Sub network from third party in company network

[ITexpert]

Hello Guys,

I have one third party company who is sending preconfigured router(may be firewal) and then they have their own isolated network in our network.

There router(may be firewall) will connect to one of our switchport to get to internet.

They ask me for one static IP  within our subnet mask and its already provided.

My question is do i need to configure any static routes in firewall for them or it will just work as connected. What if they need VPN connection to that small sub network ?

Please advice how this scenario going to work ?

Thanks

[Joseph W. Doherty]

If they are going to use one of your existing host IPs for a NAT, you may not need to do anything.

[ITexpert]

yeah Joseph, they are going to use this IP as  NAT to go to internet.

But then how they will configure VPN without getting any information from us regarding our ISP public facing IP.  How they Byepass NAT on our firewall.

I am confuse now because they dont ask anything from us and they dont even say anything to do us.

They just ask for one static IP from our network

[ITexpert]

Sorry Joseph, 

They just ask for ISP public IP address not our IP address.