Deutsche Telekom FTTH Access with OpenWRT

ftth_openwrt.md

Configuring Deutsche Telekom FTTH Access with OpenWRT

After looking for alternatves to the suggested Router from Telekom (AVM FritzBox and HUawei Speedport), I've discovered the possibility of configuring my existing OpenWRT Router to act as gateway to the Telekom FTTH (Fiber To The Home) Magenta Zuhause package.

TL;DR

The WAN interface must be configured as follows (see your Telekom letter):

• Protocol: PPPoE
• PAP/CHAP username:
  • Zugangsnummern with 12+ Digits/Chars: [email protected]
  • Zugangsnummern with less than 12 Digits/Chars: AnschlusskennungZugangsnummer#[email protected]
• PAP/CHAP password: Zugangskenntwort
• VLAN: 7
• MTU: leave empty (delete the default value 1500)

Requirements

Access Data

Old Contracts (Before 2024)

It's important to know the following information, before attempting any connection:

• Anschlusskennung
• Zugangsnummer
• Mitbenutzernummer
• Zugangskenntwort

All the above information are typically sent by Telekom at home, when activating the Internet Access.

Newer Contracts (From 2024)

The "Easy Login" option is automatically activated for new contracts. If it is activated, you can use any username/password. Otherwise it can activated in the "Kundencenter".

Otherwise it's important to know the following information, before attempting any connection:

Anschlusskennung
Zugangsnummer
Mitbenutzernummer
Zugangskenntwort

All the above information can be found oin the "Kundencenter" at "Verträge" -> "Erweiterte Optionen" -> "Internetzugang".

Hardware

You need a OpenWRT-capable router (e.g. TP-Link Archer C7 works really well), see here for an exhaustive list of supported devices.

Make sure your Telekom Fiber Modem is working properly.

Configuration

Enable VLAN

The Telekom PPPoE access requires the VLAN-ID to be set to 7. In order to do so, you have to configure the Router Ethernet interface that refers to WAN. The configuration panel can be found under the Menu entry Network->Switch (on OpenWRT 22.03 is Network -> Devices -> Add Device Config)

In this panel, you can see a table showing the VLAN(s) configured for your Router (typically 2) and they have some comboboxes with status tagged/untagged/off. One of the VLANs configured should be configured with the following information:

Port Status	CPU (eth0)	LAN1	LAN2	LAN3	LAN4	WAN
1	tagged	untagged	untagged	untagged	untagged	off
7	tagged	off	off	off	off	tagged

In case of Routers with multiple Ethernet interfaces (e.g. TP-Link Archer C7), the panel should look like this:

Port Status	CPU (eth0)	CPU (eth0)	LAN1	LAN2	LAN3	LAN4	WAN
1	tagged	tagged	untagged	untagged	untagged	untagged	off
7	tagged	tagged	off	off	off	off	tagged

Setup WAN Interface

In the Menu entry Network->Interfaces, select the WAN interface and set the following information in the General Setup tab:

• Protocol: PPPoE
• PAP/CHAP username: [email protected]
• PAP/CHAP password: Zugangskenntwort

In the tab Physical Settings, select the interface Switch VLAN eth0.7 (the one corresponding to the VLAN-ID 7).

Beware: in case your "Zugangsnummer" has less than 12 digits, the PAP/CHAP username is in the form AnschlusskennungZugangsnummer#[email protected] (see https://telekomhilft.telekom.de/t5/Telefonie-Internet/PPPOE-Einwahl-ueber-einen-Router-herstellen/ta-p/3654990 for further details)

Performance Tuning

MTU should not be set to an MTU of 1500 in any WAN, PPPOE-WAN or VLAN 7 interface - it automatically negotiates an MTU of 1492 when dialing in. Make sure that in none of the above mentioned interfaces in the field MTU is a real value in it.

Check the /etc/config/network file or execute uci show network over ssh for any configured mtu:

config interface 'wan'
option proto 'pppoe'
option device 'eth0.7'
option username '[email protected]'
option password 'xxx'
option ipv6 'auto'

This change improves the performance with Applications/Services such as MS Teams, Speedtests and many other ones.

Happy surfing!

@madduci
Thank you so much for the documentation! You have saved from being offline multiple days.

