Question about IP block from our ISP 1

[texnut]

Hello all - I have, what I believe to be, a fairly basic question. Any help is much appreciated.

We just signed a contract with a new ISP for our office and they just sent us an email with the IP Address Block details for our office.

I'm a bit confused because they gave us our IP Block address and the corresponding subnet mask, but then they gave us the following:

"ISP Router Port IP (Customer Default Gateway)" and
"Customer Router Port IP"
and the corresponding subnet mask.

Our IP Block and the "Router Port IP" blocks are separate subnets.

So, my question is this: We will be using a PIX rather than a Router to connect to the connection. What do I use the Router Port IP address for? I'm assuming our default gateway - but what about the Customer Router one?

I hope this makes sense.

Thanks all,

S

 

[senk1s]

default gateway is the LAN side interface of the router
IP address are public IPs (on the WAN side)


someone will correct me if i'm incorrect

 

[burtsbees]

Are both IP addresses public? Are you planning to NAT?

Burt

 

[texnut]

Yes, both of the subnet's I mentioned are public IP address blocks.

I'm assuming that I will simply use the IP block that they assigned us but set the gateway on our firewall to the IP in the other block - the one labeled "ISP Router Port IP (Customer Default Gateway)" ... does that make sense?

 

[texnut]

Senk1s - I don't quite understand what you're saying. Could you perhaps draw it out?

 

[jneiberger]

The ISP router IP address is simply their end of the link. The customer router IP address is your side of that link. This is entirely separate from your assigned address space.

 

[texnut]

Ok, so I think I'm getting it:

PIX outside interface IP = "Customer Router Port IP"
PIX Default GW = "ISP Router Port IP (Customer Default Gateway)"

Then, I can assign IPs out of the pool they assigned me (which is separate from the outside/gw IPs).

I guess they handle the routing necessary to connect the two.

 

[burtsbees]

What I don't understand is why more than one public IP address, and why purchase a block---do you have a dirty DMZ that needs to be accessed from the outside or something? I would think NAT/PAT would be enough these days, no matter what peoples' needs are...

Burt

 

[jneiberger]

Texnut, you have it exactly correct.

 

[texnut]

Excellent - thanks for all your feedback.

Burt - The block is just given to us (it's part of our monthly cost, nothing extra).

Also, we will be running several services out of our office across several servers.

Perhaps NAT/PAT would be enough, but I've always worked with static mappings and reserved NAT/PAT for non-service related functions.

Thanks All!