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 Post subject: New Gigabit 8-port switch, no Internet for most PCs
PostPosted: Tue Feb 16, 2010 5:14 pm 
8086
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I've had a Home network for maybe 4 years now but I'm not very knowledgable on how they work. Or, I thought I was until now!

Before I purchased my Linksys Gigabit 8-Port Workgroup Switch, my network consisted of a Linksys Wireless G 2.4 GHz Router connected to a Motorola Cable modem. I just purchased a NAS Device and a Western Digital WD TV Live so now I need more than the 4 network cable ports on the Wireless Router.

I couldn't get an Internet connection (or visibilty to my network shared folders) on three PC's when I connected them to the new 8-port switch. The following is the configuration I was forced to use for Internet Connectivity:

These are connected to the 8-port switch:
- Cable modem, wireless router, my main PC

These are connected to my wireless router with cable:
- Media PC, PC #3, PC#4

These are connected to my wireless (no Cable):
- 3 Laptops

Here is what I have:
- Internet connection on all PCs
- The PC's connected to the wireless Router can share files
- My Main PC connected to the 8-Port switch has no visibility to my Media PC or any Shared folder on the PCs connected to the wireless router. It is now isolated from a network standpoint.
- I'm not getting the benefit from the 8-ports or the Gigabit switch.

Here is what I planned to have with the new switch:
- Connect all non-wireless PC's to the 8-port switch and they all have Internet connectivity and full network sharing
- Wireless router connected to the 8-Port switch with Internet connectivity for all wireless PCs and Network Sharing

Could someone walk me through what I have to do to make my "plan" happen?

Thanks, Greg


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 Post subject:
PostPosted: Tue Feb 16, 2010 5:45 pm 
Bitchin' Fast 3D Z8000
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You want your wireless router feeding your switch.

If you do nothing else, your network should act the same as before. not accounting for the NAS or media deivce.


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 Post subject:
PostPosted: Tue Feb 16, 2010 6:11 pm 
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Something's seriously amiss here.

If I understand your config correctly, the router's WAN port is NOT directly connected to the cable modem.

[cable modem]<--wire-->[giga switch]<--wire-->(wan)[wireless router]

Remember, the router makes a DHCP request that's intended to reach the ISP for resolution (w/ a public IP). But by having an intermediary like the switch, it's POSSIBLE that request could be answered by another DHCP server on the same switch. Granted this is unlikely since (at least based on what I know so far) there are no other DHCP servers. But this is the kind of thing that can come back to bite you later should you introduce a DHCP server, perhaps from another wireless router/AP you drop off that same switch. Even worse (and more likely), it's possible that some other device off that switch making a DHCP request (for a local IP) may get in ahead of the router and get itself assigned the public IP rather than the router!!! In fact, this explains why the main PC can’t see the other PCs or devices off the giga switch; the main PC is on the WAN side of the router and therefore the router’s firewall is denying access. I don’t even know how the main PC received its local IP assignment since if your ISP is like most, it only allows the one public IP, which should be assigned to the wireless router.

What you should be doing is this:

[cable modem]<--wire-->(wan)[wireless router](lan)<--wire-->[giga switch]

Bottomline, do not under any circumstances place the switch between the router and cable modem. Make it a DIRECT connection. Otherwise you're just asking for trouble.

Now you can hang your wired devices off either the 10/100mbps switch of the router, or the giga switch, as you see fit. For reasons of optimal speed, you’ll obviously want to hang Gigabit devices off the giga switch. But regardless of which switch, any wired or wireless devices will now be able to see each other.


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 Post subject:
PostPosted: Tue Feb 16, 2010 6:35 pm 
Hired Gun
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Like explained already, it needs to go Modem, Router then Switch. If it's connected that way check the IP Address on all the computers to make sure they have an IP address in the same sub net, for example 192.168.1.x, the first 3 octets should be the same, the last one should be unique for each computer or device.


