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ISP Configurations

This page describes how to connect to networks of different commercial Internet service providers.



A good way to configure your internet is using two devices: A dedicated modem that just accepts all ATM traffic and bridges it to its ethernet port, and a second device that acts as a router to your internal LAN, and the WAN port authenticates to your ISP via pppoe, and is physically connected to the first device over ethernet cable.

Below, I show two configs, one config for the modem, (here Netgear DM200 ADSL2+/VDSL modem) and the second config showing the necessary authentication to TPG ISP for the second device (another OpenWRT router).

package network                                                                 
config atm-bridge 'atm'                                                         
        option vpi '8'                                                          
        option vci '35'                                                         
        option encaps 'llc'                                                     
        option payload 'bridged'                                                
config dsl 'dsl'                                                                
        option annex 'a2p'                                                      
        option fwannex 'a'                                                      
        option firmware '/lib/firmware/lantiq-vrx200-a.bin'                     
        option xfer_mode 'atm'                                                  
config interface 'lan'                                                          
        option type 'bridge'                                                    
        option ifname 'eth0 nas0'                                               
        option proto 'none'                                                     
        option auto '1'                                                         
config device 'lan_dev'                                                         
        option name 'eth0'                                                      
        option macaddr 'yy.yy.yy.yy.yy.yy'                                      
config device 'wan_dev'                                                         
        option name 'nas0'                                                      
        option macaddr 'xx.xx.xx.xx.xx.xx'

Second device authenticates to ISP with:

config interface 'wan'
	option ifname 'eth1'
	option proto 'pppoe'
	option username ''
	option password 'zzzz'


Deutsche Telekom


  • ATM
    • VPI (Virtual Path Identifier): 1
    • VCI (Virtual Channel Identifier): 32
1&1 on a Telekom line with Annex J

When migrating from Annex B to Annex J, connection properties seem to have changed to require using VLAN 7.

The complete username (as opposed to the simplified form used by Fritz!Boxes '1und1/') can be obtained from a packet capture from a Fritz!Box (if internet is so far provided via one).

  • Press start on the '1. Internetverbindung'
  • Log into the main Fritz!Box UI and press the reconnect button
  • Wait until the connection is re-established
  • Stop the capture and open it in Wireshark
  • Use 'pap' as filter. You should be able to read the complete username and password in the detail view

The configuration of the interfaces should look like this (tested on r6788-7ff31bed98):

config dsl 'dsl'
	option tone 'bv'
	option annex 'j'

config interface 'wan'
	option proto 'pppoe'
	option password '***'
	option delegate '0'
	option ipv6 'auto'
	option username '1und1/(***)'
	option ifname 'dsl0.7'

config device 'wan_dev'
	option macaddr '***'
	option name 'dsl0'


The network protocols are layered in this way:

  1. VDSL link (17a profile, G.993.5 depending on the DSLAM)
  2. PTM (Packet Transfer Mode)
  3. Ethernet with VLAN 7 (data + voice)
  4. PPPoE
    1. For some resale accounts an “H” has to be added in front of the pppoe user name, for 1und1 it looks like this “H1und1/”

You global routed IPv4 address and a some IPv6 subnets

When the network supports VDSL vectoring, but the VDSL modem does not support it, the device will be put into a fall back mode using only the lower 2.2 MHz of the band, this results in reduced rates like 13 MBit/s down and 1.4 MBit/s up instead of 50 MBit/s. Details:

Example VDSL configuration for Lantiq based devices:

config dsl 'dsl'
	option annex 'a'
	option tone 'av'
	option xfer_mode 'ptm'

config interface 'wan'
	option proto 'pppoe'
	option _orig_ifname 'ptm0'
	option _orig_bridge 'false'
	option ifname 'ptm0.7'
	option username 'H1und1/'
	option password 'abcdefghijklm'
	option ipv6 'auto'
docs/guide-user/network/wan/isp-configurations.txt · Last modified: 2018/06/17 04:57 by damo22