This configuration it's for a very particular case on my site.
I have three links with two ISP (for example: ISP1a,ISP1b,ISP2)
I cannot annunce at the same time my entire class over ISP1a and ISP1b for two reason:
1) BGP loop problem
2) For ISP commercial reasons only one line can transport traffic at time.
Annunce my entire class over ISP1a,ISP2 with two different local preference.
Only in the case BOTH link (ISP1a,ISP2) failure, start to annunce my entire class to ISP1b.
It's possible with Palo Alto ?