How to send prefix hint on wwan interface

[kb0]

I have a TRB500, configured in passthrough mode. My mobile operator by default delegates me a /64, but I would like to request a bigger prefix through a prefix hint. However, there doesn’t seem to be any way to change the requested prefix length for interfaces using the “Mobile” protocol as one can with an interface that uses the “DHCPv6” protocol.

Is there some way to do this that I’m missing, or is it simply not possible?

[Daumantas]

Hello,

This configuration is not currently possible via the WebUI, but you could try adding it via the CLI/SSH. Log into the CLI/SSH with the username root, and the same password as the webUI, and run the following commands:

uci set network.mob1s1a1.dhcpv6='1'
uci set network.mob1s1a1.reqprefix='56'
uci commit network
/etc/init.d/network restart

However, it should be noted, that the carrier must also support larger prefix delegation. To confirm that DHCPv6 is working, the IP address assigned to the mob1s1a1 interface should have a /56 or /64 prefix (not /128).
Hope this helps!

Best regards,

[kb0]

Terrific, thank you—that worked perfectly, the mob1s1a1 interface’s v6 IP now shows a /64 prefix instead of a /128.

What is the best configuration for passing these through to my downstream router—should I set the TRB500 as a DHCPv6 server delegating /64s, or put it in relay mode and pass the /56 through?

[Daumantas]

Hello,

If larger than /64 prefix is available on the WAN, then the best way to delegate them would be to make sure that Prefix delegation is enabled on the LAN interface. Prefix delegation length can be configured in the same menu:

Best regards,

[kb0]

That’s great. Thank you again.