20mbit/sec ADSL - will I need a new ADSL modem?

Discussion in 'Broadband' started by Peter, Apr 4, 2010.

  1. Peter

    Peter Guest

    I am currently running a Draytek 2900 router with an ancient Dlink
    300G+ modem.

    The modem seems to support the current 8mbit/sec downlink speed fine.

    If I need a new modem for the 20Mb downlink, then I would like to get
    one which doesn't need its ethernet MAC # configured in the router!!
    This is a right PITA and there is no good reason for it. The 300G+
    needs this done in order to talk to the router...
    Peter, Apr 4, 2010
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  2. Just get a new ROUTER.
    The Natural Philosopher, Apr 4, 2010
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  3. You can get a D-link 2640 wireless modem/router for about forty quid if
    you look around.
    Easily set-uppable and it does the trick with ADSL2+

    George Weston, Apr 4, 2010
  4. Peter

    Peter Guest

    Many thanks for the suggestion - I've ordered one...
    Peter, Apr 4, 2010
  5. It has a chipset that is compatible with Fujutsi DSLAMS? There was some
    crazy claims started by ZEN internet that lots of the Draytek devices had
    AR7 chipsets that would not work reliably. This could have been ZEN
    Vicktor Whieste, Apr 4, 2010
  6. Peter

    Peter Guest


    We are much more than 200m from the exchange. My home (ZEN) is about
    1000m and my office (Eclipse) is about 2000m. At both locations I
    currently get about 6mbits/sec down and the 448k up.

    I am in no great rush to upgrade since a faster downlink is barely
    visible given so many slow websites etc, and I am more interested in
    sourcing a backup modem in case the Dlink ones fail. The problem with
    the D-link is that one cannot do a swap-out replacement; one has to
    connect it directly to a PC first (having set the PC to a fixed IP),
    connect to the modem, query its MAC#, and then connect to the router
    (having set the PC to a dynamic IP, etc) and configure the modem's
    Mac# in the router... If I was not bothered about this messing about,
    I would buy a spare 300G+ on Ebay.
    Peter, Apr 5, 2010
  7. Peter

    Graham J Guest

    The problem with the Vigor router and the separate Vigor modem is that you
    cannot interrogate the modem for its line status (data rate, SNR margin,
    line attenuation, etc.) through the router. By contrast, if you connect
    that modem to a firewall such as the GNATbox product, you can see the the
    Modem status.

    The solution is to use any convenient ADSL router (I've used the Edimax
    AR-7084A) - configured in bridge mode. The Vigor router passes the PPP
    username & password to the Edimax router. But you can connect another
    computer to one of the Edimax LAN ports (where it get its LAN address from
    the DHCP server in the Edimax) and see the line status that way.

    So use your favourate ADSL router but configure it in bridge mode.

    Even then, the bridge mode is only really necessary if you want to set up
    VPN connections; the alternative is to set the ADSL router conventionally
    (with a different network address from the main LAN) and accept that there
    are two NAT operations. This would allow you to "see" the ADSL router
    through the Vigor. But I can see that probably the only reason you want to
    use the Vigor is to support VPN connections.
    Graham J, Apr 5, 2010
  8. Peter

    Peter Guest

    I can thus communicate with the Dlink modem though... why does that

    However, for a long time this has worked only at one of the two
    locations. The 2900 routers are configured identically, except for
    different internal network IPs (necessary for the VPN connection to
    Yes, and some other stuff which was a b*astard to configure, given my
    not very extensive understanding of subnets etc.
    Peter, Apr 5, 2010
    Vicktor Whieste, Apr 5, 2010
  10. Peter

    Graham J Guest

    The Vigor router can write to syslog, but doesn't say anything useful about
    the modem, other than that it is connected or not.
    Graham J, Apr 5, 2010
  11. It appears to show some information on the LCP - but how useful that is I
    can only surmise. Looking at some of the Draytek range there is support
    for SNMP with support shown for: adslLineCoding adslLineType adslLineSpecific adslLineConfProfile adslLineAlarmConfProfile adslAturInvSerialNumber adslAturInvVendorID adslAturInvVersionNumber adslAturCurrSnrMgn adslAturCurrAtn adslAturCurrStatus adslAturCurrOutputPwr adslAturCurrAttainableRate adslAturChanInterleaveDelay adslAturChanCurrTxRate adslAturChanPrevTxRate adslAturChanCrcBlockLength

    Plus others.

    As I say - being Draytek it may only half work.
    Vicktor Whieste, Apr 5, 2010
  12. Wow, something that does not work in a Draytek? No way! I hear that soon
    they will sign a deal with 'Toys-r-us' to become their worldwide
    Vicktor Whieste, Apr 7, 2010
  13. Peter

    Graham J Guest

    The Vigor 120 is a modem, not a router. Its web interface is for its
    management. Once the modem connects to the ISP the ISP's address is
    allocated to the single connected PC - exactly as explained in the link
    you've provided. Since this is static you may have to set that into the PC.

