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post #1 of 9
Thread Starter 
First off, I'd like to give a somewhat formal introduction before I dive into the question. I'm a standard 19 year old male from Michigan.. attending the University of Mich - Dearborn, majoring in Networking/Network Administration (CCNA included as a cert). I work for a school district as an 'unofficial network administrator'. I say unofficial because A) I do not have a degree (yet) and B) A school district in MI can hardly afford to pay teachers, let alone a 19 year old with an "administrator" title.

With that said.. I've ran into a slight problem. My family and I have moved homes and prior to moving, we had agreed that we would wire the entire house (certain rooms) to have wired CAT5e. This would include my room upstairs (2nd story), my parents bedroom (1st story), moms office (1st story), and the basement.

I began with 1,000 ft of CAT5e from Netgear that I bought off a coworker for a decent price. I then bought a 24 port patch panel. From there, I wired the basement and currently in the process of wiring the other stories.

I tested that everything was working in the basement today... then I realized the following -


We have Comcast as an ISP. Comcast, iirc, will assign you one dynamic IP per modem. That being said, If I have a router and a switch together... there will be no connectivity.

I set up a basic configuration to confirm this... Cable modem --(WAN)--> Router --(LAN)--> Laptop will work. All is well. Cable modem --> Router --> Switch --> Laptop of course will not work. I feel that I should've recognized this before hand.

Using MAC spoofing, is there any possibility of having this setup work? I'm almost positive that there is, I'm just unsure what the answer actually is. As an option, I can always call Comcast and see what it would cost for a second IP to be assigned since two IPs -> two devices (Router, Switch) requiring them. I also thought about disabling DHCP on the router.


Below is the gear being used:


Modem - Motorola SB6121 SURFboard DOCSIS 3.0 Cable Modem
Router - Netgear WPN824N N150 Wireless Router (Pretty sure this is it.. it's at the new house and I'm not there officially until tomorrow)
Switch - Netgear ProSafe Ethernet Switch (GS116NA) ** Unmanaged
Patch Panel - TRENDnet - 24-Port Cat 5e RJ-45 UTP Rack Mountable Panel (Not like it matters)


If somebody can think of more required information, let me know. I apologize for the slur of words as it's 1:13 AM and I've been working all day, at work, and on this.


Any information would be great. Thank you.

~ Rob


** Edit: I know that the bottleneck within the home network will be the Netgear router. The LAN ports are 10/100. I had planned on using a home server running either ESXi or FreeNAS for backups and other sorts of things. I have no problem buying a new router for the 10/100/100 LAN ports if it this will end up working.
Edited by Laneo - 6/18/13 at 10:17pm
post #2 of 9
Quote:
Originally Posted by Laneo View Post


With that said.. I've ran into a slight problem. My family and I have moved homes and prior to moving, we had agreed that we would wire the entire house (certain rooms) to have wired CAT5e. This would include my room upstairs (2nd story), my parents bedroom (1st story), moms office (1st story), and the basement.

I began with 1,000 ft of CAT5e from Netgear that I bought off a coworker for a decent price. I then bought a 24 port patch panel. From there, I wired the basement and currently in the process of wiring the other stories.

I tested that everything was working in the basement today... then I realized the following -

We have Comcast as an ISP. Comcast, iirc, will assign you one dynamic IP per modem. That being said, If I have a router and a switch together... there will be no connectivity.

I set up a basic configuration to confirm this... Cable modem --(WAN)--> Router --(LAN)--> Laptop will work. All is well. Cable modem --> Router --> Switch --> Laptop of course will not work. I feel that I should've recognized this before hand.

Using MAC spoofing, is there any possibility of having this setup work? I'm almost positive that there is, I'm just unsure what the answer actually is. As an option, I can always call Comcast and see what it would cost for a second IP to be assigned since two IPs -> two devices (Router, Switch) requiring them. I also thought about disabling DHCP on the router.


If somebody can think of more required information, let me know. I apologize for the slur of words as it's 1:13 AM and I've been working all day, at work, and on this.


Any information would be great. Thank you.

~ Rob

Don't let those Michigan teachers blow smoke at you. Michigan has the #2 highest paid teacher salaries in the USA, taking cost of living into account. Here's a local article for your reading pleasure: http://www.michigancapitolconfidential.com/18265

That being said, you only need ONE Public IP address for your entire house from Comcast, and that resides on the untrusted public WAN interface on your router. The router will have an untrusted network (e.g. 192.168.0.0/255.255.0.0 on the inside, and each of your devices will pick up an address from the router via DHCP and everything should work OK.

If you're not able to use your "switch" in between the router and the workstations, check for a few important things:

1. You need all 8 wires in the patch cable between the switch and router. Gigabit Ethernet requires 8 wires to work (4 pairs) and most switches/routers have Auto MDX which will account for send/receive pairs being switched around. 100 Mbps Ethernet (100 Base-T) will run with 4 wires but is not officially supported as such. 4 unused pairs are terminated at one end to eliminate capacitance issues.

2. If your switch or router does NOT have Auto MDX, you'll need a cross-over cable. These are getting harder to find nowadays. If you don't get a link light when plugging the switch into the router, that's your most likely problem.

3. Don't disable DHCP on the router. You need it, unless you want to manually assign and manage your IP addresses on the inside of your network.

