Question about networking in the real world

sizeonsizeon Member Posts: 321
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?

Comments

  • networker050184networker050184 Mod Posts: 11,962 Mod
    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.
    An expert is a man who has made all the mistakes which can be made.
  • sizeonsizeon Member Posts: 321
    My question is do you need to NAT even though you have a default route to the ISP router?
  • JeanMJeanM Member Posts: 1,117
    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?
    2015 goals - ccna voice / vmware vcp.
  • sizeonsizeon Member Posts: 321
    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?
  • pevangelpevangel Member Posts: 342
    An ISP will not do NAT for you.
  • networker050184networker050184 Mod Posts: 11,962 Mod
    Depends on the config. Ask the ISP.
    An expert is a man who has made all the mistakes which can be made.
  • ccnxjrccnxjr Member Posts: 304 ■■■□□□□□□□
    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!
  • sizeonsizeon Member Posts: 321
    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.
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