An enterprise has domain A(CompanyA) and Domain B(CompanyB-acquired) with two way trust. Now they have a Azure subscription for Company A being used for IaaS with S2S connectivity established.
Now, If they want to have a separate account and subscriptions for Company B, do they need to setup S2S VPN again? or can used the one with Company A given their networks are talking to each other with some firewalls in between.
If they need a S2S again, what are the pre-requisites including ports?
If not then what firewall ports can be opened between networks to use the already setup S2S?
Thanks,
DJ