12-10-2010 08:22 AM
I have an existing internet connection at work:
CDG24 cable modem in 'gateway' (their word) mode showing these configuration screen values:
WAN IP 1.2.3.88 (not a typo)
MASK 255.255.255.252
GW 1.2.3.89
Public IP 1.2.3.89/30
DNS 209.18.47.61, 209.18.47.62
Internally, this device is configured:
Gateway 192.168.1.1
MASK 255.255.255.0
DHCP enabled w/ dynamic range starting at .100
The cable provider tells me our static IP is
1.2.3.90 (not a typo -- it is NOT 89, they say)
from outside, our IP address is 1.2.3.89 when I ask any of the 'what is my ip' sites
There is a linksys WAP54G connected with the address of 192.168.1.99
There is also a hub attached for wired users.
All can access internet and internal file shares and printers
I added a RVS4000 router so I could configure a server to the DMZ as IP 1.2.3.90 and provide the internal 192.168.1.x network
I configured it's WAN this way:
Gateway 1.2.3.89
Mask 255.255.255.252
DNS 209.18.47.61, 209.18.47.62
and the LAN is factory default, at 192.168.1.1
I plugged the modem into the RVS4000 'internet' port
I plugged the hub into one of the 4 'ethernet' ports.
I powered things up and find:
PCs do get DHCP assignments with the correct DNS servers and gateway (192.168.1.1) and mask
internally I can ping to 1.2.3.89
the DNS servers cannot be queried with nslookup
in fact, it doesn't appear I can reach anything beyond the gateway. I always see 'destination unreachable'
The cable tech support said I could test the above without switching the modem into 'bridge' mode. Obviously, testing is not working.
QUESTIONS:
Do I want the RVS4000 'mode' to be 'gateway' or 'router'? (I actually intend to add a 2nd wireless WAP54G access point, thinking when I do I would have to change to router, but in the current setup leave it as 'gateway')
Is not being in 'bridge' mode on the modem causing my lack of connectivity. (But why can I then ping the cable provider's gateway)?
I should add that I set up this router on my home cable connection and was able to make it work right away. That leads me to suspect the cable company at work (different one from home) has given me incorrect IP information (such as the mystery 1.2.3.88 address).
Or have I made a mistake that (hopefully) can be gleaned from the above configuration info.
Thanks and sorry for being so long. I wanted to be as clear and accurate as possible.
12-10-2010 09:00 AM
Hi John,
You will want the RVS4000 in Gateway mode if you are not nested behind another NAT device. Putting the device in Router mode disables NAT on the WAN interface. Also, if you plan to implement port forwarding, VPN and others you will need to terminiate your WAN with a public IP address and the mode the router will need to be in is Gateway mode.
Bridge mode on the modem usually (and depends on ISP) disables their DHCP and firewall. Most times Bridge mode is used with DSL circuits so that the modem passes all data to the WAN interface. We usually do not encounter issues with a Cable modem not being in bridge mode.
What sounds most likely to me is the routing on the ISP is not correct. You can verify this by a tracert to your provided DNS server. If you see a hop to the ISP's gateway they provided (cable modem) and goes no further, or if you see one additional hop and then it fails it's most likely their routing.
One other thing to verify is that you are not having a DNS issue. See if you can ping a known IP address on the net. 4.2.2.2 and 8.8.8.8 come to mind. If you do have responses I would start looking into DNS being the cause of you not having "internet" access.
Thanks!
Dave
12-12-2010 02:29 PM
Thanks davebarre. I will try those suggestions.
John
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