Here is the senario: 3560 as our CE equipment connected via fiber to PE equipment in vpls network. Running eigrp for all sites. 3560 is also connected to 6500 in our local network. Eigrp neighbors for the 3560 are the CEs at the vpls remote sites plus the 6500. If we loose connectivity to the vpls cloud on the other side of the PE hence the interface on the 3560 is still up/up toward vpls cloud, how long before the 3560 realizes there is a problem and tells the 6500 to drop the routes through him to the remote sites (all Eigrp timers are at defaults).