Comment by gerdesj | Hacker News Reader

Comment by gerdesj | Hacker News Reader

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I use copy and paste for both IPv4 and IPv6 addresses.

I understand where you are coming from by adding a few more bytes to the address scheme but one of the things IPv6 was designed for was massive address aggregation which means really short routing tables. Your 192.192.168.168.0.0 (say) scheme does not go far enough. Also, your scheme needs to be efficient in the world of bits and bytes and I don't think it is. Your scheme would probably need to be 64 bit to start with and not 48 bit because silicon, etc doesn't work like that.

However that simple routing scheme was blown out of the water by private addressing - ie get your own ISP independent address range. When you change ISP you end up with another prefix and hence all your addresses change. All addresses. So you buy your own range (about £3000 set up and £3000 per year from memory. You also need an ISP(s) to route it and if more than one then a BGP peering arrangement.

Another wrong in the name of IPv6: 64 bit IPv6 prefixes from an ISP means you can only have one subnet. No way to put your dodgy IoT stuff on its own VLAN.

The recommendation is to assign a /56 to end users from an ISP. That would give you plenty of subnets to work with.

/56 == 256 /64s Each /64 == 18,446,744,073,709,551,616 addresses

Sadly, plenty of ISPs use DS-Lite with a single /64 issued.

(I'm looking at you UPC/Virgin Media/Liberty Global)

Vodafone cable in germany does the same..

I have a pretty good ISP - I get a /56 but the original idea was /48 for everyone. I only have 256 subnets available. With /48 I would have say 256 x 256 subnets which would be ideal for my family. With /56 I have very little elbow room.

Each subnet (/64) is 18,446,744,073,709,551,616 addresses - which is nice.

Sorry I'm not sure i understand:

> Another wrong in the name of IPv6: 64 bit IPv6 prefixes from an ISP means you can only have one subnet. No way to put your dodgy IoT stuff on its own VLAN.

Can't your router handle carving up a subnet just fine?

A lot of self-assigned IPv6 networks just tack on the device's 64-bit MAC address on to the end of some 64-bit network prefix. So if you're going with self-assignment of IPv6 addresses then you will have difficulty if your assigned prefix is already 64-bits, since you can't really use any of the 64-bit suffix bits for your own network.

The mechanism is called StateLess Address Auto-Configuration (SLAAC) [0]. It removes the need for DHCP, and the determinism is very convenient. There are of course privacy downsides for deterministic addresses that are globally routable, and that's where SLAAC privacy extensions come in [1].

[0] https://en.wikipedia.org/wiki/IPv6#Stateless_address_autocon...

[1] https://en.wikipedia.org/wiki/IPv6#SLAAC_privacy_extensions

More precisely, disabling the autonomous addressing flag in the router advertisement packet allows you to completely control the addresses which will then only be handled by DHCPv6, which allows you to slice a /64. But that means no v6 temporary addresses for anonymisation, which might be exactly what you want in a managed network/corporate scenario which requires liability tracing.

What are you using at layer 2 that has 64-bit MAC addresses?

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