Why would you use a passive interface?
Do passive interfaces work the same in all protocols? IE RIP, OSPF, EIGRP, BGP, IS-IS
In EIGRP I read that passive interfaces don't send any hello, acks etc.. basically doesn't participate in EIGRP at all. But the network attached to the passive interface is still advertised by other active EIGRP interfaces. Is that the same as all other routing protocols?
It is very similar to not having a network statement for the network attached to the passive interface except that the network does get advertised by other active interfaces on that router.
I know one use is when you are connected to another network that you don't want to advertise routes to.