ETHoA in Tomato firmware?

Discussion in 'Tomato Firmware' started by moussa, Sep 17, 2010.

  1. moussa

    moussa Networkin' Nut Member

    My ISP uses ETHoA over here for their broadband which seems uncommon. Their supplied router is terrible so I bridged a WRT54GS with tomato installed to it with the ISP router running as a modem and the WRT54GS running as an access point. From what I understand this means I can't use QoS although I don't understand why? My question is can I just use the WRT54GS as the modem instead? I can't find anything resembling ETHoA in the tomato settings and I've searched endlessly on the net and these forums but haven't come up with a clear answer.

    These are the settings for the ISP if that helps
  2. mstombs

    mstombs Network Guru Member

    Tomato doesn't have an ADSL connection - it can't do the ATM bit of ETHoA. You need some form of half-bridge to run on the modem to give the ISP WAN IP to tomato for best performance, but if the modem can put the router into its DMZ you can run in double-nat mode with pretty full functionality in Tomato.
  3. moussa

    moussa Networkin' Nut Member

    Thanks for your reply. I think I'm pretty competent when it comes to computers but routers and networks really do my head in. I've been reading up and my understanding is putting my tomato router in the modems DMZ will expose my tomato router to the internet directly? If I can achieve that will I have to change anything on the tomato router? Do I have to still run the bridge on the modem? Sorry for all these questions but I'm in over my head and my home network is in desperate need of QoS!

    Edit: OK after much reading I think I understand what I need to do, thanks for pointing me in the right direction. The ISP supplied router is pretty locked down so I need to use CLI commands to put it in bridge mode. Wish me luck
  4. mstombs

    mstombs Network Guru Member

    Don't know much about that specific ISP, ADSL router or ETHoA. Seems most of the world use PPPoE, UK and NZ often use PPPoA, I think ETHoA sometimes also known as just dhcp in modem configs.

    You can only full bridge PPPoE and then use PPPoE WAN port config on the Tomato Router - this is the most transparent modem setup, and most problems are around getting access to the modem gui for stats monitoring.

    Most forms of "half-bridge" used with "oA" connections need the Tomato Router in default WAN dhcp mode. There are Draytek modems that convert PPPoA to PPPoE, and Thomson Speedtouch that will convert PPPoE to PPTP.

    Watch out there is a lot of duff info on the net re bridging modems, you can only use PPPoE full bridge if your ISP supports it. UK BT used to support PPPoE unofficially as well as PPPoA - so lots of folk thought they were full bridging PPPoA...
  5. moussa

    moussa Networkin' Nut Member

    OK I'm struggling with this. I can put the modem into bridge mode but from then on I'm stuck with how to set up the tomato on the router

    Are you saying that because Tomato can't do ETHoA I need a half bridge and not a full one? So I put the modem in half bridge mode and use DHCP in the network settings?

    Edit: I have managed to modify my modem so one of it's ethernet ports is a DMZ port. Where do I go from here?
  6. mstombs

    mstombs Network Guru Member

    Data is transferred across the ADSL link in 53 Byte (including header) ATM frames, the device that connects to the phone line needs to convert this to normal Ethernet comms (up to 1500 including header), and yours will do this by creating a virtual Ethernet port inside the modem.

    Your problem is that the modem likes to act as a router, gets its WAN IP by dhcp then with multiple lan interfaces sharing the WAN connection using nat tables etc.

    It seems pretty tricky to turn off the router in your modem, but must be a common questions?

    Ideally you will be able to get the ISP WAN IP into the Tomato router, if it has to be a local IP address you must still be running nat translation in the modem - it should work but essential to put Tomato router in the dmz of the modem for incoming port forwards to work.

    I don't think there's a standard definition of what "bridge" you need. With PPPoE, which is really PPPoEoA there is a standard way of passing on the PPPoE packets in a full bridge mode. With PPPoA the PPP decoding needs to be done on the modem and its usually known as half-bridge when just passing on the WAN IP from modem to router. Your ISP connection is close to the latter - without the overhead of PPP encryption I guess.
  7. moussa

    moussa Networkin' Nut Member

    OK after realising I made a stupid mistake (my brain is frazzled by the hours I've spent on this) the tomato router now receives an WAN IP address from the modem. The problem now is no computers on the wireless network connected to the router have internet access. In the tomato tools I can ping outside ip addresses fine, but no such luck with any computers. I have the router set as a DHCP server already but am I missing something obvious?
  8. mstombs

    mstombs Network Guru Member

    Tomato must be in "Gateway" mode not "router", this setting is hidden away on Advanced->Routing->Miscellaneous, its the default but presumably not needed in Access Point mode...
  9. moussa

    moussa Networkin' Nut Member

    Thank you very much! Everything's working nicely now :) Thanks for all your help
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