4. The proper hookup for this thing to work is:

Cable -> Cable Modem -> [patch cable] -> WAN port on Router

Then the inside network looks like this:

LAN port on Router -> [patch cable] -> Auto MDX capable port on Switch -> Computers


Don't mess around with MAC spoofing, disabling of DHCP, or any other trickery. You need NAT enabled on the router (it will be, by default, unless you disabled it). NAT will convert the private 192.168.0.x addresses on the inside private network to the Public IP on the WAN side of the router from Comcast.

Greg
Edited by hammong - 6/18/13 at 10:28pm
post #3 of 9
Thread Starter 
Thank you for the quick reply. As far as the salary.. I believe it. I work for one of the highest and quite frankly, overpaid districts in SE Michigan. I just said that mainly because the poor shape Detroit Public Schools are in.

As far as suggestion #1 -

I have checked the patch panel. When I a device into Wallport #1 which is plugged into Patch Panel #1, Switch port #1, I have link lights. I will have a connection between the home networked devices. This knocks suggestion #2 out because everything works.

The problem is that I will not have connection OUTSIDE of the house, from Comcast.

I thought that it would be pretty simple, honestly. Attach the modem to a cable line, have a patch cable running directly to the switch. This did not work. Then I thought I'll run a cable from the modem to the router. Connectivity worked. I plugged the switch into a LAN port and plugged a laptop into the switch directly.. no connectivity. Perhaps I'm missing something completely obvious here?
post #4 of 9
Quote:
Originally Posted by Laneo View Post

Thank you for the quick reply. As far as the salary.. I believe it. I work for one of the highest and quite frankly, overpaid districts in SE Michigan. I just said that mainly because the poor shape Detroit Public Schools are in.

As far as suggestion #1 -

I have checked the patch panel. When I a device into Wallport #1 which is plugged into Patch Panel #1, Switch port #1, I have link lights. I will have a connection between the home networked devices. This knocks suggestion #2 out because everything works.

The problem is that I will not have connection OUTSIDE of the house, from Comcast.

I thought that it would be pretty simple, honestly. Attach the modem to a cable line, have a patch cable running directly to the switch. This did not work. Then I thought I'll run a cable from the modem to the router. Connectivity worked. I plugged the switch into a LAN port and plugged a laptop into the switch directly.. no connectivity. Perhaps I'm missing something completely obvious here?

Cable Modem -> Router -> Switch -> Computer

That should work 100% as long as your cabling is OK and the computer picked up an IP address via DHCP.

Cable Modem -> Switch -> Computer will NEVER work. The switch connection has no MAC address on it's port, and the cable modem needs one. The cable modem will only connect to ONE MAC address. Usually it's the WAN port of a router.

Oh yeah, and power off the cable modem and router before hooking them up. The cable modem needs to be reset every time the MAC address of the device connected to it changes, e.g. router or a PC, etc.

Greg
post #5 of 9
Quote:
Originally Posted by hammong View Post

Cable Modem -> Router -> Switch -> Computer

That should work 100% as long as your cabling is OK and the computer picked up an IP address via DHCP.


Yep. This is exactly how it should work. To clarify even further:

[modem] -> [router_wan | router_lan] -> [switch] -> [PC]

router_wan will get a public IP from the ISP. router_lan/wlan should provide local private addresses to hosts via DHCP, and the router software should translate those private IPs to the public one for Internet communication.
 
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post #6 of 9
Thread Starter 
I was under the impression that everything would work. Perhaps the simple thing I did not do, which would explain why it did not work, was to unplug the modem when I did it. Silly me. I will be back at the house after work and will update the thread accordingly.. hopefully everything will work. I really would be confused if it did not work.


* Used my lunch to go check this out because curiosity was getting to me. Everything worked as it should.. I had the setup right, at one point. The only thing that stopped it from working was that I didn't unplug the modem... silly.


Thanks a lot guys.
Edited by Laneo - 6/19/13 at 8:06am
post #7 of 9
Quote:
Originally Posted by Laneo View Post

I was under the impression that everything would work. Perhaps the simple thing I did not do, which would explain why it did not work, was to unplug the modem when I did it. Silly me. I will be back at the house after work and will update the thread accordingly.. hopefully everything will work. I really would be confused if it did not work.


* Used my lunch to go check this out because curiosity was getting to me. Everything worked as it should.. I had the setup right, at one point. The only thing that stopped it from working was that I didn't unplug the modem... silly.


Thanks a lot guys.

Stupid cable modems. LOL. 99% of the time when you call Comcast, they'll ask you to unplug your modem and router, wait 30 seconds, and plug it back in. And 50% of the time, it fixes the problem. =)

Greg
post #8 of 9
Thread Starter 
You're absolutely correct. I was thinking jokingly "wow... for once unplugging my modem would've actually solved this.." I didn't consider the switch not having a MAC address per port, hence why unplugging it to set it up correctly Modem -> WAN -> LAN -> Switch was required..

Sorry for the silly inquiry.


Thanks a ton!
post #9 of 9
Actually - you should try the switch in the modem - and then cycle the modem power - technically the switch SHOULD have a mac address on each port - it is how packets get past from node to node. IP addresses are used end to end - but mac addresses are used between connected nodes.
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