[CentOS] A question on networking (CentOS 6)

Hi AllThis is NOT specifically related to CentOS per se.  I have 2 servers that are on two networks.  I did NOT set this up.  The NIC went bad and it has been replaced.  I knew enough to update the HW address in the ifcfg-* files.  The network service restarts successfully without errors.  However I cannot connect via ping or ssh with the pt2pt network setup on 192.168.x.*.  When I use our internal network ip addresses it is fine. I am not sure how to troubleshoot this separate connection.   What can I provide here that will allow someone to help?  Thanks in advance.  I tried searching a bit but didn't find anything of use so far. KM