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Linsys router and Ethernet switch

mardig88

Well-known member
Joined
Sep 5, 2011
Messages
96
Location
Montreal
Hi,

A friend asked for help setting up his connections.

He has a Linksys ethernet 8 port switch
and a cisco e3000 router.

When I connect the modem to his ethernet switch, the internet works on the computers (2 of them) that are wired to it.
But when I connect the switch to the router, the router connects to the computers but cant connect to the internet

Now if i connect the modem straight to the router, everything seems to be fine.

I checked the wires and interchanged them and made sure they are not the culprits.

Any idea on what could be wrong?

Thanks!
 

JD

Moderator
Staff member
Joined
Jul 16, 2007
Messages
9,001
Location
Toronto, ON
What switch model? If it's only 10/100Mbps, I'd only connect devices without Gigabit adapters to it.

I'd try to keep anything with a Gigabit adapter plugged into the router's LAN (Ethernet 1-4) ports, however one of those ports will need to connect to the switch, leaving you with 3 remaining ports for PC's.

Modem should be plugged into the router's WAN (Internet) port.
 

Shadowmeph

Well-known member
Joined
Oct 3, 2007
Messages
4,085
wire the switch to port 2 3 or 4 and all will be good but hook all computers to the switch
are you saying that plug into any of the outputs but not the inputs right? Some of the so called switches are not really switches which is why you need to do what enaberif is saying.
a few years back when I built a smoothwall firewall I had to do the same thing I had to plg my smoothwall( hardware firewall) into the output of my internet router before it started to work.
 

bignick277

Well-known member
Joined
May 26, 2010
Messages
173
Hi,

A friend asked for help setting up his connections.

He has a Linksys ethernet 8 port switch
and a cisco e3000 router.

When I connect the modem to his ethernet switch, the internet works on the computers (2 of them) that are wired to it.
But when I connect the switch to the router, the router connects to the computers but cant connect to the internet

Now if i connect the modem straight to the router, everything seems to be fine.

I checked the wires and interchanged them and made sure they are not the culprits.

Any idea on what could be wrong?

Thanks!
Well you shouldn't connect the modem to the switch and then the router to the switch. You should connect modem to the router and then the switch to the router. Also, if you connected your modem to the switch and then 2 computers worked and the others didn't, that surprises me unless your modem has a DHCP server on it. Which modems typically don't unless they themselves are routers. Have you set up your ip addresses manually? Switches don't do anything with ip addresses. Switches route data via Mac addresses, not ip addresses.

The reason nothing worked after connecting the router, is because the router has a dhcp server. This sets all the ip addresses of connected computers to it's own ip addressing scheme. A part of the addressing scheme would be to set the default gateway to the routers address. The default gateway in lamens terms is the address path to the internet. In other words, computers connected to the network who have all had their addresses assigned by the router are going to the router looking for access to the internet. But the internet is not connected to the WAN port on the router, therefore the router doesn't know where to send the connections to. Therefore, you don't get internet on those computers.

The way you should connect it is modem to wan on router. Then dedicate one port on router to be connected to switch and then remaining computers connected to switch. And no, don't connect the WAN port on the router to the switch, because it still won't work unless you do some heavy reconfigurations on most of your computers and on the router itself. Plus even if you did reconfigure it that way, it's far less secure than the connection method I've just described.

EDIT: Better?
 
Last edited:

enaberif

Well-known member
Joined
Dec 9, 2006
Messages
11,391
Location
Calgahree, AB
Well you shouldn't connect the modem to the switch and then the router to the switch. You should connect modem to the router and then the switch to the router. Also, if you connected your modem to the switch and then 2 computers worked and the others didn't, that surprises me unless your modem has a DHCP server on it. Which modems typically don't unless they themselves are routers. Have you set up your ip addresses manually? Switches don't do anything with ip addresses. Switches route data via Mac addresses, not ip addresses. The reason nothing worked after connecting the router, is because the router has a dhcp server. This sets all the ip addresses of connected computers to it's own ip addressing scheme. A part of the addressing scheme would be to set the default gateway to the routers address. The default gateway in lamens terms is the address path to the internet. In other words, computers connected to the network who have all had their addresses assigned by the router are going to the router looking for access to the internet. But the internet is not connected to the WAN port on the router, therefore the router doesn't know where to send the connections to. Therefore, you don't get internet on those computers. The way you should connect it is modem to wan on router. Then dedicate one port on router to be connected to switch and then remaining computers connected to switch. And no, don't connect the WAN port on the router to the switch, because it still won't work unless you do some heavy reconfigurations on most of your computers and on the router itself. Plus even if you did reconfigure it that way, it's far less secure than the connection method I've just described.
L2P please.

Modems being released with a lot of providers are now routers with wifi so that is why it probably worked.
 

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