One of our clients have a 6509E switch to which 15 edge switches are connected via trunk links.This 6509 is connected to a 3620 WAN router to which 20 remote sites connect via Frame relay and ISDN. The connection of the 6509E to the WAN 3620 is via Vlan 2.Now EIGRP is the routing protocol used throughout (across the WAN also.).Now we have to introduce a new core switch in to the Network (for redundancy). The plan is to have a layer 2 etherchannel between the two core switches. The WAN router has just one Fast ethernet and this has to be given to two Cores. So we plan to introduce a Layer 2 switch in between. Also we would like to have a network in between the cores and only this network will be allowed on the etherchannel. All the interfaces (including the Vlan interfaces) would be made passive EXCEPT for the ones connecting the two cores (etherchannel) and the one connecting the cores to the WAN router.
We want core1 to peer with core2 and both cores should peer with the WAN router. If we do as in above paragraph, will the cores peer with each other more than once, since hellos will be seen through both the etherchannel Vlan and also Vlan connecting the cores to the WAN router? And assuming it does, will there be any issues?
Could someone please explain the best practises for the above scenario.
Thanks in advance