CentOS - Feb 2017 - 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

On 02/13/2017 06:55 AM, KM wrote:
> 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.
That's not much to go on.  The output of "ip addr show" and
"ip route
show" might help you figure out what's going on.  Do your interfaces 
have the expected names?  Do they have the expected IP addresses?

One thing that might be problematic is that there are multiple systems 
that attempt to maintain consistent interface names.  If your interface 
names are not what you expect, you might need to look at 
/etc/udev/rules.d/70-persistent-net.rules where there may be additional 
rules mapping specific MAC addresses to an interface name.

I will get back to the mailing list.?? But to answer your questions, yes the IP
addresses and interface names are as expected (as before) with the new MAC/HW
addresses.? I have someone else looking into it because when we plugged in the
cable the light on the card did not light up.?? when we connect the pair server
to another separate server it did.? Once the server is back up I will try these
things that you suggest, and compare them to the pair server we are trying to
connect to.? We are hoping that reseating the card will work.? Probably wishful
thinking.
Thx.KM

      From: Gordon Messmer <gordon.messmer at gmail.com>
 To: CentOS mailing list <centos at centos.org> 
 Sent: Monday, February 13, 2017 12:08 PM
 Subject: Re: [CentOS] A question on networking (CentOS 6)
   
On 02/13/2017 06:55 AM, KM wrote:
> 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.
That's not much to go on.? The output of "ip addr show" and
"ip route
show" might help you figure out what's going on.? Do your interfaces 
have the expected names?? Do they have the expected IP addresses?

One thing that might be problematic is that there are multiple systems 
that attempt to maintain consistent interface names.? If your interface 
names are not what you expect, you might need to look at 
/etc/udev/rules.d/70-persistent-net.rules where there may be additional 
rules mapping specific MAC addresses to an interface name.

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