Question about networking in the real world

When routing to the internet do you configure a default route to the ISP's router or do you have create the static route and NAT it?

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networker050184

Not sure exactly what you are asking, but unless you use a dynamic protocol (usually BGP when connecting to the internet) you will need a static default route to the internet NAT or not.

sizeon

My question is do you need to NAT even though you have a default route to the ISP router?

JeanM

Depends on the config? But most likely your local office/branch would be behind edge/asa and then nat/pat ? Is that what you are asking?

sizeon

But why do you need NAT when the ISP router is on premise? wouldnt you just configure a static route for the next hop ip which is the ISP router? And the ISP router will NAT for you?

pevangel

An ISP will not do NAT for you.

networker050184

Depends on the config. Ask the ISP.

ccnxjr

Depends on your setup.
Will people on the local LAN require access to anything outside?
Is your local lan using private IPs ?
If users on your local lan are using private ip addresses, and require access to the public internet , there will need to be a nat mapping the inside IP's and ports to a public IP/port on your router (or gateway or whatever device actually has a public IP)
This is a common setup.

However, if all the nodes within your network have public IP addresses, then no NAT is required.
Less common (but not unusual).

The deal with NAT/PAT is that you only have one(or just a few) publicly routable IP address and it has to serve the needs of several private IP addressed nodes.
It's generally the responsibility of the business /end user to have a NAT/PAT solution, as the ISP will just give you a public IP address and it's up to you to decide how to use it.
Thats why for small business/homes they'll also supply a router that's already configured to automatically perform NAT/PAT for any devices connected to the "LAN" ports.

If every device that requires public internet access has a publicly routable IP address , then NAT/PAT it isn't needed.
Which is one of the benefits of migrating to IPv6 , substantial amounts of publicly routeable IP addresses!

sizeon

ccnxjr wrote: »

Depends on your setup.
Will people on the local LAN require access to anything outside?
Is your local lan using private IPs ?
If users on your local lan are using private ip addresses, and require access to the public internet , there will need to be a nat mapping the inside IP's and ports to a public IP/port on your router (or gateway or whatever device actually has a public IP)
This is a common setup.

However, if all the nodes within your network have public IP addresses, then no NAT is required.
Less common (but not unusual).

The deal with NAT/PAT is that you only have one(or just a few) publicly routable IP address and it has to serve the needs of several private IP addressed nodes.
It's generally the responsibility of the business /end user to have a NAT/PAT solution, as the ISP will just give you a public IP address and it's up to you to decide how to use it.
Thats why for small business/homes they'll also supply a router that's already configured to automatically perform NAT/PAT for any devices connected to the "LAN" ports.

If every device that requires public internet access has a publicly routable IP address , then NAT/PAT it isn't needed.
Which is one of the benefits of migrating to IPv6 , substantial amounts of publicly routeable IP addresses!

Thanks, this answered my question.