IPv6 Routing using Arris TG2472 modem (Cox Wireless modem) & Juniper SRX firewall

 Hi All,

I was about to ask if anyone had this working, but figured it out and thought I'd share as this would be gold information for a few with the need.

I have a Juniper SRX240 setup behind the Arris TG2472 modem. The modem can do IPv6 and will pull an address using SLAAC.

Any, the Arris modem is using a link-local as the gateway. It says the link-local is FE80::226:99FF:FE89:EBD9.

On my juniper, I entered the command, 'set routing-options rib inet6.0 static route 0::/0 qualified-next-hop fe80::226:99ff:fe89:ebd9 interface ge-0/0/0.0'. This is the command required to enter a link-local as a next-hop (more or less gateway) for the firewall.

I tried to ping google v6 dns (2001:4860:4860::8888) and it didn’t work. I had a client plugged into the Arris modem as well as it was successful, so I checked the IPv6 neighbors on the windows client and didn’t see fe80::226:99ff:fe89:ebd9, but I did see fe80::3e7a:8aff:fefb:3609 (check output below) and more specifically, it is also a router. I changed the Juniper cmd to 'set routing-options rib inet6.0 static route 0::/0 qualified-next-hop fe80::3e7a:8aff:fefb:3609 interface ge-0/0/0.0' and viola….IPv6 Magic! So, I don’t even see the link-local that the Arris modem says it sees, but whatever…likely a bug.  This is now working.

BTW, you get a /60, so I am testing using routed /64’s behind each other to see if that works. It should, but you never can tell with cheaper gear.

Happy routing!

C:\WINDOWS\system32>netsh interface ipv6 show neighbors

Interface 6: External                (Note, this is what I named my NIC, yours will likely be Local Area Connection 1).

Internet Address Physical Address Type
-------------------------------------------- ----------------- -----------
2600:8801:9600:a60::27 64-87-88-4f-53-00 Reachable (Router)
2600:8801:9600:a60:dc0b:16ff:7396:46a3 30-f9-ed-b9-d5-ec Stale
fe80::2021:1669:3f57:ffe4 00-00-00-00-00-00 Unreachable
fe80::3987:e30a:9749:495f 00-00-00-00-00-00 Unreachable
fe80::3e7a:8aff:fefb:3609 3c-7a-8a-fb-36-09 Reachable (Router)
fe80::42b4:f003:e8f9:7f01 Unreachable Unreachable
fe80::59e4:f17b:7bc0:d5b7 08-3e-8e-c1-a9-1d Stale
fe80::6c9b:c68e:caa:d83f 30-f9-ed-b9-d5-ec Stale
fe80::d01d:4ba:5d4a:6273 00-00-00-00-00-00 Unreachable