My ISP has issued me 59.144.abc.xyz/30 as WAN IP.I've configured the same on eth1 of RB 450G and its working fine with private Ip on eth2 in NAT mode.Now I've procured public IP block 110.172.abc.xyz/24 separately and want to configure it on eth2 in place of the private IP that I'am presently using.My ISP says I need to enable BGP and advertisement on the router to use the plublic IP block on the LAN side.The LAN side public IP series is from another ISP.Pls guide me.

Got both ISP's router AS numbers.Problems resolved.Post closed.