Keep lan access even if router dies

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C.O.P.S

Occasional Visitor
So recently my Asus ac88u gave up the ghost. It was my first multi switch router. This was a rude awakening. Having all of our local traffic completely dependent upon the router means nothing works anymore. My idea is if I wire the entire local network to a managed switch, then the switch to the router, in the event of router down situation the local devices will still be able to talk to each other. Game machines can still play LAN, tv's can still stream from NAS, and so on. Correct me if I'm wrong but, would I set all the clients to use the switches IP as their gateways and set the switches gateway to the routers IP? Or am I about to embark on a mysterious and wild adventure into networking? I just want to set it up so that in the event of a router down situation the only thing the local devices lose is internet but not intranet (?).
 

L&LD

Part of the Furniture
Good Morning! :)

How you have described the new setup should work even without a managed switch. As long as you don't reboot any devices while the router is 'down'.

If you want everything to work even after a reboot and no router connected, then you will need to use manual IP addresses on all devices you want to keep connected to (i.e. not from the router, but configured from each client device instead).
 

cptnoblivious

Regular Contributor
So, what's your end goal.

Adding another single point of failure won't necessarily give you more uptime. Granted maybe you'd expect the switch to be less likely to fail.

If you have an L2 switch, from a routing perspective it should all be the same.

Things to consider:
- how long of an outage are you expecting
- do you need to have fault tolerant address assignment?
- do you need fault tolerant name resolution?

I.E. if you're going to down for days, you may want to think about DHCP and name resolution, especially if some of your devices may leave the network and come back (like cell phones or tablets).


Edit to add: I simply keep a backup router around. If the main one dies, plug it in, swap some cables, have clients change wifi network, connectivity restored. Even if my backup is older and slower, at least I'm online again within minutes.
 

ddaenen1

Senior Member
I think i am missing something here: If you would connect all your devices to a managed L2 switch and the switch to a router, i am pretty sure that if the router is down, your local devices are not talking to each other anymore. In the end, an L2 switch is not much more than the data highway and the router is the traffic warden. I think it might be possible with an L3 switch but i am not so knowledgeable about that.

I had a backup router but got rid of it. I am now running pfsense on 2 SSD drives in zraid 1. Unless some other piece of the hardware would fail, i will always be good if one SSD fails. I have a spare Supermicro server that i use to tinker. In the worst case i could get pfsense installed on that and upload the config file that pfsense backs up within the hour, i think.
 

cptnoblivious

Regular Contributor
I think i am missing something here: If you would connect all your devices to a managed L2 switch and the switch to a router, i am pretty sure that if the router is down, your local devices are not talking to each other anymore. In the end, an L2 switch is not much more than the data highway and the router is the traffic warden. I think it might be possible with an L3 switch but i am not so knowledgeable about that.

I had a backup router but got rid of it. I am now running pfsense on 2 SSD drives in zraid 1. Unless some other piece of the hardware would fail, i will always be good if one SSD fails. I have a spare Supermicro server that i use to tinker. In the worst case i could get pfsense installed on that and upload the config file that pfsense backs up within the hour, i think.

If you have devices that are all on the same LAN, they never need to contact the router for anything. I.E. they'll check their local routing table, see the destination IP is local, and ARP for the MAC of the local machine. No routing is required.

This all assumes that name resolution isn't required, or is also handled on the local network exclusively.
 

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