new IP address from new subnet to a server without downtime

m4rtin

Despite the topic, this problem should be suitable for "routing and switching" forum. I have a file server which I have to move from one VLAN to other and terminate IP in other router. Currently it's on VLAN 10 and interface of the file server has IP address 192.168.10.2. New VLAN will be 20 and new IP address for file server will be 192.168.20.2.

The idea is, that currently server1 and server2 connect to file server IP address 192.168.10.2. After configuring Fa0/0 in router_planned and configuring VLAN 20 to file server, server1 and server2 should access the file server automatically with out a downtime after the file server name in DNS is changed.

Questions are, is this kind of setup possible at all? Is it possible to configure trunk port facing the file server and allow there two different VLAN's and traffic from tho different IP network at the same time?

Please find diagram here(direct link to diagram):

tiersten

Um. Why are you attempting to do this without scheduled downtime? If 100% uptime is that important to you then you wouldn't be risking this at all. If something goes bad then its going to take a lot longer to fix it on the fly than if you scheduled some time to work through it carefully.

Forsaken_GA

well if you convert the switchport to a trunk, you'd have some downtime right there, and you'd also need to configure the server to trunk.

If there's a second NIC in the server, you'd be better off hooking it up to another switch port in the proper vlan, addressing the server, and then shutting down the original port at the switch.

Honestly though, I'd just change the IP on the server, then commit that change, you'll lose connectivity, then change the vlan of the switchport, and clear arp on the new vlan for good measure. You should get connectivity back with a minimal of dropped packets

m4rtin

tiersten wrote: »

Um. Why are you attempting to do this without scheduled downtime? If 100% uptime is that important to you then you wouldn't be risking this at all. If something goes bad then its going to take a lot longer to fix it on the fly than if you scheduled some time to work through it carefully.

I don't mean that there should be no downtime at all, but it should be as small as possible. I'll schedule a maintenance window anyway.

Forsaken_GA wrote: »

well if you convert the switchport to a trunk, you'd have some downtime right there, and you'd also need to configure the server to trunk.

If there's a second NIC in the server, you'd be better off hooking it up to another switch port in the proper vlan, addressing the server, and then shutting down the original port at the switch.

Honestly though, I'd just change the IP on the server, then commit that change, you'll lose connectivity, then change the vlan of the switchport, and clear arp on the new vlan for good measure. You should get connectivity back with a minimal of dropped packets

Unfortunately there is only one physical NIC. By configuring server to trunk you mean I should configure 802.1q mode to my server interface?

peanutnoggin

Is there a reason you're hanging the server directly off the router? Is there an advantage to trunking a server port? I would put the server on a normal switchport on Switch 5, change the Vlan assignment, change the IP assignment and clear the arp table as Foresaken said for good measures. Prior to doing that... I would be sure that Switch 5 could hit the default gateway for Vlan 20 if it's going to be the router... outside of that, I think it's a fairly straightforward task you're trying to accomplish. HTH.

-Peanut

m4rtin

peanutnoggin wrote: »

Is there a reason you're hanging the server directly off the router? Is there an advantage to trunking a server port? I would put the server on a normal switchport on Switch 5, change the Vlan assignment, change the IP assignment and clear the arp table as Foresaken said for good measures. Prior to doing that... I would be sure that Switch 5 could hit the default gateway for Vlan 20 if it's going to be the router... outside of that, I think it's a fairly straightforward task you're trying to accomplish. HTH.

-Peanut

What do you mean by hanging the server directly off the router? Regarding server port trunking(setting server port to accept dot1Q frames), I thought it would give smaller downtime.
You would clear the ARP table of router_current before putting switch file server facing access port to VLAN 20?

thenjduke

You could put a second network card in the server and configure the static IP for vlan 20 and have it register with the DNS and then disable the other network card on vlan 10. Then tear down the vlan 10. You may have some down time though.

peanutnoggin

m4rtin wrote: »

What do you mean by hanging the server directly off the router? Regarding server port trunking(setting server port to accept dot1Q frames), I thought it would give smaller downtime.
You would clear the ARP table of router_current before putting switch file server facing access port to VLAN 20?

In your diagram, you have port fa0/0 on the router with the description of file server. I totally ignored the planned config for the switch's interface that lead to the server... my apologies!

Despite that, I think you should plan for at least an hour of downtime if you could... although I highly doubt you would need an hour... Add the Vlan to the switch, verify switch 2, 3, & 5 can pass Vlan 20's data via their trunk lines, verify you can reach the default router's interface, change the access Vlan to 20, then change the server's IP address. Once you do that, you should be golden! Sorry for the earlier confusion... HTH.

-Peanut

rwwest7

Trunking to the server is a bad idea, unless you have a very good reason to do it. Your other servers and clients should be connecting to the file server by hostname and not IP address, correct? If so all you should have to do is "switchport access vlan 20" on the port going to the server, then do a shut ... no shut then give the server the new IP address. It shouldn't take more than a couple minutes for the arp caches to catch up, just make sure to flush the cache on your DNS servers. So after maybe no more than 3 minutes you should be up again.

Just make sure to plug a laptop into switch 1 on vlan 20 to make sure your routing is working first before doing anything to the server.

Forsaken_GA

m4rtin wrote: »

Unfortunately there is only one physical NIC. By configuring server to trunk you mean I should configure 802.1q mode to my server interface?

Yes, and from your server interface back to the switch. Both sides have to be able to trunk. Setting up a trunk on the switch doesn't do any good if the server doesn't know what to do with packets tagged for different vlans.

Honestly though, you're better off doing just doing a proper cutover. Changing an IP on a server and changing a VLAN on a switch are relatively simple procedures and downtime should be less than a minute if you do it right.

Forsaken_GA

rwwest7 wrote: »

Trunking to the server is a bad idea, unless you have a very good reason to do it. Your other servers and clients should be connecting to the file server by hostname and not IP address, correct? If so all you should have to do is "switchport access vlan 20" on the port going to the server, then do a shut ... no shut then give the server the new IP address.

For those of you suggesting that he reconfigure the switch first and then the server, keep in mind what you're suggesting.

That will work fine if you have local access to both sets of hardware. If you are doing any of this remotely, the safe way to do it is to change the server first, then the switch. If you do it in that order, you lose contact with the server due to the IP change, but you'll get it back as soon as you change which vlan the switchport is in. If you change the switch first, you'll lose contact with the server and not be able to change it.

I've done things like this many many times, and I've always preferred to do them from the comfort of my own home than sitting on some data centers cold floor

peanutnoggin

Forsaken_GA wrote: »

For those of you suggesting that he reconfigure the switch first and then the server, keep in mind what you're suggesting.

That will work fine if you have local access to both sets of hardware. If you are doing any of this remotely, the safe way to do it is to change the server first, then the switch. If you do it in that order, you lose contact with the server due to the IP change, but you'll get it back as soon as you change which vlan the switchport is in. If you change the switch first, you'll lose contact with the server and not be able to change it.

I've done things like this many many times, and I've always preferred to do them from the comfort of my own home than sitting on some data centers cold floor

Foresaken... Good point... I had to bust out laughing as I read this! I did this today! I was in one switch and forgot that I came into that switch from a different switch... long story short, changed my IP on my client and there went my connectivity! It wasn't anything bad as I was already in the comm room, but man, I joked with another technician about the importance of understanding where you're connecting from and the adverse of effects of not knowing...

-Peanut