IP addressing in the real world

control

If a company has public static addresses across its network, can these be kept if moving provider? I'd assume the company wouldn't want to reconfigure anything depending on these addresses. Are the addresses owned by the company or provider?

pcgizzmo

The IP's are usually assigned to the provider and with a new provider you will get new IP's. With my current company we've change providers at least 3 times and I have a ton of outside IP's Each time we moved I had to do the following.

Preconfigure a new or standby firewall w/the new IP's and static mappings to internal servers

Preconfigure a new or standby Internet router w/the new outside IP address.

Change your DNS entries to the lowest TTL allowed by whoever is hosting your DNS entries

On move day (Usually a weekend) I would plug in the new ISP connection to my router and test for connectivity and proper speed. Once this is done then you go and change your DNS entries over to the new IP and usually if everything is working correctly and configured properly you will roll over to the new IP's with no issues or down time. Also don't forget about MX records and if anyone is filtering your mail for SPAM like Google or Postini. Records have to be changed at MXToolbox for Postini.

This all assumes you can have dual routers and firewall and Internet connections. If you have to reuse everything then it become a bigger pain and you just have to pick a day and reconfigure everything. I always push for the dual option if I can. It makes things so much nicer.

I've done it so many times at this job and at my previous consulting job I'm a pro at it. I just to get all nervous and worried.

atorven

When we moved provider we had to get new addresses, not sure if the new provider insisted on get the new addresses from them or not.

control

Thanks for that info. when you say amend the DNS to the lowest TTL, what is the reason for this?
This is probably away from ccna, so feel free to move thread mods.

Thanks again

networker050184

Depends if they own the IP block or not.