1 modem 1 switch 2 routers. possible?

[herb]

so i have a 1000mb modem and 2 routers chained off of each other and sometimes the first router dies and then the second one doesn't work either. when this happens i have to go reset the router for it to give a signal again.

 

i just bought a simple tp link 5port switch.

 

my question is: is it possible to connect the modem to the switch FIRST then go to the 2 routers so if one dies the other one doesn't. (don't ask why i need 2 routers its a long story)

 

any help on letting me know if this will work would be appreciated.

[Radium_Angel]

2 minutes ago, herb said:

don't ask why i need 2 routers

Why do you need 2 rou....

 

sorry, you knew that was coming.

If I understand where you are coming from, and what you are asking is for the 2nd router to act as a failover when the 1st one dies...correct?

[brwainer]

It will work, IF your ISP lets you have multiple public IPs off of the modem. Usually that’s a business-level feature that you have to pay more for. The modem will usually only allow one device to get an IP address at a time, and sometimes you have to reboot the modem when changing routers.

[Windows7ge]

Only if your ISP has allotted you more than one IPv4/IPv6 address.

 

Alternatively what you can do is build a pfSense or VYoS box. In the enterprise it's very common to have a single router than manages multiple private LANs. This would make it so you only need the one Public IP your ISP likely supplies.

 

Your other option would be Double NAT and that's really not recommended.

[Nocte]

Can't you just put both routers in access point mode? (without chaining them, connect both to the modem directly)

[Lurick]

19 minutes ago, Nocte said:

Can't you just put both routers in access point mode? (without chaining them, connect both to the modem directly)

If it's just a modem such as the Arris SB8200 or Technicolor TC4400 then no as they will assign the first device that's connected and asks (via the switch) a public IP address and the rest of the devices won't get anything.

If it's a combo unit that has routing functionality built in then yes, that would work.

[eece_ret]

If you leave NAT on the Modem, and disable NAT on the routers then using static routes on the modem you should be able to route to two internal segments.  No double NAT, and you have a fully routed interior.

[eece_ret]

Also if you are simply looking for network segmentation for security or other reasons.  You could try and run two gateway interfaces off the same NAT router.   Using a managed switch you could allocate ports based on which segment you want the clients on.  Lets think an 8 port managed switch.

 

Ports 1-4 VLAN 10.  Port 1 on router defined as Segment 1 with interface 10.1.0.1, Port 1 on switch to port 1 on router.  Now ports 1-4 are segment 1 served by 10.1.0.0/24 GW 10.1.0.1.

 

Ports 5-8 VLAN 20.  Port 2 on router defined as Segment 2 with interface 10.2.0.1, Port 5 on switch to port 2 on router.  Now ports 5-8 are segment 2 served by 10.2.0.0/24 GW 10.2.0.1.

 

 

Here you could then pass teh public IP to the router and have the NAT performed there.  Or use a private network between teh router and modem and leave NAT at the modem.  Whatever makes sense for you.

 

 

 

[eece_ret]

[herb]

thank you guys for all your tips. ill let you know how it goes

[Falcon1986]

@herb

 

Why though? What are you trying to achieve?

 

And can you specify the makes/models of all the networking equipment from modem and beyond?

[TechNurd]

15 hours ago, Nocte said:

Can't you just put both routers in access point mode? (without chaining them, connect both to the modem directly)

this would be the easiest way. make you routers act like switches. you still could daisy chain them if you need the length