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 Post subject:
PostPosted: Tue Feb 16, 2010 8:20 pm 
Million Club [PC]*
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Quote:
- My Main PC connected to the 8-Port switch has no visibility to my Media PC or any Shared folder on the PCs connected to the wireless router. It is now isolated from a network standpoint.
That's correct. Correct, because this:
Quote:
Here is what I planned to have with the new switch:
- Connect all non-wireless PC's to the 8-port switch and they all have Internet connectivity and full network sharing
- Wireless router connected to the 8-Port switch with Internet connectivity for all wireless PCs and Network Sharing
is backwards.
Modem --> router --> switch = correct
Modem --> switch --> router = not correct (and, VeryVeryBad, as it directly exposes to the internet all machines connected to the switch.)
Quote:
- I'm not getting the benefit from the 8-ports or the Gigabit switch.
Only because it's on the wrong side of the router.

A switch is a 'dumb' device - it's used solely to add ports to your wired LAN (in other words, it's used to add LAN ports to your router.) Fix your config issue (and, reboot each of the mis-connected machines), and it'll all JustWork. ;)
Due to the current mis-configuration, you'll also probably need to reboot your modem and router, as well.


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 Post subject: Thanks
PostPosted: Tue Feb 16, 2010 8:22 pm 
8086
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I quickly changed the "wiring" back to: Modem to Router and then to Switch. Both PC's connected to the switch lost their Internet Connection. I changed it back for now.

When I have more time (hopefully tomorrow), I will reconnect the moden to the router then router to switch and check the IP Address on each computer to make sure they have an IP address in the same sub net. As I stated, I've had a network, but I am new to all of this and trying to learn.

Thanks (in advance) for your patience.


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 Post subject:
PostPosted: Tue Feb 16, 2010 8:31 pm 
Bitchin' Fast 3D Z8000
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Look at it like this. The switch just adds more ports. You don't want to add ports to your modem, you want to add ports to your router (which ultimately is where you're getting your IPs from)


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 Post subject: Re: Thanks
PostPosted: Tue Feb 16, 2010 8:53 pm 
8086
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Joined: Tue Feb 16, 2010 10:04 am
Posts: 90
inezgre wrote:
I quickly changed the "wiring" back to: Modem to Router and then to Switch. Both PC's connected to the switch lost their Internet Connection. I changed it back for now.

When I have more time (hopefully tomorrow), I will reconnect the moden to the router then router to switch and check the IP Address on each computer to make sure they have an IP address in the same sub net. As I stated, I've had a network, but I am new to all of this and trying to learn.

Thanks (in advance) for your patience.


Once you mess up the topology as you did, you can't just rearrange the wiring and have it magically work. You got to get everything wired properly, then reboot all your devices and make sure all the PCs are using DHCP (obtain an IP address automatically). Reboot the modem, then reboot the router, then reboot all the PCs, etc.


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 Post subject:
PostPosted: Tue Feb 16, 2010 9:40 pm 
Million Club [PC]*
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If rebooting the 'now-broken' PCs doesn't fix them (there is actually a good chance that it won't), you'll need to do a little fixing of their network stacks.
All Windows versions, XP and later: open a command prompt (for Vista and Win7, an Elevated (Adminstrator) prompt), and run the following:
Code:
netsh int ip reset C:\resetlog.txt
and reboot.
This command will reset the TCP/IP stack to a 'virgin' state. Clears up a good many oddities that arise from a network change such as happened here.

On an XP system, you can run a Repair on the network adapter (in Network Connections), and it'll reset everything. Vista and Win7, though... it depends on what Windows decides is broken (XP just resets everything.) Drop to the command line, though... that JustWorks on all of them.


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 Post subject: Thank you everyone!
PostPosted: Wed Feb 17, 2010 8:20 pm 
8086
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Joined: Thu Feb 12, 2009 7:42 am
Posts: 36
Just wanted to say thank you. I made the changes you recommended and it looks like everything is working!

The Maximum PC Forum is by far the best forum for every PC question.

Thanks Again!
Greg


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 Post subject:
PostPosted: Wed Feb 17, 2010 8:50 pm 
Million Club [PC]*
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You're welcome. 8)
The on behalf of the community as a whole, I'd like to thank you for the compliment. :)


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