Ethernet cable splitter - Page 2

Some newer Motorola modems (like the 6120) can act as a NAT (private IP) DHCP server for multiple devices. This feature is ONLY available if there is no Internet connection. If there is an Internet connection, machines will be assigned a public address by the cable company.

@ollyteddy, read carefully before you try it.

Yes, my Uverse 2Wire HDSL modem is also a router. But the Efficient Network ADSL modem before it was not a router. Both these modems can hold public IP addresses, be the network gateway and assign DHCP addresses. So what they can do depends on the model.

Normally within one segment of an ethernet network, the maximum number of devices thus ports is 256 (0-255). The number of DHCP (dynamic host client protocol) assignments is set in the DHCP host, e.g. 50-100 yields 51 devices, 50-250 yields 201 devices etc. DHCP host function is most commonly included in a router. But some time they can be included in a modem too. In a segment, there should only be one DHCP host. So if there are multiple routers in a single segment network, DHCP function should be turned off except one host.

I assign IP address 1-10 to routers and WiFi access points, 50-100 fixed IP addresses, 100-200 for DHCP assignments, 200-220 for printers, 250+ for storage devices such as NAS.

Prior to ethernet switches, there were boxes called ethernet hubs. Once two ports are talking, other ports are basically blocked. Switches were invented to get around this road block. Internally there is a chip called switching "fabric". A 4 ports switching fabric has 4 horizontal and 4 vertical lines. Where the lines cross is a switch point. For obvious reason each port can never switch to itself. The beauty of this design is that when port 1 is connected to port 4, port 2 can be connected to port 3 without compromising traffic between other ports. Once an end device is connected to a port, the switch knows the IP address on that port and switch traffic destined to that port. Once the data had past, the cross switch goes open again and waits for the next data. This is all there is to a basic ethernet switch design.
Edited by dksc318 - 1/16/13 at 12:38am

I used my upstairs, downstairs single cable run for two 100Base-T also until changing over to gigE.

You don't have access to change the dhcp scope? Try typing your gateway address into your browser. The credentials are normally posted on the router somewhere.

Not true. Some ADSL modems are just that - modems. They will bridge the Internet traffic on to the Ethernet port but they will not route and will not support more than one directly connected PC unless they are connected to a router. That's a bit beside the point for this discussion however.

This is still a router it just isn't running NAT like mentioned above. That being said my earlier statement that if it has rj45 ports you can hook up a switch was wrong...

That's a slick modem. I have the same one. I don't see any log in credentials on the back of mine. I have a router too and never even considered using a modem as a router. As a matter of fact I've never even heard of this concept before.

Dat dere switch.... Get one.

I'm quite familar with them (have a degree in photography), been shopping there for years. My biggest problem is that usually when I need to do something, its on a Saturday! They take that stuff pretty strict though, their online store isn't even open Saturdays.

I have the same one as well. The admin page is 192.168.100.1/config.html

The DHCP routing is only available if your ISP allows multiple IPs on your account. Most only allow one at a time, but the LAN funtion could exist if you weren't connected to the internet.

Another useful reason to use a router and a modem is a basic level firewall and ping blocking

Surfboard tips

Seems to be a common misconception but not actually true. The DHCP server on the SurfBoards only come into play if your Internet is not connected/working. See my post #31 at the top of the page. Also from your link:


Granted, it should have said "Cable Broadband" and not "CATV".

There is a good chance your router supports ADSL2 and there is no reason for you to use the modem at all. I have never owned separate modem and routers(excluding 56k) and there is no reason for them to be separate except for your ISP to try and limit the number of people connected. I find it absurd that companies are still doing this.

There is a reason I run the SB6120..

I don't follow? Almost all high speed ISPs bring coax in the home. I've not seen a coax connection on a router.

How would you get from the curb to the computer otherwise?

Quoted the wrong post. If you have a coax line then you are not dealing with adsl2. There are docsis(coax) routers that you can get but most don't have this functionality built in.

Right, I understand a little more now. Learned something new. I never new there were dsl routers out there. Guess I never needed to look

Probably but the Trendnet one posted earlier costs half that.

The Trendnet's are inexpensive and have almost universally positive reviews. The 8-port one is actually amazon's best selling swtich. It seems like the obvious choice.

I have that very model (Trendnet 8-port) and have been very pleased with it.

I am not attracted to dumb switches. I'd rather buy a router and use it as a switch. If your main router dies, you always have another one to replace it. .

I have those trendnets in my network. I cannot see the reason to get a router and then disable it to act as a switch for the odd chance that your main router quits. I've never had a router, modem or switch quit in at least 15 years of wired home networking that I have been doing. I've upgraded them on my own accord but they have never quit. Not that one won't give out but just that it hasn't happened.

Yeah, but won't you need to replace your 'switch' then? Makes no sense. If you need a router buy a router. If you need a switch by a switch. If you're that paranoid about your router randomly dying and needing to replace it immediately, keep a spare around.

The Trendnet is cheaper AND has better reviews, so again, why are you even considering the Netgear?

Not sure I follow.
Basically every modern router can work as a switch, besides, there are some deals where N-routers w/USB port can be bought for $17 or so, cheaper than the switch.
Just recently I had to implement WDS between my rooms. Had I had the switch instead of the router, I'd be in trouble. With the router formerly working as a switch, I got WDS in no time.
But once again, my friend, to each his own, LOL.

It means it has no management interface. Managed switches can support multiple VLANs, configurable Quality of Service (QoS) and will provide utilisation statistics among other things.
Most home networks don't need a managed switch.

Using just the switch functionality of a router is generally a bad idea for novice users as they'll run into trouble with DHCP, uPNP and other things.

N-router with a gig switch for $17(if you see this please pm me I could use one)? If not then you are comparing to the wrong thing. You are right that most routers use switched ports for everything but the WAN port. Segmentor is right that a switch is more user-friendly though. I have seen both switches and routers die.

Exactly, if you don't know what you're doing (like you don't disable DHCP), then you're going to mess up your network.

I appreciate the thorough discussions we have on AVSForum, but this has to be one the most ridiculous ones I've ever been involved in. The OP needs an gigabit ethernet switch. I posted the most popular one on amazon, which is inexpensive and has outstanding reviews. It will work. This really isn't complicated.

This is AVS where the most in depth technical discussions are about...wire.

I have two 8-port gigabit switches. Both bought for around $20/each. No configuration. Plug and play.

I seriously doubt your $17 router has 8-port gigabit switch in it. For most ppl, like the OP, they really don't know how to disable the DHCP, UPnP and other features that will wreak havoc on their existing networks if they just use it as a switch. So, your advice in the context of thread is really a bad advice.

As for connection between rooms, I prefer Powerline adapters over anything wireless. They are just way more reliable than wifi.