static
> > > route is NOT redistributed into OSPF.
> > >
> > > RTB is adjacent with RTC. However the summary LSA for 50.0.0.0 does not
> > get to
> > > RTC (as shown by 'show ip ospf da su'), and RTC has no route to 50.0.0.0
> > (as
> > > shown by 'show ip ro').
> > > If the static route is taken off RTB, OSPF sends the summary LSA to RTC
> > again,
> > > and an OSPF route to 50.0.0.0 shows up in RTC's routing table.
> > >
> > > I was under the impression that routing protocols are generally 'ships in
> > the
> > > night' in their operation (in that they each work out what they consider
> > to be
> > > the best route, and then the routing process chooses between routing
> > protocols).
> > > Why does adding a static route (not redistributed) affect what LSAs OSPF
> > sends?
> > > Shouldn't RTC get sent the summary LSA even though RTB has a better
> static
> > route
> > > - how does the OSPF process on RTB even know about the existence of the
> > static
> > > route??
> > >
> > > Am I missing something really basic here?
> > > The layout is in reality rather more complex - the RTA-RTB link is in the
> > > backbone area, the RTB-RTC link is in a different area, and the summary
> > route
> > > originates from a third area. There are also redundant routers involved.
> > If
> > > you have any theories that involve complexities like this, I can give
> more
> > > detail.
> > >
> > > Ta,
> > > JMcL
> > >
> > > p.s. over in this part of the world, we have a far more popular race on
> > the
> > > first Tuesday in November, and it's got nothing to do with politics
> > (probably
> > > why it's more popular :-)
> > >
> > > _________________________________
> > > FAQ, list archives, and subscription info:
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>
>_________________________________
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________________________
Priscilla Oppenheimer
http://www.priscilla.com
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