re-address entire company; best practice?

[chuck007]

Hi all,

I need to re-address the entire company to a 10.x.x.x network. Management does not want double NATs for inside and outside, so we must change all IPs. Here is what I have to work with: 1200 users, 200 servers, 200 printers, and 100 misc IP devices. Equipments include: 6509 switch w/old MSM, 3640 router, PIX 515UR, and other lower performance gears... but all are Cisco. What is the best way to go about this with out too much additional investment?

My initial thoughts:

First create the new network with VLANs, route it with either the 3640, old MSM, or PIX, and NAT it on the PIX. Then I'll be free to move machines over to the new network and leave the stuborn ones to be fixed by our WEB apps people. The major problem is going to be performance. As I'm phasing this in, for some time, the users will be on the new network but still will be accessing many servers left on the old network and my 3640 router or the MSM may not handel this traffic which will most likely be more than 500Mb throughout the day.

Purchasing a new feature routing card for the 6509 may not pass the budget and leaving it to the 3640 will severly limit routing speeds to no more than 100Mb if that.

Any thoughts on how to approach this?

Thanks in advance.

--Chuck

[thisisshanky]

HI Chuck,

WHy not give secondary ip addresses for each vlan from your new 10 network and slowly change the default gateways and IP addresses of the PCs one by one.

[chuck007]

I've thought about that. But then I'll still have to route between the old and new networks with a router, right? My routers won't be able to handel the load.

[j.viola]

Instead of having the 3640 have to handle all the traffic, why not install a separate Layer 3 Switch like the 4908G-L3. It has 8 GB GBIC slots which you could use to tie into the existing network. Or the 2948G-L3 which has 2 GB ports and 48 10/100 Ethernet ports. With that you could create Etherchannel groups of 4 100MB ports for 800 MB full duplex routed VLAN links. I think the throughput on those Layer 3 switches are like 10 million packets per second and its done in hardware not software like your Router. It would also give you a path to migrate to GB ethernet backbone down the road. You might even be able to pick up a 2948G-L3 used.

[chuck007]

Investing in a new modual or another L3 switch will solve it, however greatly discoursed by management at this time due to budget limits. Will have to go this way as a last resort if no other solution is possible.

[j.viola]

You know that old saying; "Pennywise and Pound foolish" ?

A separate Layer 3 switch will give you may times the throughput of your router, believe me - I've done it!

You can pick up a 2948G-L3 on Ebay for $3000.

Good Luck and let us know how you make out.

[chuck007]

Looks like we may very well need a MLS. The 2948G-L3 is comprabale in price to the WS-C3550-12G with 10G ports and 2 10/100s. I may just push for 3550 and use it to aggregate all our traffic. Of course, all those GBICs can get expensive.