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LAN Routing Problems

Discussion in 'Cisco Small Business Routers and VPN Solutions' started by neilrmessick, Jul 19, 2005.

  1. neilrmessick

    neilrmessick Network Guru Member

    Okay... here is my config....

    Cisco 5000 Switch with built in router that handels 2 local VLANS, P2P T1 with 2 more VLAN's on that side. Right now we have DSL service thats tied into one of the P2P T1's for PPOE. This is changing to an RV042 with Cable intenet service.

    Right now, if I plug in the RV042 only the local VLAN can get though the internet.

    I have the default gateway (gateway of last resort) funneling down to the RV042. I assume that it does not know how to get back to the other VLAN subnets so I added some static routes to those networks... makes sense, and with this its possible to ping the LAN interface... but it still does not get though to the internet. After a firmware upgrade I was able to ping the RV042's WAN interface, but not the interface of the cable modem.

    I'm at a loss, I called Linksys and they say they won't support static routing... maybe cause it does not work?! I don't know. I'm at a loss. I had my CCNA about 4-5 years ago, I'm rusty.... but I'm not dumb. Seems like this should work to me.

  2. TazUk

    TazUk Network Guru Member

    Is the RV setup as a Router or Gateway?
  3. neilrmessick

    neilrmessick Network Guru Member

  4. neilrmessick

    neilrmessick Network Guru Member

    I've done some more messing with this and I can say pretty condifently that this thing has issuses. It does not seem to follow the static routes like it should. I dropped another router into exactly the same place with the same configeration and it worked right away.
  5. TazUk

    TazUk Network Guru Member

    What IP ranges are the VLAN's using?

    What's performing NAT on the network?
  6. neilrmessick

    neilrmessick Network Guru Member


    There is a VLAN router in each network thats the default gateway of all the clients. The routers are set to have a gateway of last resort (default gateway in cisco speak) pointing to the RV042.

    There is nothing doing NAT right now, although I don't quite see how that relates.
  7. TazUk

    TazUk Network Guru Member

    Well those IP ranges are non routable, from an internet point of view, so something must be performing NAT if your able to access websites, etc. It may be that the RV, or whatever, only performs NAT on addresses within it's local subnet.
  8. neilrmessick

    neilrmessick Network Guru Member

    I thought NAT was used to expose particular WAN ports to internal IP addresses. Static routing is used to direct traffic internaly.
  9. TazUk

    TazUk Network Guru Member

    NAT, (Network Address Translation), is a system for sharing a single public IP address between several PC's. It takes requests on the private IP, changes the packet with it's public IP and sends it off across the internet. When a response packet comes back it changes the address back to the private IP and forwards it on to the relevant PC. Without this you would need to have public IP's assigned to each PC that requires internet access. Port forwarding under NAT is used to direct packets coming in on a particular port to a specific PC, this is necessary as the PC's are not directly visable from the internet.

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