redistributing connected routes into ospf/eigrp

acidsatyracidsatyr Senior MemberMember Posts: 111
in CCNP
Ok so here is the topology I'm running, it's pretty simple:




o
o
o
R1 R2 R3

R1 is running OSPF. R2 is running OSPF on f0/0 (interface to R1), and EIGRP on f0/1 (interface to R3). R3 is running EIGRP.
I am emulating connected interface on R2 with loopback0.
Now, when i redistribute connected into R2's router eigrp process, R3 will install a new route:

D EX 192.168.10.0/24 [170/156160] via 10.6.2.1, 00:00:05, FastEthernet0/0,

and R1 which is running OSPF will not install a route. As i imagine, this is happening because of split-horizon which
prevents R3 to send update on f0/0 on which it learned about the route to begin with.

Ok, the problem i have is, if i instead redistribute connected under R2's router ospf process, R1 will now have a route:

O E2 192.168.10.0/24 [110/50] via 10.5.2.2, 00:30:22, FastEthernet0/0,

BUT R3 will never get the update. If split horizon is not preventing R1's OSPF to advertise a route back to R2 which is using mutual redistribution, and therefore to R3
what is preventing R3 from learning about the route?

Can someone explain this to me, I'm missing a concept here ?
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  • EdTheLadEdTheLad Resident Underachiever Member Posts: 2,111 ■■■■□□□□□□
    acidsatyr wrote: »
    Ok so here is the topology I'm running, it's pretty simple:


    o
    o
    o
    R1 R2 R3

    R1 is running OSPF. R2 is running OSPF on f0/0 (interface to R1), and EIGRP on f0/1 (interface to R3). R3 is running EIGRP.
    I am emulating connected interface on R2 with loopback0.
    Now, when i redistribute connected into R2's router eigrp process, R3 will install a new route:

    D EX 192.168.10.0/24 [170/156160] via 10.6.2.1, 00:00:05, FastEthernet0/0,

    and R1 which is running OSPF will not install a route. As i imagine, this is happening because of split-horizon which
    prevents R3 to send update on f0/0 on which it learned about the route to begin with.
    Redistribute connected is performed on R2, this route is being injected into eigrp.Yes split horizon doesnt allow the route to be sent back to R2 but this is irrelavent.Even if split horizon was disabled the connected route on R2 would take priority over an eigrp route due to AD.Even if the redistributed directly connected route was feedback from R3 and had priority over the directly connected route, it wouldn't be learned by R1 as R1 is running ospf, you havent mentioned redistributing eigrp into ospf on R2.
    acidsatyr wrote: »
    Ok, the problem i have is, if i instead redistribute connected under R2's router ospf process, R1 will now have a route:

    O E2 192.168.10.0/24 [110/50] via 10.5.2.2, 00:30:22, FastEthernet0/0,

    BUT R3 will never get the update. If split horizon is not preventing R1's OSPF to advertise a route back to R2 which is using mutual redistribution, and therefore to R3
    what is preventing R3 from learning about the route?

    Can someone explain this to me, I'm missing a concept here ?

    As before, eigrp and ospf are different routing protocols that do not exchange routes unless explicitly configured to do so using redistribute.
    Networking, sometimes i love it, mostly i hate it.Its all about the $$$$
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  • acidsatyracidsatyr Senior Member Member Posts: 111
    I mentioned that R2 is using mutual redistribution, so eigrp is begin redistributed into ospf, and ospf into eigrp.


    But i've come to realize what the problem was. Thx anyway
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