I have read this :
((Since BGP does not use a discernible metric value as IGPs do, the main loop prevention mechanism built into iBGP is that fact that routes learned from an iBGP neighbor cannot be advertised onto another iBGP neighbor. Therefore,
this stipulation implies that all iBGP speaking devices must establish direct peering relationships with all other iBGP devices within your autonomous system)).
I am aware that we have to have full mesh peering relations within IBGP, that means, any IBGP speaker will not pass route update to other IBGP speaker unless it has peer relationship with it . In this way, we are preventing loops from happening .
But I could not get what he mean by his comparison when he says :
“Since BGP does not use a discernible metric value as IGPs do”