    Despite the fact that the V120 has several LAN ports these cannot be used to
    connect more than one client machine. To do this you require an ethernet
    router (for example the Vigor 2910). Connect one WAN port of the 2910 to
    the 120 and configure its PPPoE settings as shown in the link.

    Each "bit behind the router" must have its own IP address. This will
    normally be handled by the 2910 router; and you may configure the router to
    map specific ports so specific machines. In some circumstances this will
    not work as required; in which case you will need (a block of) several
    static IP addresses from your ISP.

    Perhaps you should give us a better idea of exactly what you are trying to
    achieve. It is possible that you have not bought the correct router.
    Graham J, Apr 7, 2010
  14. Peter

    Graham J Guest

    The IP address of the modem is irrelevant other than when a single PC is
    used to configure the modem.

    The 2900 router should be set for PPPoE as shown on the documentation for
    the 2910. You provide the 2900 with the PPP username & password - this is
    passed through the V120 to the ISP.

    I have a V2930 router configured with a V120. This shows:

    Wan1 = PPPoE
    PPPoE client mode = Enable
    ISP provide username & password
    WAN connection detection = ARP detect
    MTU = 1442

    PPP/MP settings Authentication = PAPor CHAP
    IP address = Dynamic (this is important - select Dynamic even if you know it
    is static)
    Default MAC address = on

    I take it you have only one static IP address from your ISP - yes?

    Hope this helps ...
    Graham J, Apr 7, 2010
  15. Peter

    Peter Guest

    Yes, Graham, many thanks. The Draytek 120 modem is working fine, at my
    home location. It's a good solution because one could just buy a spare
    one and it should just plug in; no config.

    With PPPOE (which I never used before) I found some bizzare config
    interactions across different config pages in the 2900 router. If one
    enables PPPOE, this disables the WAN access on another page
    (understandable?). If one selects "default MAC" instead of the defined
    MAC value (no idea why I had the latter all these years**) that also
    disables PPPOE on the other page... So one has to go round a few
    times, making sure everything is enabled as required.

    Then it all worked.

    No config at all required on the modem, though I did have a look at it
    over ethernet, via a cable. No idea how to access it via the router
    though - like one can/could with the D-Link 300G+.

    (** this was a false belief that the D-Link modems required their mac
    # configured in the router, for the modem-router connection to work.
    This turned out to be bollox, and I proved it today at the office,
    where I finally configured two identical routers and two identical
    Dlink modems, so we can just swap boxes if something breaks).
    Peter, Apr 7, 2010
  16. Peter

    Peter Guest

    On a very rough test, the downlink speed I am getting with the Draytek
    120 modem is about 20%-30% higher than I was getting with the D-Link

    Thank you for your assistance.
    Peter, Apr 8, 2010
  17. Peter

    Graham J Guest

    Good work.

    I suspect the 2900 - being rather old - has some unfortunate wrinkes in its
    configuration. Might be worth upgrading its firmware ...?

    I've not found it possible to access the V120 through the V2930 router. I
    think it should be possible.

    Bear in mind that traffic crossing a router must move from one subnet to
    another. Suppose that the LAN inside the router is To
    establish communication with the modem itself, the modem on the WAN port
    should therefore be configured with a different subnet e.g.
    But ordinarily, traffic on the WAN port uses the IP address provided by the
    PPP conection to the ISP. The WAN port has this external IP address, and
    packets are carried through the modem unmodified.

    Communication between the router and the modem itself - to set up the
    connection - uses UDP rather than TCP so it has no concept of an IP address.

    Communication between the router and the modem's internal management page
    requires that the WAN port on the router has another IP address. (The modem
    might have and the router's WAN port could have This is no problem, in principle an interface can have
    several IP addresses; but in the V2900 series routers I cannot see any way
    to specify an additional IP address. I have achieved this on other routers;
    and it is then necessary to specify a route to ensure that traffic addressed
    to the external modem is delivered to the correct WAN port.

    Clearly, communication between the V2900 and the Dlink modem is different;
    but it may still be UDP.
    Graham J, Apr 8, 2010
  18. Peter

    Graham J Guest

    Pins 1,2,3,6 are all that are required for 100Mbit/sec ethernet. However
    for good noise immunity all wires should be present and connected at both
    ends of the link. If terminated at one end only, the unused wires may"
    "flap about" in the electric field and cause interference.

    Cables with only 1,2,3,6 shoule never have been made; but if they are used
    as the ***only*** cable between equipments then all will be well.
    Yours behaves differently to mine: the V2930 does not see any part of the
    V120 so things like the mamagement page with its line statistics are
    inaccessible. For that I need to connect a PC direcly to the modem.
    Graham J, Apr 8, 2010
  19. Peter

    Peter Guest

    Sorry - I meant I could access the D-Link 300G+ via the router.

    I cannot access the Draytek 120, but I have not tried exhaustively.
    Peter, Apr 8, 2010
  20. Peter

    alexd Guest

    OOI, will PPPoE still work with 21CN?
    alexd, Apr 8, 2010
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