VMWare Backup using ESX host that has multiple IPs

Friends,

NBU Windows 7.5.0.6

Media Linux 7.5.0.6 (VMware host)

trying to backup the ESX host that has built in storage and running two vms. Host has two NICs (x.x.50.x and x.x.10.x) and the name of the host is xyz.

x.50 IP resolve to the name xyz

x.10 IP resolve to the name abc

if we backup the vm using x.50 the traffic goes through the firewall (100Mb port) hence backup is really slow. So we thought server has a free NIC lets add another vmkernal port (Gig x.10 IP) and trying to backup the vm directly. I am trying to add the ESX host using x.10 IP but login credential failed. I am trying to get the root password. So my question is it possible or have i got the completely wrong end of the stick?