On 04/10/17 06:39, Ed Greshko wrote:
On 04/10/17 05:33, Stephen Morris wrote:
> Thanks Rick, am I correct in understanding that you are saying that
> even though I have IPv6 set to link-local, that IPv6 is still being
> attempted across the internet gateway, and in my case because my ISP
> doesn't support IPv6, I am assuming those packets would be rejected
> and hence the system would fall back to IPv4, or is it the case that
> IPv6 is tried for every transmission, which would then make internet
> access horribly inefficient?
No. The link-local addresses are not route-able. They cannot traverse
routers. Any DNS response with a IPv6 address will not be utilized.
So, you wouldn't get any IPv6 traffic attempting to go out the WAN path.
To further illustrate....
With full IPv6 available this is the routing table.
Kernel IPv6 routing table
Destination Next Hop Flag Met Ref
Use If
2001:470:d:6bd::/64 :: U 100 0
0 enp0s3
fe80::ae22:bff:fed1:5d70/128 :: U 100 0
0 enp0s3
fe80::/64 :: U 256 0
1 enp0s3
::/0 fe80::ae22:bff:fed1:5d70 UG 100 0
0 enp0s3
::/0 :: !n -1 1
14269 lo
::1/128 :: Un 0 2
17 lo
2001:470:d:6bd:8800:f914:12ee:a343/128 :: Un
0 1 9 lo
fe80::5a1c:5ee4:bc16:2b7d/128 :: Un 0 2
10 lo
ff00::/8 :: U 256 1
22 enp0s3
::/0 :: !n -1 1
14269 lo
Notice the ::/0 with a nexthop address? That is the default route for
IPv6 traffic.
With link-local...
Kernel IPv6 routing table
Destination Next Hop Flag Met Ref
Use If
fe80::/64 :: U 256 0
4 enp0s3
::/0 :: !n -1 1
14226 lo
::1/128 :: Un 0 2
17 lo
fe80::5a1c:5ee4:bc16:2b7d/128 :: Un 0 1
12 lo
ff00::/8 :: U 256 1
22 enp0s3
::/0 :: !n -1 1
14226 lo
No default route....
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