How long can a network run without it's router?

In the scenario where Gateways, firewalls, routers, DHCP servers, DNS servers are all discrete boxes, if one pulls the router offline, most of the commonly used functions should still work, correct?  Assuming that a star distribution is in play for most of this stuff and traffic doesn't have to pass through the router to get to the other devices.

For example - if the router goes offline, and the switch has all the tables - traffic ought to flow OK except in the case where new things are trying to be accessed.

Am I on the right track here?
Azra LyndseyNerdAsked:
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JohnBusiness Consultant (Owner)Commented:
If (say) server and computers are on a switch and "in front" of the router, then yes, the router can be off line. I have had that happen and it meant no internet but internal work continued. No issue.

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Will SzymkowskiSenior Solution ArchitectCommented:
You might run into issues if you are using multiple vlans where they are configured on your router. If your router goes down then the devices on different VLAN;s will not be able to talk to each other.

As John stated you will not be able to route to any other subnets outside of your own VLAN on the switches.

Azra LyndseyNerdAuthor Commented:

If the firewall is still active, won't the the VLAN traffic still work according to the rules set in the firewall?  If I remember correctly, VLAN tags are part of the IP table, no?
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JohnBusiness Consultant (Owner)Commented:
If the VLAN is part of the switch it should work. If the VLAN is part of the router and the router is offline (off) it won't work. If the VLAN is part of the router and the router is working (but just no internet) then it should work.
Azra LyndseyNerdAuthor Commented:
Good answers to my questions.
JohnBusiness Consultant (Owner)Commented:
You are very welcome and I was happy to help.
It depends on what functions the router supplies to your LAN. Usually it is a DHCP server too, and if your system uses the router's DHCP server, your devices, when rebooted, won't get an IP.
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