What should be defined on the Edge-1 to establish valid BGP routing between agg-sw1 and...

In the design shown:

The BGP peering between agg-sw1 and agg-sw2 is being established using loopback interfaces as the BGP neighbor addresses (10.0.0.2 and 10.0.0.4)

When BGP peering uses loopbacks, you must configure the BGP session to originate updates from the same loopback interface that the neighbor’s address resolves to

Otherwise, the TCP session fails because:

The source IP does not match the configured neighbor remote-IP which is based on the loopback address

Aruba AOS-CX requirement:

“When configuring eBGP or iBGP neighbors using loopback interfaces, apply update-source under the IPv4 unicast address family so BGP uses the correct source interface for peering.”