Prolink H9601 sold by SLT(Sri Lanka Telecom) to their ADSL users did not have linux support with it.I, after many months of searching, trying, and experimenting found out the solution for it. This answer was first posted by me on LinuxQuestions.org,Ubuntu forums, and Elakiri forums.The first solutions had some problems and also amateur users could not understand properly.Also in this mehthod you dont have to keep entering eciadsl-start it normally connets on the first try.Therefore i will now post the improved version here.
1. Start by downloading and installng software.
  extact the synch.bin files to /etc/eciadsl/ as root
  Extract it to your home directory
  Open a teminal
  Enter command : cd rp-pppoe-3.10
  Enter command : sudo ./go-gui (after this command pppoe client is compiled and started.close the window       that appears after compilation)
2.Configure the drivers
1. Enter sudo eciadsl-config-text in a terminaland select the first option (configure all settings).
    Enter the information given below when asked.(Please note that the information given below are for SLT. If have a       different isp ask them for the parameters typed in bold.Remenber to type the username and password given by           your ISP.)
     VID1=0915
     PID1=8102
  VID2=0915
  PID2=8102
     MODE=LLC_SNAP_RFC1483_BRIDGED_ETH_NO_FCS
     VCI=35
  VPI=8
  FIRMWARE=/etc/eciadsl/firmware00.bin
  SYNCH=gs7470_synch20.bin
  PPPD_USER=(username)
  PPPD_PASSWD=
     USE_DHCP=no
  USE_STATICIP=no
    STATICIP=
  GATEWAY=
  MODEM=Other
  MODEM_CHIPSET=GS7470
  SYNCH_ALTIFACE=0
  PPPOECI_ALTIFACE=0
  PROVIDER=Other
     DNS1=203.115.0.46
  DNS2=203.115.0.47
2. Enter command : sudo tkpppoe
    Click "New Connection
    enter the following details in the respective tabs.
      Basic tab :
              Connection name = (put any name you want)
              Username= (given by ISP)
              Network = (not required by SLT. but put if your ISP gave you one)
              Password= (given by ISP)
      NIC and DNS tab :
              Ethernet Interface = tap0 (not included in list you will have to type it)
              DNS Setup = From Server
      Options tab:
              Click allow non-root users box and leave the others as they are.
       Advanced tab:
              leave them blank
 Click OK.
3.Connect to the Internet
1.Enter sudo eciadsl-start. keep entering this command until an error comes telling that a process called eciadsl-pppoeci is already running.
2.then type ifconfig and you must see something like this(without any rx packets):
tap0
Link encap:Ethernet HWaddr d6:ab:d9:99:f5:2e
inet6 addr: fe80::d4ab:d9ff:fe99:f52e/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:18395 errors:0 dropped:0 overruns:0 frame:0
TX packets:19493 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:500
RX bytes:17577091 (17.5 MB) TX bytes:2835186 (2.8 MB)
if you dont see something like this then keep on entering eciadsl-start again until you see it.3.Enter command : tkpppoeand click start.
 If all went right you will now be connected to the internet.                   happy surfing
-harindu perera