Thanks, for information above, that helps a lot!

does anyone of you experience significantly lower speed comparing to contractual one (20Mbps instead of 200Mbps) as result of using PPPoE?

In my case its gigabit switch (Zyxel GS1900-10HP) with no significant CPU load and Gigabit GPON SFP-Type SFU (PMG3000-D20B) and I'm trying to understand where is speed "bottle-neck" coming from

will appreciate any advice/hint that could help

You are welcome!

@v01t I have a Magenta Zuhause M (50 MBit/s) Package and I get ~55 MBit/s. I have an Ubiquiti Edge Router at the moment (without OpenWRT) and i don't see any load. Have you tried other Routers?

@v01t
i have the "telekom speedport" fiber modem and using this config on a Fritz!Box 5590 connected by wan to the modem. my speeds are about the same of @madduci

@v01t
Yes, my 10 year old router is not able to exceed ~300 Mbps but I can see that the CPU is pinned > 90%.
If you do not use SQM, you can enable "Software flow offloading" in the Network->Firewall settings within Luci. If your router is mt7621 based, you could also enable "Hardware flow offloading". That should increase your speeds if the router itself is the bottleneck.

@v01t The hardware in these switches is designed for switching ethernet packets on L2. That means that the traffic does not pass through the CPU under normal circumstances, it is all handled by the switch fabric. While it certainly is possible to turn them into routers, the performance is very low as the packets now need to pass the CPU. In addition, the CPU does not have any optimizations for packet processing - something that router SoCs usually include.

Source: https://openwrt.org/supported_devices/openwrt_on_switches_faq

Had problems with MS Teams, Speedtests and many other services.

MTU should not be set to an MTU of 1500 in any WAN, PPPOE-WAN or VLAN 7 interface - it automatically negotiates an MTU of 1492 when dialing in.

It is confusing, because by default, grayed out, 1500 is in it, make sure that in none of the above mentioned interfaces in the field MTU is a real value in it.

check the /etc/config/network or uci show network over ssh for any configured mtu:

...
config interface 'wan'
option proto 'pppoe'
option device 'eth0.7'
option username '[email protected]'
option password 'xxx'
option ipv6 'auto'
...

What do I do with the WAN6 interface that exists by default?

For new contracts, you do not get "Zugangsdaten" any more. Here is an updated version:
https://gist.github.com/wanne32/f24aed93ac29e5304a0f90b01bffb809

@wanne32 thank you very much for this information! Can i add your information in this gist?

@madduci Of course.

Hello,

I am on 23.05 and trying to connect to the internet using a Linksys WRT1200AC and Draytek Vigor 130 firmware 3.8.5.1 v7 (Deutsche Telekom Version). The Internet works with another router and the same modem and credentials. The vlan tagging is enabled in the modem, unfortunately I don't get a connection. Anyone any suggestions what I need to make it work? I can not follow the steps in the ghist since my openwrt layout is different. I can not acces the vlan table that is mentioned, even if I ad an Device for the physical wan port, i can set that to wan.7 as mentioned in the comments above but don't get any connection. I also disabled vlan flagging in the modem but was not able to make it work.

This is my openwrt network config:

`
root@OpenWrt:~# cat /etc/config/network

config interface 'loopback'
option device 'lo'
option proto 'static'
option ipaddr '127.0.0.1'
option netmask '255.0.0.0'

config globals 'globals'
option ula_prefix 'fd4c:e3ef:0e64::/48'

config device
option name 'br-lan'
option type 'bridge'
list ports 'lan1'
list ports 'lan2'
list ports 'lan3'
list ports 'lan4'

config interface 'lan'
option device 'br-lan'
option proto 'static'
option ipaddr '192.168.1.1'
option netmask '255.255.255.0'
option ip6assign '60'

config device
option name 'wan'
option macaddr '62:38:e0:d9:2c:55'

config interface 'wan'
option device 'wan'
option proto 'pppoe'
option username '@t-online.de'
option password ''
option ipv6 'auto'

config interface 'wan6'
option device 'wan'
option proto 'dhcpv6'
option reqaddress 'try'
option reqprefix 'auto'
`
Edit: Why is the code block not working?