ZyXEL Point-to-Point Link

Overview

By using two (now inexpensive) ZyXEL SDSL (Symmetric DSL) modems it is possible to set up an IP link between two locations with nothing more than a single copper pair. I've used two ZyXEL Prestige 782R G.SHDSL Routers which can be obtained cheaply on places like Ebay. The link speed is symetrical 2.3 Mbps.

Connecting

The first stage is to get at the serial console. I've used a no-name USB to serial adapter. The default settings of the device are 9600,8N1. Connect up the serial cable and get a console (I'll not go into that here - if you need help with that then the rest of this how-to will be of little use - sorry). When you have a working console you'll see: Bootbase Version: V2.07 | 3/15/2002 14:29:16 RAM: Size = 8192 Kbytes DRAM POST: Testing: 8192K OK FLASH: Intel 8M *2 ZyNOS Version: V2.50(BH.4) | 8/6/2002 10:56:21 Press any key to enter debug mode within 3 seconds. ............................................................ After that you'll see: Copyright (c) 1994 - 2002 ZyXEL Communications Corp. initialize ch =0, ethernet address: 00:a0:c5:c0:ff:ee Wan Channel init ............ done Press ENTER to continue... At this point press enter to get a password prompt. If you have "aquired" the device then it's likely the password will have been changed from the default "1234" (after all everyone changes the default password ;) ). If the password fails then you need to upload a new default configuration file (sometimes called a ROM). I have mirrored it. You need to dowload 250BH4C0.rom. Your terminal software needs to be able to do XMODEM. To flash the modem firstly get to the debug console - press Enter as it boots: Bootbase Version: V2.07 | 3/15/2002 14:29:16 RAM: Size = 8192 Kbytes DRAM POST: Testing: 8192K OK FLASH: Intel 8M *2 ZyNOS Version: V2.50(BH.4) | 8/6/2002 10:56:21 Press any key to enter debug mode within 3 seconds. .......... Enter Debug Mode Next get the modem ready for receiving the upload by typing 'ATLC': ATLC Starting XMODEM upload (CRC mode).... CC Next use your terminal client to upload the file in XMODEM mode (I have use Minicom): Welcome to minicom 2.6.1 OPTIONS: I18n Compiled on Feb 11 2012, 18:56:01. Port /dev/ttyUSB0 +-----------[xmodem upload - Press CTRL-C to quit]------------+ Press CTR|Sending 250BH4.bin, 8693 blocks: Give your local XMODEM recei| |ve command now. | |Bytes Sent: 16384 BPS:874 | Bootbase | | RAM: Size|Transfer complete | DRAM POST| | FLASH: In| READY: press any key to continue... | +-------------------------------------------------------------+ ZyNOS Version: V2.50(BH.4) | 8/6/2002 10:56:21 Press any key to enter debug mode within 3 seconds. ........ Enter Debug Mode ATLC Starting XMODEM upload (CRC mode).... C Total 16384 bytes received. Erasing.. .... OK As you have go this far you may as well upgrade to the latest v2.50(BH.4) if your not at it, by repeating the above but with the 250BH4.bin. This time use the 'ATUR' command.

At this point you should have two modems, running v2.50(BH.4).

