iBGP Peering in Vol 1

Dear friends,

Recently I bought  INE WBs and while I pass thru the IBGP section in Vol 1, I bit confused with the IP addresses choosen in each device to iBGP with neoghbor devices,

I want to clear out,  the neighbor IPs used in each device has choosen any particular format ?? or IS it ok to use any connected IP in all the devices ??

By using EIGRP as IGP, all devices should have connectivity. i believe it should be fine to use any IP advertised in IGP.

Kinldy advice my understanding is correct and also the format used in the workbook.

Thanks

rYs