1

The router for my local network advertises two IPv6 prefixes (one local, fdXX:: prefix, and one delegated from my ISP). I've confirmed that they're both being advertised by inspecting the router advertisements with Wireshark, thus:

router advertisement contents

However, Windows hosts on the network only seem to pick up one of the prefixes (and consistently the fdXX:: one) to use:

Ethernet adapter Ethernet:

   Connection-specific DNS Suffix  . : arkane-systems.lan
   IPv6 Address. . . . . . . . . . . : fdc9:b01a:9d26:0:fd4c:9cca:2051:c663
   Link-local IPv6 Address . . . . . : fe80::21cd:60d4:2e62:cc29%14
   IPv4 Address. . . . . . . . . . . : 172.16.1.2
   Subnet Mask . . . . . . . . . . . : 255.255.0.0
   Default Gateway . . . . . . . . . : fe80::217:94ff:fef2:c3f%14
                                       172.16.0.254

Why is this happening, and is there any way I can get the hosts to pick up on both interfaces?

Cerebrate
  • 174

1 Answers1

2

My first question I would ask is why you are announcing 2 prefixes. I am not sure how Windows built its stack, but I would expect it is looking for one route.

The fdc9: prefix should not be used for global (internet) routing. However, given the lifetimes, it appears to be the preferable network in terms of lifetime. Also it is closer to the desired /64 for a local routing block. Is there any reason for having a local identifier when the global identifier would work as well?

The 2600: prefix is being advertised with the full /48 supposedly supplied by your ISP. Normally this would be broken down into /64 sub-nets with each router being assigned a sub-net. This would be good for 65536 routers in your organization. Try advertising a /64 subnet and see what happens.

BillThor
  • 28,293
  • 3
  • 39
  • 70