Configuration

The next step is to configure the modems to act as a bridge. Label the modems 'local' and 'remote'. We'll configure the 'local' modem first. Connect to the console, and enter the password '1234' to get to the main menu: Copyright (c) 1994 - 2002 ZyXEL Communications Corp. Prestige 782R Main Menu Getting Started Advanced Management 1. General Setup 21. Filter Set Configuration 2. WAN Setup 22. SNMP Configuration 3. Ethernet Setup 23. System Password 4. Internet Access Setup 24. System Maintenance 25. IP Routing Policy Setup Advanced Applications 11. Remote Node Setup 12. Static Routing Setup 15. SUA Server Setup 99. Exit Enter Menu Selection Number: Firstly, change the system name to 'local', feel free to fill in location and contact person. Disable 'Route IP' and 'Route IPX' and enable 'Bridge': Menu 1 - General Setup System Name= local Location= Close to me Contact Person's Name= Andrew Route IP= No Route IPX= No Bridge= Yes Under menu 2, change 'Service Type' to 'Server' and 'Transfer Max Rate(Kbps)' to '2312K' and 'Transfer Min Rate(Kbps)' to '136K': Menu 2 - WAN Setup Service Type= Server Rate Adaption= Enable Transfer Max Rate(Kbps)= 2312K Transfer Min Rate(Kbps)= 136K Standard Mode= ETSI(ANNEX_B) Under menu 3, choose menu 2. In this menu set 'DHCP' to 'None'. Set 'IP Address' to '192.168.1.100' (change this of course if you need to): Menu 3.2 - TCP/IP and DHCP Ethernet Setup DHCP Setup DHCP= None Client IP Pool Starting Address= N/A Size of Client IP Pool= N/A Primary DNS Server= N/A Secondary DNS Server= N/A Remote DHCP Server= N/A TCP/IP Setup: IP Address= 192.168.1.100 IP Subnet Mask= 255.255.255.0 RIP Direction= Both Version= RIP-1 Multicast= None IP Policies= Edit IP Alias= No Under menu 11, choose menu 1. Chnage 'Route' to 'None' and 'Bridge' to 'Yes'. You can give it a better name than 'ChangeMe' if you wish: Menu 11.1 - Remote Node Profile Rem Node Name= ChangeMe Route= None Active= Yes Bridge= Yes Encapsulation= RFC 1483 Edit PPP Options= N/A Multiplexing= LLC-based Rem IP Addr= N/A Incoming: Edit IP/IPX/Bridge= No Rem Login= N/A Edit ATM Options= No Rem Password= N/A Outgoing: Session Options: My Login= N/A Edit Filter Sets= No My Password= N/A PPPoE Idle Timeout(sec)= N/A Authen= N/A PPPoE Service Name= N/A That is all that is needed for the local modem. You can of course go into menu 23 and change the password ;) For the remote, again connect up the serial console and get to the main menu. Again go into menu 1 and change the system name to 'remote', Disable 'Route IP' and 'Route IPX' ensure 'Bridge' is also set to No: Menu 1 - General Setup System Name= remote Location= Far away from me Contact Person's Name= Andrew Route IP= No Route IPX= No Bridge= No Next in menu 2 ensure 'Service Type' is set to 'Client' and 'Transfer Max Rate(Kbps)' to '2312K' and 'Transfer Min Rate(Kbps)' to '136K': Menu 2 - WAN Setup Service Type= Client Rate Adaption= Enable Transfer Max Rate(Kbps)= 2312K Transfer Min Rate(Kbps)= 136K Standard Mode= ETSI(ANNEX_B) Next in menu 3, choose menu 2, set 'DHCP' to 'None'. Set 'IP Address' to '192.168.1.101' (again change this of course if you need to): Menu 3.2 - TCP/IP and DHCP Ethernet Setup DHCP Setup DHCP= None Client IP Pool Starting Address= N/A Size of Client IP Pool= N/A Primary DNS Server= N/A Secondary DNS Server= N/A Remote DHCP Server= N/A TCP/IP Setup: IP Address= 192.168.1.101 IP Subnet Mask= 255.255.255.0 RIP Direction= Both Version= RIP-1 Multicast= None IP Policies= Edit IP Alias= No Finally, Under menu 11, choose menu 1. Chnage 'Route' to 'None' and 'Bridge' to 'Yes'. You can give it a better name than 'ChangeMe' if you wish: Menu 11.1 - Remote Node Profile Rem Node Name= ChangeMe Route= None Active= Yes Bridge= Yes Encapsulation= RFC 1483 Edit PPP Options= N/A Multiplexing= LLC-based Rem IP Addr= N/A Incoming: Edit IP/IPX/Bridge= No Rem Login= N/A Edit ATM Options= No Rem Password= N/A Outgoing: Session Options: My Login= N/A Edit Filter Sets= No My Password= N/A PPPoE Idle Timeout(sec)= N/A Authen= N/A PPPoE Service Name= N/A That should be it, connect a cable between the two xDSL sockets, power cycle both and wait for the xDSL lights to come on (~60 seconds). Connect the 'local' modems 'Lan 10/100M' socket to your network, the 'remote' modems LAN socket should now be just an extension of your network.

Note:The IP address of both modems (192.168.1.100 and 192.168.1.101 in the example above) will not be pingable, but the modems will transparently transit traffic.