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Forum Discussion
Daisy Chain Orbi Routers w/ IPv6?
Wondering if anyone has successfully Daisy Chained two Orbi routers and had working IPv6 on the second router.
I understand that having one router 'behind' another router is not a recommended practice. As an experiment, I once connected three routers A-B-C and demonstrated that IPv4 works in that environment. Port forwarding is a bit of a hassle, since the port has to be forwarded through router A to router B, then through router B to router C, and finally through router C to the target device. But.... it CAN be done.
My RBR50 connected to Spectrum has a working IPv6 network. Devices can connect to other devices using IPv6. IPv6 Ping works. Devices have both local and public IPv6 addresses.
My goal is to connect an RBR750 to my existing RBR50 and have a working IPv6 network on the RBR750. However, when I enable IPv6 on the RBR750, it gets an IPv6 address on the WAN port from the RBR50, but on the LAN side there is no IPv6. Google search (A.I.) seems to indicate that it is possible to pass IPv6 through multiple routers and mumbles on about "Prefix Delegation" and IPv6 LAN advertisement, etc.
The question is CAN this be done? If so, HOW?
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While I looked briefly at getting double-routing ipv6 (Verizon-> Orbi 870), I dropped looking into it as other priorities came along. IPv6 is currently disabled (and re-enabling and experimenting again would require several reboots of the router, which I don't want to do right now).
There are a couple basics:
Every device using IPv6 natively over the internet has a globally unique IPv6 address. There is no NAT and no need for port forwarding.
There is a large "link local" (not internet routable) address block. While these addresses can be used for local network data flows, the main purposes are more administrative. For instance allowing devices to discover other devices on the local network, get gateway information from their routers, etc. So these are used differently than private IPv4 addresses. These link-local addresses are always self-assigned.
Also there is a special address block that is used to represent any ipv4 address as an ipv6 address.
Your ISP is giving you an address block of IPv6 addresses, not just a single IPv6 address. You do need to know how large that block is. Verizon gives me a /56 block (which is usually the smallest block assigned to a single customer site, though some might give out a /60 block). This is a huge address block - 2**72 globally unique ipv6 addresses.
Normal practice would be to assign a /64 block (2**64 addresses) to the RBS750 clients. (You don't want to go smaller than that, since processes like SLAAC break if you do). That assignment is what the "Prefix Delegation" is about. This is similar to the subnet concept in IPv4 (but again with no NAT). The "Prefix" is the beginning section of the IPv6 address block (the part that is the same for all IPv6 addresses in the block).
So a /64 network has a 64 bit network prefix, followed by a 64 bit host section. A /56 network has a 56 bit prefix, followed by 8 additional bits that you use to allocate up to 256 /64 subnets. Then a 64 bit host section for each of those subnets. Similarly, a /60 address block has a 60 bit prefix, followed by an additional 4 bits that you use to allocate up to 16 /64 subnets.
The Verizon router by default allocates the first /64 block for its local devices (subnet 0). It has a field where I enter the subnet ID for its address distribution, so I can change that. I can also set up the router explicity to use DHCPv6-PD, or to use SLAAC.
Not sure how to set up the Orbi to automatically take the second subnet for its address distribution - I didn't get that far in my investigation. In my brief look, I found the Orbi set up to be quite confusing - the settings and terminology didn't map well onto my IPv6 terminology. Although I'm not a huge fan of the Verizon web interface, its IPv6 settings are much clearer.
Thanks for taking the time to respond. Will look to see what Spectrum publishes about IPv6. When I look at the router IPv6 page, there does not seem to be much useful information.
I can see the IPv6 of my router (/128 prefix), and the IPv6 assigned to my PC, the router LAN interface, and some other devices on the network.
2605:e000:3fc0:3e:d2:44a9:3c1a:e199/128 - router WAN
2603:8000:403:bd7c:a204:60ff:fe1c:239/64 - router LAN
2603:8000:403:bd7c:ff9d:7e3f:f1c1:1dd9 - PC
2603:8000:403:bd7c:6ecd:d6ff:fe02:3ea9 - WAN interface on the RBR750
Somehow the PC seems to generate 'temporary' IPv6 addresses:
Temporary IPv6 Address. . . . . . : 2603:8000:403:bd7c:4d42:6333:cb95:f3(Deprecated)
Temporary IPv6 Address. . . . . . : 2603:8000:403:bd7c:9515:68f4:4a98:651e(Preferred)
Temporary IPv6 Address. . . . . . : 2603:8000:403:bd7c:bc2f:48bb:cc14:432(Deprecated)
Temporary IPv6 Address. . . . . . : 2603:8000:403:bd7c:ed98:68ae:7d87:ed61(Deprecated)
Temporary IPv6 Address. . . . . . : 2603:8000:403:bd7c:f07d:55d7:c8b5:ed6a(Deprecated)
Temporary IPv6 Address. . . . . . : 2603:8000:403:bd7c:f42a:e0d3:73e1:1571(Deprecated)
Have you tried setting the RBR750 ipv6 setting to pass-through mode?
That should make it work like an ipv6 switch (leaving the routing up to the RBR50).
Thanks for responding. Unless I misunderstand, putting the 750 in "pass-through" mode appears to be equivalent to setting the 750 to Access Point (AP) mode rather than router mode.
AP mode is certainly what would be recommended, but my goal is to figure out how to get the 750 to support IPv6 in router mode.
(Actually, I believe that I did select "pass-through" mode and it seemed to have no positive effect.)
grrrr. This all started because of a post on the Forum about firmware updates having 'broken' IPv6 on the Orbi 850 and I wanted to be able to contribute "something" to the discussion.
I considered designating the RBR750 as the DMZ server, thinking perhaps it would get IPv6 from Spectrum (in addition to the primary RBR50 router).
.......... this is SO frustrating!!!
StephenB is perfectly right:
The IPv6 on your LAN is /64 - which can not be segemented (or subnetted) any further. Doing so would break IPv6 core features like SLAAC which strictly requires 64 bit for the interface ID. Similar, NDP (the Neigbor Discovery Protocol) rely heavily on the 64 bit boundary.
The smalles practical IPv6 subnet would be /56 - which would be the RIR and industry standard recommendation for reisdential customer sites. That would allow 256 distinct subnets. But no ISP does really care about...
