A Little More info re: internet sharing through switch

By rokosz1 ·
Hi, folks

I'm trying to share a DSL modem in a small office. None of my cx scenarios has worked -- although, I think, I had it briefly -- because I said "bingo". but then it was gone.

This is a pretty generic set-up. But, it won't work. I've found basic answers and am currently at wits end.

The hardware:
Verizon DSL modem connects to:
Linksys WRT54G v2 via ethernet cable into "internet" port on box.

Linksys WRT54G, Dell Poweredge 400SC server and other PC workstations connect to:
Dell Powerconnect 2124 unmanaged switch.

The Lan, served by the 400SC, works fine.
the verizon DSL is unavailable.

I have tried:
Connecting a 5e Crossover cable from a std. port on the Linksys to the Poweredge in both a std. port (ie 10/100) and also the 10/100/1000 uplink port. NG.

connecting a 5e patch cable from a std. port on the Linksys to the Poweredge in both the std. port and uplink ports. NG

Can anyone shed some clear bright light on this? the IP of the router and the server are: and I get the feeling DNS/DHCP figure in this issue but don't have a clue. If you can direct me to a link or enlighten me please....


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All Answers

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what modem?

by CG IT In reply to A Little More info re: in ...

if it's those Westell 6100 ADSL2+ router/modems, the problem probably is that the modem is acting as a router. If this is the case, you have 2 routers thus 2 networks.

You'll need to turn off the router function and have it act as just a modem so that the Linksys router is your perimeter router and obtains IP address & DNS servers from Verizon on it's WAN interface.

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not really....

by ---TK--- In reply to what modem?

I run two routers at my home... My network runs just fine.

Edited to add: But if the routers are not configured correctly, that would cause an issue.

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It's your IP addresses and subnetting

by cmiller5400 In reply to A Little More info re: in ...

If you have a /24 subnet ( the IP's and will not talk to each other with out a layer 3 device in between them because they are different networks.

So here's what I'd do...

Verizon "Modem" plugs into the Linksys Wrt54G internet port - a switchport on the Linksys connects to the Dell Powerconnect 2124 switch via a cross over cable (unless one of the devices supports auto MDI/MDIX). Then everything else plugs into the Dell switch.

Make sure that you only have one network on that switch, otherwise they won't talk to each other and the Linksys router (default gateway).

Edit: Fix missing letter in mdix

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Starting on the yellow brick road...

by rokosz1 In reply to It's your IP addresses an ...

thanks, I had a feeling the IPs were (part of) the culprits.
A follow-up ?: what is a switchport? -- this particular Linksys has the "internet" port and 4 10/100s. Or is a switchport a layer 3 device? Aha. That will be new one for me.

Another ?: I've got a cross-over cable but just in case either the Dell or the Link should support MDI/MDIX -- it doesn't matter which?

I suspect the router/modem configs are ok because there've been no complaints. Earlier today I started down the DNS path trying to get the Windows2003 server to forward the two Verizon DNS IPs. That made no difference.

Please let me know and thank you,again.

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by cmiller5400 In reply to Starting on the yellow br ...

A switchport is a port in the router that acts like a switch does. It would be one of the ones marked 10/100.

A good starting point is this describes the different layers and their functions. But basically a switch is a layer 2 device. It doesn't route any packets; a layer 3 device does (router or layer 3 switch)

Try a regular cable and if you can't ping the router then try the cross over cable and see if you can ping. That will answer your question.

You will need to re-ip the network that is not on the same network as the router in order to regain internet functionality.

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Re-IP manual?

by rokosz1 In reply to Answers...

Hello M/M Cmiller,

Thanks for the clarification(s). I'd forgotten about pinging.

One final Q please? I don't understand why re-iping the non-router network (A W2003Server lan in this case) will regain I-net fx? The router, locally, is and cx'td to the Verizon DNSs.
The W23K server is Wkstns are in the family. Is that what your saying: (and now my ignorance is glaring) put the server and wkstns into the family? If so, the router and server won't conflict? And, as an aside, if not and the IP addrs are the fix, that seems to be/have been the entire issue... I'll need to take a moment.

thanks again, I hope to hear from you.

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by cmiller5400 In reply to Re-IP manual?

The 192.168.1.x network (subnet is hosting the internet connectivity. In order to connect to it, you must do one of several options.

1. Re-IP the 192.168.0.x network to the 192.168.1.x network. Depending on how your network is set up now (DHCP or static) this may or may not be easy. There are going to be conflicts that will need to be changed (the server for example.)

2. Put the 192.168.0.x network on a router and plug that router into the 192.168.1.x network and set up routing between the two. (this is going to be the more complicated method depending on what router you have/buy and your knowledge level.

3. Just change the IP address of the router to and the server to a different address.

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Thanks so much.

by rokosz1 In reply to Yes.

Thanks for the choices ala carte. I'll start with 3) and see if I'm still hungry.

This wiould be alot more fun if the risk of cutting off access for users was lower :-o. I'm more of an apps on server type...

thanks again, b

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