How is a home/private network's ipv6 network number assigned to Cable Modems?

For typical IPv4 home network deployments, the private network is made up of private IP addresses (usually 192.168.0.0/24). All devices share the router's public (Internet-routable) IP address assign...

vkdelta

NETGEAR Employee Retired

Feb 29, 2020

There is no NAT in IPv6. It was designed to avoid that in first place.

Basically IPv6 in cable has three parts.

you Cable Gateway (2-in-1 combo box) has 3 key items:

1. CM IPv6 address --> Single IPv6 address to manage the Cable Modem via SNMP. You will most likely not able to see this.

2. WAN IPv6 address -> Single IPv6 address pointing to your device's WAN port. This is same stack as your WAN Public IPv4

3. Delegated IPv6 prefix -> your ISP is supposed to send a whole 64 bit (or lower sizee) delegated prefix for your home devices. they get divided and shared between all the devices.This prefix is sent over by ISP and not dictated by the device.

all the traffic from Delegated Prefix subnet is routed via WAN IPv6 address (but NOT NAT'ed)

when your device is talking to a website, it is actually usings its own IPv6 address.

here is old comcast presentation from John B

https://archive.nanog.org/meetings/nanog46/presentations/Tuesday/Brzozowski_introDHCP_N46.pdf

additionally look at Ipv6 section below

https://archive.nanog.org/meetings/nanog46/presentations/Sunday/Byju_Intro_DOCSIS_N46.pdf

vkdelta

NETGEAR Employee Retired

Feb 29, 2020

some videos ifyou are interested

https://www.youtube.com/watch?v=d_K6NGBseoQ&feature=youtu.be

https://www.youtube.com/watch?v=yfFg51lmF34&feature=youtu.be