Understanding IPv6 routes in web UI

[brian7365]

Sometime in the past 60 days Verizon Fios started using IPv6 for my home service so now I'm trying to understand it. I know IPv6 is large enough that they may have given me a block of IPs to play with and I'm trying to understand if they did, how large it is, and if people have recommendations for what I should do with something a block size on a home network. If they didn't give me a block, should I ask for one and what size?

Additionally, I'd like to start hosting a few internet-reachable services and want to know if with these IPv6 addresses I can set up static IPs for those on my own or if I need to ask Verizon to do some config for me. I know that usually costs money for static IPv4 addresses but perhaps that is free with IPv6 now? Wondering what people recommend about that as well.

Here's what I'm seeing on my end and am trying to understand what it means for block size and home use:

[mikma]

The /56 prefix used as source on wan6 is the prefix Verizon has delegated to you.

The /64 prefix is the prefix that's assigned to the lan interface. On Ethernet interfaces the prefix size should always be 64. But you can use a larger IPv6 assignment length. In this case OpenWrt will support prefix delegation to down stream routers.

BTW when running ip addr show on the router it may seem like for example a /60 prefix is assigned to the lan interface. This is an oddity with OpenWrt, and in reality it's a /64 prefix that's on-link.

[lleachii]

@mikma

On Ethernet interfaces the prefix size should always be 64.

(Unless you have a downstream router.)

@lleachii

I even played around with getting IPv6 to a downstream ISP-provided router. I delegated a /62 to the interface/VLAN from wan6 and enabled DHCPv6, the device received a /63 PD and assigned a /64 each to its LAN and WAN, and made a Kernel route to the /63 via the other router's WAN link local IPv6 addresd - success!

@mikma

This is an oddity with OpenWrt, and in reality it's a /64 prefix that's on-link.

The route is made in Kernel, though.

[mikma]

@lleachii

The route is made in Kernel, though.

Really? Doesn't noprefixroute which is present on the IPv6 addresses mean the kernel doesn't add the route automatically?

[lleachii]

@mikma

Doesn't noprefixroute which is present on the IPv6 addresses mean the kernel doesn't add the route automatically?

Correct, in my use case, it doesn't make a /62.

It makes:

• a /64 for the OpenWrt interface
• a /63 via the link-local of the downstream router's WAN interface - for the PD it issued (this assigns a /64 to the downstream WAN and /64 to its LAN)

Therefore, in my scenario, there's one unused /64 after I subdivided and delegated /62.

@brian7365

Additionally, I'd like to start hosting a few internet-reachable services and want to know if with these IPv6 addresses I can set up static IPs for those on my own or if I need to ask Verizon to do some config for me. I know that usually costs money for static IPv4 addresses but perhaps that is free with IPv6 now?

The IPv6 addresses are not static as provided...in fact I've observed they sometimes change on renew (i.e. IPv6 goes out on my downstream until it gets a PD renewal a few seconds/minutes later) - which is about 2 hours from my observation. You will need an IPv6-enabled DDNS service to assign an AAAA DNS record to an IPv6 address.