Verizon DSL modem - no DHCP?

Question

If I connect my PC or laptop directly to the Verizon DSL modem, it says 'limited connectivity' on the LAN connection. So, I set up a new connection to use PPPoE, enter my username and a password (will accept anything for a password), and it connects to the Internet just fine. An ipconfig command shows the PC's IP and the gateway IP as the same address, an external 74.x.x.x address. Why is the modem not giving out an internal 192.x.x.x address? I don't want to have to 'connect' every time I want to get online.

Answer 1

Because your DSL connection is designed to use PPPoE, you can't use raw Ethernet.  That's why you get "limited connectivity" without PPPoE ... you're not recognized by the provider's aggregation router.

DSL modems aren't typically designed to do NAT (Network Address Translation) from private addresses (e.g. in the 192.168.0.0/16 range) like SOHO router/AP boxes.  Their only purpose is to provide a connection for a single host.  That's why you only get a public 74.x.x.x address, once the requirements of your PPPoE stack are satisfied.  BTW, your modem isn't serving DHCP, it's the aggregation router or something behind it.

-- Round 2:

Based on the additional information provided (which BTW, is highly unusual), I have a couple of questions:

1.  Does your modem have an integrated switch or hub?  That is, is it designed to connect to multiple hosts?

2. What exact brand/model is it?

Without answers to the above, I can only conclude that either:

i) your modem is configured differently than your neighbor's, or

ii) you are mistaken - the two modems differ in some significant way (e.g. different firmware or different provisioning by the provider)

-- Round 3:

OK, so based on your latest info, yes the Westell 6100 is a modem/router device.  Verizon offers the latest firmware here:

http://netservices.verizon.net/portal/si...

(You might want to start by making sure you have the Verizon firmware, not the generic Westell one, and that it's the latest available from Verizon.)

Here's an excerpt from a course I recently taught showing the DSL PPPoE deployment options:

http://www.dividedhighway.ca/YahooHelp/D...

From what you've reported, it does appear that your 6100 is misconfigured (as I previously guessed).  It needs to be setup to:

A. operate in PPPoE mode towards the provider (instead of Bridge mode which forces you to run PPPoE from your PC), and

B. provide DHCP of a private address (and NAT/routing) to any client PCs connected behind it

Referring to the JPG I provided to clarify ... you are currently configured as option 3, but you want to configure as option 1.  (Option 2 is when you're using an external router with a separate DLS modem.)

I neither have a 6100 nor Verizon (I'm not even located in the US), but the screens on the link below may be helpful for you to pinpoint where in the 6100 user interface to make/change these settings.

http://www.lava.net/support/Westell_6100...

(BTW, you may need to statically configure your PC temporarily so its address is in the proper subnet to administer the 6100, e.g. IP=192.168.1.2, mask=255.255.255.0, GW=192.168.1.1)

If that doesn't solve it, I suggest you phone Verizon support and get them to walk you through the settings.  In particular, only your local provider will know the details of the exact VPI/VCI settings you need, etc.

HTH,

David

CCNP-certified Networking Professor

Answer 2

All depends on the MODEM. Modems are not routers, routers will issue private IP's most modems do not, there are a few that do but most are just a bridge connector and not routing units. If you put a router between your computer and the internet modem you can put the PPPoE in the router and it will issue private addresses.

If your modem used to issue 192.x.x.x addresses and it is no longer doing that, it has been set to BRIDGE mode, sometimes you can login to the modem/router and turn that off and on.

Add: if the modem can be set to NAT  mode, go to the manufacturers website (for the Modem) and see how to turn the NAT function back on.  Yours is set to bridge, not nat! Or tell us the model and make so we can find and tell you how.

ADD:: Westell 6100 can be used either way, it would appear yours has been set to BRIDGE mode as shown in this information

http://www.lava.net/support/Westell_6100...

If you reverse that you can then use DHCP again. You just need to set a static IP on your computer to 192.168.1.10 then use your browser and type in 192.168.1.1 and set your unit back to Private Network and turn on DHCP!  That will allow you to work as you wish!  Once done, reset your computer to DHCP.

Answer 3

factory reset your adsl modem and set it up again...

should work