--On Tuesday, April 28, 2020 10:16 PM -0500 Chris Adams linux@cmadams.net wrote:
I didn't get that you have a static assignment (presumably a business connection) - they may not do RAs on that (I don't at my ISP job). Business connections (or at least, connections with static assignments) tend to operate differently. For that, they should have given you a static v6 address and gateway, just like they did for v4.
I didn't think to ask when we were turning up the v4 and phones. I'm betting there's a setting in their gateway box but I'm waiting for them to give me the credentials to log into it.
So... there's one thing you could try (but probably won't work to a regular router interface) - see if there's a MAC-derived fe80::/64 link-local address on their end. Get the MAC of the gateway from the v4 ARP entry and expand it to a LL v6 address as fe80::xxxx:xxff:fexx:xxxx (split the MAC, put ff:fe in the middle). Try ping6 that address with %em2 appended (have to append the interface when using link-local addresses). I doubt it'll work, since I know Juniper (which IIRC AT&T likes) doesn't assign those (I can't remember for sure about Cisco and don't have a handy test target).
Good idea but alas it's not routing. I can ping6 their gateway but it won't route after I add it to the route table for the WAN interface. While pinging a remote server, in a second shell I can tcpdump icmp6 packets and I see the packets going out but no replies coming back.
And frankly, giving you a /56 is pretty crappy, since ARIN rules say to give every site a /48. I'd only do a /56 for a home connection prefix delegation. But, that's AT&T! :)
I'd just read about that when researching this. Maybe they decided that since we only have about a dozen people at our site, we won't have a lot of subnets. What do small offices DO with 256 public subnets, anyway? I suppose eventually we'll have an IoT subnet on every person.