In reply to a post by E300:

So I think personally the complexity comes in with the notations and how they are written, because the numbers are so big they are written in HEX and it's all a bit more complex.

I can remember and type my router's address, 192.168.1.1, easily. How complex would that be under IPv6?

In reply to a post by Woolwich:

How complex would that be under IPv6?

DNS is the answer.

You would type into the URL something more complicated, usually you need to surround an IPv6 address in square brackets, so examples might be:

https://[fe80::ac2:7aff:de6e:71ad]/ using the routers local address

or it would have a public IP address, something like

https://[2a02:280:77aa:11a4::1]/

or even something more complicated as those IPs have some zero's removed to shorten them.

But as suggested DNS would be the answer, after all we don't ever need to remember the IP address for websites. It's just a quirk of NAT and IPv4 that there are some addresses that are often used for such devices we know and remember.

In reply to a post by E300:

It's just a quirk of NAT and IPv4 that there are some addresses that are often used for such devices we know and remember.

and home networking. In corporates we either use DNS, or have to remember the real IP of the network infrastructure devices.

Yep to reach my main router I can still go by name as fritz.box or even just gw.

IPv6 tends to show up any historical gaps in having fully populated DNS in IPv4.

Discussions about the IPv6 nearly always have the same initial questions such as
1) use of Hex
2) size of addresses (and reasons)
3) why would everything need to be public

For (1) IPv4 would actually have been more regular for processing and comparing if originally represented in hex,
as all addresses could be stored as exactly 8 digits (with leading 0s).
Subnetting on 4-bit boundaries would look consistent, with sizes of 16 (lab), 256 (normal) or 4K (large) being naturally convenient.

Regarding (2) different sizes were discussed (such as 48*/64/80/96/128).
Realistically you would need a minimum 64-bit space to provide enough of a step in future proofing expansion. Even at 64-bit you would need to continue with variable length network prefix vs host portions of address to provide enough hierarchical networks and route aggregation.

(*) For comparison NAT masquerade is roughly equivalent to stretching IPv4 from 32-bit to a pseudo 40-42 bit address space based on parking 250-1000 hosts behind a single public IP; more than that risks not having a reliable pool of spare ports for new TCP/UDP connections.

The 128 bits are rarely evaluated in one go, more like 16-64 bits at a time for most usage.
The first 2 hex digits (8 bits) are now enough to classify the type of address (multicast, unicast, global, unique local, bogon ….) for a host or router to make some initial decisions on how to treat it.

One could describe the unicast network prefix/host split as scaling of (Class B)⁴.

The host portion being 64-bits was never about having that many hosts in a subnet, but supports enough bits to allow hosts to self-assign addresses on each interface that enables IPv6 (including both MAC address - based and randomised private options).

A key point is that IP addresses are assigned to a host's network interfaces (rather than the host) - this is also true of IPv4 btw but less obviously so when describing computers.
And that these addresses have scope (up to what boundary are they valid) so multiple addresses become normal by design rather than by exception.

Regarding (3) originally all IPv4 addresses would be global, but whether it was public or private would depend on whether the hosts were behind firewalls.
IPv6 restores that - an address being of globally routeable scope does not mean they are all public. If your gateway is a stateful firewall (the default convention for dual stack) the LAN behind it is private as regards inbound connections.

However ULAs (fdxx) also provide equivalent of private scope address space where you don't want the IP to be routeable outside networks you control and the flexibility to assign these alongside (or instead of) the global addresses.
They are commonly used to provide "well-known" addresses for LAN services which then do not depend on any network prefix from by the upstream provider (ISP) and so can be reliably persistent for your internal DNS.

Edited by prlzx (Sun 07-Feb-21 00:06:11)

Hurricane Electric have an IPv6 Certification project here: https://ipv6.he.net/certification/ which goes through all of the terms. However parts of it do need you to have IPv6 connectivity or the ability to host services on IPv6.

I've had an IPv6 tunnel through he.net for almost eight years. I don't find that it affects performance significantly. This was available long before my ISP supported IPv6. I keep the tunnel as the addresses are provider independent.

he.net allow you to request a /64 and a /48. If I recall correctly, the /48 is 1.2 septillion (2^80) addresses!

In reply to a post by ian72:

At the moment you can just turn off ipv6 and be unlikely to notice. It will be a while before you can turn off ipv4 without having issues - all of the noise about running out of ip address space and much of the industry still finds it easier to muddle through than to switch to ipv6.

A lot of business/government etc would look to spend their money on other things as ipv4 just isn't a big enough issue to force a change and until it gets really painful or hits profits or someone forces it then it just won't happen.

I agree. The death knell / pinch point / haemorrhage of public IPv4 addresses has been overplayed for years. To get meaningful mass scale adoption of v6 would require v4 to die completely.

Given measures like CGNAT (despite its end user disadvantages) have effectively given a fresh lease of life to v4, it is simply not about to crash in a heap any time soon. Despite the techical advantages of v6, the contemptible familiarity and sheer momentum of v4 will see it chug on I predict for many, many more years yet.

If zen switch it on for £0 then yes it is worth it. If its more than £0 then no. Websites work with IPV4 and then IPV6 added on top. True IPV6 for all services without IPV4 to your house are still a little bit away. Lots of services still rely on IPV4 to work