Need help troubleshooting DS-Lite tunnel behind an IPv6 router

Installing and Using OpenWrt Network and Wireless Configuration
1

Hello,

my new DSL provider uses IPv6 with DS-Lite tunnel for IPv4 support. Now, I'm trying to set up a proper Internet connectivity reusing my old hardware. Those are a Speedport Hybrid DSL router (by Telekom) and a TP-Link Achrcher C7 with OpenWRT on board. The setup looks like follows:

DSL -> Speedport -> OpenWRT (DS-Lite) -> LAN

Speedport provides an IPv6 connection to the Internet (google and co. work fine), but it offers very limited settings. Also, it is not capable of DS-Lite. So, my idea is to use OpenWRT to manage the DS-Lite. However, I am facing some troubles here.

First, my provider advertises the AFTR address on DHCP, but it 'ends' on the Speedport, so I have no access to this information. On the Internet, I found some suggestions, which seem reasonable to me. However, I cannot yet verify those since the tunnel does not work. Is there a possibility to manually or automatically request the DHCP information being behind a router/gateway? Or any other workaround on this?

Then, I cannot verify my DS-Lite setup is correct. I installed the 'ds-lite' package, but the autoconfig feature did not work properly. So, I had to set it up by my own. Using this manual, I updated the /etc/config/network to:

...

config interface 'wan'
	option proto 'dslite'
	option peeraddr '2001:1438:fff:30::1' # AFTR Address found on the Internet
	option encaplimit 'ignore'
	option tunlink 'wan6'

config interface 'wan6'
	option device 'eth0.2'
	option proto 'dhcpv6'
...

Afterwards, I was able to make changes to this interface on LUCI, which apparently also updates the Routing table etc. Also, I put the 'wan' interface to the firewall group of 'wan6'.

However, the DS-Lite tunnel seems not to work properly. I cannot ping any server on the internet. On LUCI, interface 'wan' shows the increasing number of RX packets, but TX counter stays at '0'. Also, there is also no 'wan6_4' interface, which, accordingly to the manual, should be created after connection.

Since I'm pretty new to OpenWRT, I would appreciate any help and any hints troubleshooting this issue.

1 Like
2

@cupora Please have a look at my answer form the linked issue. In your case, I would not use Speedport for two reasons. Reason one, it is less customizable and the other is, that it is mostly tailored for Telekom connections.

Therefore either use Fritzbox as a modem gateway and use your OpenWrt as a router or buy a Draytek modem and use your OpenWrt as a gateway. With the second option, you have to use the ds-lite package on the OpenWrt to configure the ds-lite tunnel.

As a third option, look for a Tp-Link modem router that can support German ISPs and use it in bridge mode to access it as a modem only.

Maybe as a fourth option, you can buy a FritzBox 7530 (not the ax) and install OpenWrt and access its modem functionality because this is the only FritzBox model that supports OpenWrt at the moment, as far as I know.

3

AFAIK (I've never owned a speedport myself), the speedport devices (other than the LTE 4g/ 5g hybrid ones) still offer real bridge mode, meaning they can be used as xDSL modem with the OpenWrt router terminating the PPPoE session and WAN IPv4. AVM however has removed this bridging feature several years ago, which makes them less useful as pure modem (afaik it still acts that way if completely unconfigured, but that's undocumented and relying on this behaviour is risky).

1 Like
4

Question:
Would it be possible to use the Speedport as the IPv6 Gateway and the OpenWRT with DS-Lite as the IPv4 Gateway (using the Speedport as IPv6 Gateway?)
DHCP and routing tables should allow something like this.
I tried this and have a 192.0.0.2 IP on the DS-Lite interface, but I am not able to ping the AFTR at 192.0.0.1.
Also I am not able to ping the AFTRs IPv6 address.
Will try a few things.

5

I have exactly the same issue. It seems, the setup should be valid, but it is not working for me now. I tried some things, but currently I run out ideas how to further troubleshoot the issue :frowning:

6

I have a Fritzbox (with working DS-Lite) and a speedport (with IPv6) only.

  • Connecting the Fritzbox directly to DSL works with DS-Lite.
  • Connecting the Fritzbox to the Speedport in modem mode and then to DSL works with dslite.
  • connecting the Fritzbox to the Speedport in router/gateway mode, DS-Lite on the Fritzbox does not work anymore.

Maybe the device receiving the IPv6 via DHCP from the ISP needs to be the same device that initiates the DS-Lite tunnel.
Either there is info in the DHCP response that is needed for the tunnel or the after has a whitelist of IPv6 addresses.

7

I also tested the following:

  • speedport in Modem mode + Fritzbox (ds-lite works)
  • speedport in Modem mode + openwrt (ds-lite works)
  • speedport in router mode without DSL login credentials + Fritzbox (No dslite)

So it seems the speedport does not allow pppoe passthrough and can not do DS-Lite. Very sad because the rest of the hardware is quite capable. (4x4 wifi6 160mhz, super vectoring, etc...)

I think I will switch to a 7590 ax or speedport as modem+BPI R4.

8

This seems to be the only reasonable explanation. In the meanwhile, I tried to set up a DS-Lite tunnel on my PC, but the outcome is the same. I can see packets targeted to the AFTR-Gateway, but there is no response.

Unfortunately, my Speedport Hybrid does not support modem mode, so I ended up buing a Fritzbox :frowning:

9

Same here, bought a used 7590 ax and sold the Speedport. Slower wifi but better than no IPv4.