Do you really need a router?

Status
Not open for further replies.

Duck

Posts: 13   +0
Hi, I have a Linksys ADSL modem with 1 USB port and 1 Ethernet port on the back. Can I connect a switch to the ethernet port to allow many more PCs to connect to the internet? If I can then why do some people have a router between the modem and the switch? What does it do?
 
Duck said:
Can I connect a switch to the ethernet port to allow many more PCs to connect to the internet? If I can then why do some people have a router between the modem and the switch? What does it do?
a very typical setup would be
Code:
modem --- (wan side) router (lan side)--- one or more systems

you can use a switch in place of the router *IF*
  • you don't want NAT/SPI services
  • you like to perform the setup yourself

you would be wise to always use a router even if there's only one system
attached, so as to have NAT and SPI features to protect you.

a router also provides DHCP service so that your LAN systems can automatically be configured, which a switch can no provide

frankly, I have this setup
Code:
modem --- (wan side) router (lan side)--- two systems
                               +
                               +
                         a switch
                               +
                               + ---- two more systems
but this is strickly because I already had the switch AND it facilitated
the physical wiring. Notice the switch is on the LAN side and all systems
get NAT/SPI protection AND DHCP configuration services.

NAT: Network Address Translation
The public Internet is on the WAN side and your systems are on them LAN side.

This forces the router to perform tricks (which a switch or hub can not do) to ensure your LAN addresses can reach outbound but the hackers can not reach inbound.

SPI: Statefull Packet Inspection
Statefull says there is a specific sequence of events and a valid data stream
always starts in a well know condition; any data that has not started from that
condition is *known* to be bogus and the packet is discarded.
this is a very effective anti-virus, anti-trojan tool!

Conclusion: in my opinion, every hispeed broadband should be required to have a router immediatel attached to the modem.
 
There is really no technical reason why it wouldn't work.. But there are many commercial reasons :)

A hub/switch does not usually work for sharing DSL because:
a) your ISP wants you to establish a PPPoE connection (you have a username and a password for that) to get an internet connection. Your ISP allows only a single login per username.
b) your ISP will give you only one IP address. You need a routing device to share an IP.

If you have a very open-minded and a naive ISP, then a hub/switch may work (technically) - all your PCs would automagically get an IP via DHCP with no authentication required.
 
Thanks very much for that detailed reply, jobeard. I think I have NAT already because my IP address is 192.168.1.2 and that IP address would not be visible from the internet side. Having a firewall would be good so I will probably get a router even for just 1 PC like you said.

Nodsu, if I understand you correctly, I'm not trying to connect the switch to the internet. I was going to go Internet >> Modem >> Switch. So the Modem was like a gateway.
 
Duck said:
I was going to go Internet >> Modem >> Switch. So the Modem was like a gateway.
yes and no. it is the only PATH, but does not provide 'gateway services'.

go to your 'router address' via your browsed http://192.168.01./
and verify the settings. you should see DHCP enabled and a PUBLIC IP address
for the WAN that is not 192.168.*.*

if so, then your modem has a router feature built-in and the switch would work,
just no SPI.
 
ahh that makes sence. I didnt realize my modem had a router built in. Thanks for your help.
 
Status
Not open for further replies.
Back