How to set up IPV6 with relay bridge

Installing and Using OpenWrt Network and Wireless Configuration
1

My setup is a BT Smart Hub providing my internet connection.

I now have a LEDE BT Home Hub 5a in a separate room. This is connected wirelessly to the BT Smart Hub and I have followed the instructions to set it up as a relayd pseudobridge. I have wired clients on the LEDE router who can connect and get an IPV4 address from the BT Smart Hub in the original Subnet and access the internet and other devices across the local network without any problem.

This is working nicely for IPV4.

However IPV6 doesn't work.

The router can get an IPV6 connection and the WWAN status gives me several addresses a
Prefix Delegated: /64, Address: /64 and a Gateway: fe80.....

However, lan devices connected to the LEDE router are not able to get an appropriate IPV6 address. I can deviate from the instructions and set up hybrid mode instead of relay mode, and then they then get an address with the appropriate prefix. However there is no IPV6 connectivity to the outside.

To be honest I am finding IPV6 extremely confusing and unintuitive.

How can I set up a route via the LEDE router and on to the BT Smart Hub for the LAN clients to access IPV6?

2

You can't, relayd doesn't work with IPv6. About a year ago there were some attempts to get support for this through linux-net, but it didn't lead anywhere.
WDS/ 4addr however can pass through IPv6 subnets, but it requires mainline wlan drivers based on nl80211 on both ends.

3

So no workaround at all?

4

Any suggestions before I bite the bullet and lay some cat6?

IPv4 is working so beautifully over the pseudobridge but I feel guilty about not being IPv6 compatible...

5

Have you tried relaying IPv6 RA/NDP with odhcpd?

Edit /etc/config/dhcp

config dhcp 'lan'
	option interface 'lan'
	option start '100'
	option limit '150'
	option leasetime '12h'
	option ra 'relay'
	option ndp 'relay'

config dhcp 'wan'
	option interface 'wwan'
	option ignore '1'

config dhcp 'wan6'
	option interface 'wwan'
	option ra 'relay'
	option ndp 'relay'
	option master '1'

Then restart odhcpd via command /etc/init.d/odhcpd restart

2 Likes
6

Sorry to hijack this old thread. I'm trying to do the exact thing as the OP suggested here. I was able to config odhcpd as mentioned above. My client that is connected to the ethernet port (lan) is able to obtain an IPv6 address correctly. However, I'm not able to ping any external IPv6 hosts.

43%20AM
Screen Shot 2019-03-06 at 12.30.43 AM.png1506×720 133 KB

Topology: Client -> OpenWRT AP -> Ubiquiti UAP -> Ubiquiti USG -> Comcast

Any pointers on how to debug this further are highly appreciated.

7

I have the exact same problem (IPv6 adresses are assigned but routing isn't working). Is there really no solution for this?

8

I never got it working, just use IPv4. Causes some issues so would love to hear if anyone has the solution.

9

This worked a treat for me, just set both the incomming and out going interfaces to relay the ra and ndp packets and it worked.

10

Hi all,

just to resurrect this old thread... I wonder how it shall be configured correctly.

I do have an Archer C5 used as a Hub for Wifi and LAN connected via LAN to a Linksys WRT1900ACS. So on the Archer C5 nothing is connected to WAN interface. For the PS4 and Laptops connected to the Archer C5 to get IPv6 prefix and also stateful IPv6 addresses from the Linksys router I expected to require RA-Service, DHCPv6-Service and NDP-Proxy to be in "relay-mode". Anyhow it seems to also function when in "disabled". (Linksys has RA-Service and DHCPv6-Service in "Server mode".)

Why do I ask if everything is working? On the one hand I want to understand where relaying is needed, because I assumed it is needed. (Maybe as mentioned here, the system might automatically switches into relay mode?)
Additionally I think every now and then the whole thing breaks (devices connected to Archer C5 cannot reach internet any longer) and requires a reboot of both routers to work again. I just want to exclude an issue in the IPv6 config here.

Looking forward for feedback! :slightly_smiling_face: