Re: [lwip-users] IPv6 Auto Config - Router advertisements, compatibility

They are some older year models, and I do not
see Router Advertisements coming from them. 

If there is no RA seen, then you should check your router first, e.g. your routers config about ipv6 nd ra setting, since some router switch off this function by default.

On 08/22/2019 05:25, Saad wrote:

Dear mailing list users,

I am successfully getting an address via IPv6 Auto Config on one router and
failing on others. I am developing an Ethernet product that will allow users
the option to get an IPv6 address dynamically from their router. We are
using LwIP and STM evaluation board. Thus far, I have successfully used
static IPv4 & IPv6 and dynamic IPv4.

I have successfully gotten an IPv6 address via auto config from my home
router, but have failed to do so on other routers in my office. Inspecting
Wireshark I see that my house router (Netgear, recently bought) sends out an
ICMPv6 Message #134 Router Advertisements about every 20 seconds. These RA
messages carry a prefix that prefaces the assigned IPv6 address on my LwIP
device. I see in my router settings that it is configured for "Auto Config"
and it displays the prefix. Inspecting the firmware in file nd6.c, I see
that RA messages are required for IPv6 Auto Config to work. It also seems
that the DHCPv6 stateless client requires an RA message to come in first
before working, based on the LwIP documentation site. *(When enabled,
requests are only issued after receipt of RA with the corresponding bits
set.)*

But the routers in my office are not working with IPv6 Auto Config and seem
to not even send RA messages. They are some older year models, and I do not
see Router Advertisements coming from them. My device does not get any IPv6
address via auto-config, but I am able to ping my link-local address and a
static IPv6 address on these routers.

I do not understand why these routers are failing Auto Config IPv6.

*Is it because they are older and lack support for IPv6?
*Are these routers filtering out the essential ICMPv6 messages?

I also saw on one router that a Router Solicitation is seemingly sent from
LwIP on boot and a Router Advertisement from the router is replied with, but
this RA does not seem to have a prefix for auto config in it.

Has anyone experienced this issue or have knowledge? I would appreciate any
help.

Thank you,
Saad Khan

DYMO



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