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WRVS4400N half-bridge mode not working

Discussion in 'Cisco Small Business Routers and VPN Solutions' started by demarchi, Mar 1, 2008.

  1. demarchi

    demarchi LI Guru Member

    I bought a WRVS4400N and an ADSL modem AM200. I was confident these were good products as they are labeled as "business".

    My Internet connection is of the PPOA type, not supported by the router. I therefore configured the modem to function as a gateway in half bridge mode to pass the connection parameters (WAN IP address, DNS and WAN default gateway) to the WRVS4400N so it can transparently connect to the Internet.

    Unfortunately this settings don't work, at least not for me: my WRVS4400N sees the WAN IP address and DNSes but NOT the default gateway so I can't connect to the Internet, although the modem works as expected. LinkSys support told me last December that this was a well known bug that would have been corrected by the next FW release. But the 1.1.06 beta doesn't fix it.

    Is there anybody that can help me with this problem before I throw the router to the bin and say goodbye to LinkSys and their products?
     
  2. mstombs

    mstombs Network Guru Member

    This is a common problem with the way Linksys and (other router makes) implement the dhcp action script - they assume the WAN gateway is in the network defined by the IP address and the netmask, which for half bridge ADSL modems is often not true. The problem can be fixed in either the modem (by spoofing the netmask or gateway) or the router (add a route command) if they run 3rd party firmware - but guess not in either the WRVS4400N or AM200 but you should look for firmware updates for both.

    Can you set a static default route in the WRVS4400N to the local modem IP?

    Edit: I have the source code for WRV4400N v1.00.15 and I can see the problem in the file called /etc/udhcpc.script, they need a "route add -host ..." between the "ifconfig ..." and "route add default gw...". They also need to remove this route when the WAN dhcp goes down or gateway changes on renew
     
  3. demarchi

    demarchi LI Guru Member

    Thanks for your reply. If I understand, the problem is quite simple to solve: the engineers at LinkSys should just add a couple of lines of code.

    Regarding the static route to the modem: if I create a static route to the modem address (modem and router are in different networks: 192.168.. the modem, 172.24.. the router) the "external" IP address in the router becomes 192.168.... So no Internet. How should I configure this static route?
     
  4. DocLarge

    DocLarge Super Moderator Staff Member Member

    Here's another option to try:

    Bridge the AM200; then set the WRVS4400N to "PPPoE." Use the username/password that your ISP gave you for your AM200 and input it into the WRVS4400N and see if the WRVS4400N will allow this.

    While I was in the UK, I used the Linksys ADSL2MUE (xDSL router/modem gateway) in bridge mode and set my WRV54G (ethernet router) to PPPoE and successfully passed internet traffic to include 5 IPSEC site-to-site vpn tunnels with no problems.

    Whereas I was able to pull this stunt with the WRV54G, I don't believe all of the Linksys routers are capable of supporting this highly inappropriate workaround (PPPoA ---> PPPoE) :) Hell, by design it shouldn't even work...but it does! :) (Go figure)

    Anyway, give it a try. If it doesn't work, then you'll know for sure the WRVS4400N doesn't support this operation, and you'll just have to input some lines.
     
  5. DocLarge

    DocLarge Super Moderator Staff Member Member

    Here's another option to try:

    Fully bridge the AM200; then set the WRVS4400N to "PPPoE." Use the username/password that your ISP gave you for your AM200 and input it into the WRVS4400N and see if the WRVS4400N will allow this.

    While I was in the UK, I used the Linksys ADSL2MUE (xDSL router/modem on a PPPoA connection) in bridge mode and set my WRV54G (ethernet router) to PPPoE and successfully passed internet traffic to include 5 IPSEC site-to-site vpn tunnels with no problems.

    Whereas I was able to pull this stunt with the WRV54G, I don't believe all of the Linksys routers are capable of supporting this highly inappropriate workaround (PPPoA ---> PPPoE) :) Hell, by design it shouldn't even work...but it does! :) (Go figure)

    Anyway, give it a try. If it doesn't work, then you'll know for sure the WRVS4400N doesn't support this operation, and you'll just have to input some lines.
     
  6. mstombs

    mstombs Network Guru Member

    This used to work because the UK incumbent BT supported PPPOE (but did not publicize it). Now there are many non-BT ISPs in UK (and NZ apparently) that are PPPOA only and this trick does not work (been there tried that...).
     
  7. mstombs

    mstombs Network Guru Member

    Assuming this is the same problem, I was able to fix it in my WRT54GS running Hyperwrt, and now Tomato, using a firewall script here:-

    http://www.linksysinfo.org/forums/showthread.php?t=52937

    I have also established that the default version of OpenWrt and dd-wrt on my fonera have the same problem and need a similar fix.

    The trouble is that you need to make this the Linux default route, and I don't know howto in your router. Is the ISP Gateway fixed (mine isn't)? If so a static route to it before the details are passed by dhcp may work.
     
  8. demarchi

    demarchi LI Guru Member

    mstombs wrote:
    I already tried this (and it was in fact the first option I thought of) but it doesn't work: my ISP (Tiscali, Italy) does not support PPOE. However, I read in a NZ forum (http://www.geekzone.co.nz/forums.asp?ForumId=49&TopicId=19132) that a similar problem was solved by LinkSys by issuing a new firmware release for the AM300 modem, which seems similar to my AM200. Unfortunately no new fw is available for the AM200 in Europe. Strange enough, the new AM300 firmware can be found in the European LinkSys server but apparently this modem is not sold this part of the World.

    Unfortunately the ISP is not fixed, so this can't work.

    Thanks anyway.
     
  9. DocLarge

    DocLarge Super Moderator Staff Member Member

    Well,

    I guess it must vary between providers. I used this "consistently" with my ISP (Hi-Velocity) up until I left this past January.

    It does work (per my own experience) based upon your ISP from the looks of things, which in your case, demarchi, is "not" the case unfortunately :(

    It looks like you'll need to start adding routes :(
     

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