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So but What Modem? All's focus is on Router :(

Discussion in 'General Discussion' started by biatche, Jul 21, 2008.

  1. biatche

    biatche Network Guru Member

    I'd like to hear from experts and users their experiences with modems. I'm at this point still a little clueless of a good modem.

    I've used Netgear DG834G, Linksys AG241, Netgear DM111P, Linksys AM300, and some a little more generic brands to connect

    The above comprise of TI AR7 and BCM6338 chipsets.

    For my current setup, I turn on DMZ on the modem, but it would appear that, the NAT capability on most of them are not well tweaked, particularly when there's p2p transfer. This is with the exception of the AG241 and DG834G, as I've installed custom firmware on them.

    The AG241 issue occasionally is, it doesn't reconnect on its own. Sometimes. Not always.
    DG834G is looking good so far, but, just like the AG241, i THINK there are times it doesn't auto reconnect.. I may be wrong. and also, having a custom firmware on it, the DG834G has a major security flaw.

    All in all, it's not perfect, or at least, not perfect enough for my requirement.

    Let's hear it fellas, what modem is there, with NAT/DMZ capability, not necessarily having wireless (preferably not in fact), flawless reconnection, STABLE, and secure (less priority on this one). Try state the chipset they use as well. All in all, I don't want to see it reconnect all the time, and I don't want to have to restart it from time to time. If possible, i'd like it to stay alive for months.
  2. mstombs

    mstombs Network Guru Member

    The preferred modem is a pppoe full bridge modem, with the router handling the username/password. When this works the most common complaint is that the user cannot access the modem web screens o check logs/stats etc (but there are several ways to get round this).
    If you are in the UK or NZ (diametrically opposite on the globe!) ISPs often provide pppoa only. For this to work well with routers you get into half-bridge modes, or double nat plus dmz and there are many ways that this is implemented (or not so you have to do your own!).

    What 3rd party code do you have on your DG834, and is the AG241 Phoenix or OpenWRT?
  3. biatche

    biatche Network Guru Member

    For gods sakes, I just typed out a whole story and the site complained to me about some invalid token after clicking the post quick reply button.

    I'll keep it short so DG834 = FreeDG and other is Phoenix.

    I have 2 WAN connected to my pfsense router, which requires DMZ due to certain circumstances. This will not change. Half-bridge as I've read isn't very reliable. YMMV so please post. I do not see the benefit of half-bridge as of yet, please enlighten me.

    What is Double NAT?
  4. mstombs

    mstombs Network Guru Member

    The "modems" you refer to are actually capable of being "routers". What I mean by double nat is that the modem acts as a nat router, it keeps the ISP WAN IP and translates to a local IP address - your next router (pfsense) will then do the same again. If you have to put the pfsense router in the dmz of the modem (to enable incoming connections) then the modem must being running nat. The modem will still be "connection tracking" and suffer nat table overload etc.

    In half bridge the modem passes the WAN IP onto the router and just routes everything between the router and the ISP. Unfortunately many modem 'half bridge' implementations are poor and add extra processing to simulate the setup just hiding the fact they are routers. I believe the DM111P and AM300 have half-bridge modes in this category, look out for issues with strange netmasks, short dhcp lease times etc.

    In my modems I believe I can turn off nat completely, but still left with messy changeover should DSL drop/recover - there is no way I've found other than short lease times to communicate the fact the WAN IP has changed.
  5. biatche

    biatche Network Guru Member

    Well, i was always wondering whether i can disable the firewall/NAT on my modem(in router mode) and have DMZ enabled. as a matter of fact, as we speak right now, i had just completed configuring another DG834G and I have NAT disabled...and I will later test to see if DMZ works without firewall/NAT. I assume I will need to enable NAT. I guess my Linksys AM300 had been slow perhaps a lot due to small nat table. I think my DG834G can do more.

    I guess I'll just skip half-bridge. Sensible to me.

    Thanks for your replies. It's been a good lesson :)

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