ip unnumbered help

Hmm... what am I missing? Maybe I'm not quite understanding this?

I'm trying to setup a simple eigrp peer using ip unnumbered across a point to point link using an ip address on a loopback for ip unnumbered. eigrp peers, but RTO goes to 5000 and no routes are advertised. eventually eigrp goodbye is sent and peer is terminated.

R1

int loopback8

ip address 1.1.1.1 255.255.255.255

int f0/0.1

ip unnumbered loopback8

encap dot1q 10

router eigrp 5

no auto-sum

network 1.0.0.0

R2

int loopback8

ip address 1.1.1.2 255.255.255.255

int f0/0.1

ip unnumbered loopback8

encap dot1q 10

router eigrp 5

no auto-sum

network 1.0.0.0

I notice if I put a static route on R1 pointing to f0/0.1 as the route to 1.1.1.2 and vice-versa then eigrp peers correctly but that doesn't seem very dynamic...