Heartbeat network requirement in Server 2012 R2

Hello all,

My question is about the heartbeat network for a Hyper-V failover cluster.  Is the heartbeat network still a strong requirement in Server 2012 R2 failover clustering?

We are (possibly) getting three new servers for a new 3-node Hyper-V cluster.  Would a heartbeat network be necessary if the primary network connection upstream (to our internal network) is highly available?  And by highly available, I mean each node will have two NICs with a total of four connections to two different network switches...

Any suggestions would be appreciated.

Thanks.