Networking
cancel
Showing results for 
Search instead for 
Did you mean: 

Can I manually move an IP address from one server to another

Can I manually move an IP address from one server to another

We are in the process of migrating a production environment from an rx8640 to a Superdome 2. The problem is that some users access the current production by hard-coded IP address rather than a host name. I would like to re-assign that IP address to the Superdome when we cut over so that the users don't have to change IP addresses. Adding to the complexity of this, the rx8640 is on an internal '102' network (172.26.102.235) while the Superdome is on a '107' network (172.26.107.27) with a different gateway. Can I simply multiplex the 102 address onto the current 107 NIC after shutting down the rx8640?

I spoke with our network administrator about this, but he was uncertain if HPUX 11iv3 and the Superdome could support this. He said that 802.1q protocol would be required along with VLANs and trunking, none of which I understand.

 

Thanks,

Randy Knippel 

7 REPLIES
Bill Hassell
Honored Contributor

Re: Can I manually move an IP address from one server to another

I think you'll find that changing the IP address will be a lot more involved than you think. The users are easy -- just assign a new address to the new server and turn off the old box. When they can't get to the old IP, they'll have to call and get a lecture about hardcoded IP addresses. The problem in changing a server to a new address is that there are a LOT of badly coded programs that hide IP addresses in all sorts of setup and config files. HP-UX is easy to change. Fixing all the other junk will require a lot of searching. I have attached rgrep which is a script to recursively search through directories like /etc /opt /usr and /var. Use it to search for the old address in files. Some files will be logs which can ignored.

 

As far as multiple IPs for the same NIC, yes, this can be done with ifconfig. The technique is called a layered IP address. The router connected to the single NIC will need to route both networks. But a much simpler choice is to add another LAN card.



Bill Hassell, sysadmin
Dennis Handly
Acclaimed Contributor

Re: Can I manually move an IP address from one server to another

>I have attached rgrep which is a script to recursively search

 

Did you forget it?  You may have to add a suffix.

You can go back and use Edit Reply to add attachments.

Re: Can I manually move an IP address from one server to another

I think it depends on where those users using that badly coded program are.

I assume they are client program that accesses the server program running on

rx8640 at 172.26.102.235.

If those users are over a gateway (you implied this by "with a different gateway), then, I think the currently used gateway can set up NAT feature.. Here, I am assuming:

 

 

 rx8640(172.26.102.235) ------ gateway A -+-----+-------+---------+-----------

                                          |     |       |         |

                                          |  client1  client2  client3

 superdome(172.26.107.27)----- gateway B -+

 

 

If those badly coded application is running on client1/2/3 accessing rx8460

over gateway A, then, NAT configuration on gateway A (if possible) will route

all the traffic from client1/2/3 to 172.26.102.235 to 172.26.107.27, I suppose.

As rx8640 will be no longer existing, it's impossible to achieve that by some

configuration on rx8640 natually. This is clear. If gateway A continues to be

there and it has NAT feature, then, nothing has to be changed on client1/2/3.

They can communicate with superdome as if it were rx8640 at 172.26.102.235

with this way.

 

I am not so sure but even gateway B may be able to do that depending on its NAT

feature support.

 

It's worse checking the gateway's feature.

 

Re: Can I manually move an IP address from one server to another

It should be easier than that. After all Serviceguard effectively moves an IP address when it moves a package from one node to another. We already do this with a cluster of 2 rx8640's and the same 172.26.102.235 address. I guess the extra complication we have now is that the rx8640 is on a different VLAN than the Superdome. Talked more with my network guy, and I believe what he is saying is that we can do this if I can configure the Superdome NIC to communicate directly with the 2 different VLAN's. I found the HPUX VLAN Administrator's Guide and saw that this is indeed possible with even a GUI front-end via the System Management Homepage. However, my network support says he will still have to set up 'trunking' properly through the switch that the NIC is attached to. I don't understand trunking, but does this all seem reasonable?

Re: Can I manually move an IP address from one server to another

I've also proposed the NAT solution to network support. I know that we already do something similar to allow remote application vendors to connect to our systems.

Bill Hassell
Honored Contributor

Re: Can I manually move an IP address from one server to another

Sorry, I keep forgetting that the Community is Windows-based and files without the obligatory type extension are silently ignored. Here's the rgrep attachment. Feel free to rename rgrep.txt back to a more Unixy-like name such as rgrep.



Bill Hassell, sysadmin
Dennis Handly
Acclaimed Contributor

Re: Can I manually move an IP address from one server to another

>files without the obligatory type extension are silently ignored.

 

The page rejects it and blanks out the field(s).  At the very top (where I never look) is this message:

The file does not have a valid extension for an attachment. The file does not have a valid extension for an attachment. jpg,gif,pdf,png,doc,docx,ppt,pptx,xls,xlsx,zip,txt,sh,ksh,rar,pps,csv,log,ics,unl are the valid extensions.

 

So adding .sh would make the most sense.