Why is my loop different?

Task 4.11 is nailing me. I was verifying IGP reachablility, and had 2 addresses that wouldn't ping. I understand one, down in VL8, because of OSPF advertising it instead. So i fixed that. But the other was that damn back up link. The VLAN 52 and 5 were pingable thoughout IGP, no problem i understand. an AD of 170 goes into OSPF and turns into 110 for which other routers use as their path. OSPF is preferred over the D EX.

but its  that won't ping (in the last tcl i remember, it was from R3). But i can ping . Check out what the eigrp topology table has:

P, 1 successors, FD is 2681856
        via (2681856/2169856), Serial1/1.1
P, 1 successors, FD is 2560000256
        via Redistributed (2560000256/0)

really? a host route was coming from both router 2 and 4. I don't remember seeing anything in the solution guide about that. Yes I know they say don't worry about the backup link. BUT the backup link AND the primary are up in my case. Besides, i don't see a task saying to shut an interface on that link. So now im wondering why R3 is preferring the OSPF advertisement over the eigrp. Even stranger, the sh ip route showed it being redistributed into EIGRP. so R3 sees it with a 170 AD from the eigrp side.

Its only the 2nd core lab, so it seems im doing pretty damn terrible. Anyone seen this too?


  • At a quick look, it seems that the issue is with the PPP peer neighbor route, which diverts packets coming to 45.5 side of the link. Try disabling ppp peer neighbor route on both sides of the backup PPP link. The PPP host routes often affect optimal routing and may be the cause of lost connectivity.

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