3 ms·

> (and, in some ways, is actually much easier to understand and remember) Can you explain this?

digitalsushi 14y ago
One can chose addresses that maximize compressible sequences of zeros. If I were allocated a subnet of 2002:/, I could make my computer's address 2002::2 and my router 2002::1. Realistically the first 64 bits are going to be very ugly, so I disagree that a v6 will ever be much easier to remember than a v4 address. Especially with the 0 compression being back-ported to v4 stacks, running on the 10. network - You can ping 10.1 as 10.0.0.1 on many stacks now.
duskwuff 14y ago
My guess: Since any given organization's IPv6 allocation is so large, there's no need to densely pack the addresses that you're using, so it's much easier to stuff human-readable information into the address. For instance, one of the segments of $work's IPv6 addresses is an ID indicating what facility the machine is located at.
ghshephard 14y ago
First, my perspective is that IPv6, to some degree, abandons 15+ years of VLSM (Variable Length Subnet Masks) - so, at a glance, without referring to a subnet mask, you can identify what position of the address is a network, and which portion is the host element. There is a 64 bit network and 64 bit host field. Second, The network portion for most enterprises is going to be a 48 bit super net (which network admins will memorize within a few days of working within a particularly company) followed by a 16 bit network portion. So, in the above example, the 48 bit super net is 2001:1868:209 and the network portion is FFFD. So - now, when I see an IPv6 address, my eye automatically scans the network portion, much, much more quickly than I did in the IPv4 world, where we had 30 or 40 IPv4 networks, many of them with their own strange /30, /28/ /26 /25, etc.. net masks. I've been doing this for 16 years, and I still can't transparently do the math in my head for all variants of IPv4 - and even 2-3 seconds of translating /27 into 5 bits into 32 addresses into boundaries of 0,32,64,96,128,etc... can break your concentration. That problem no longer exists with IPv6. It's a 48 bit super net + 16 bit network for most enterprises. Now, for those who aren't using the privacy elements, you also have advantage of embedding the MAC address in the address, so, for those of us who are OUI geeks, we can also identify the equipment in the address so (it's the first 24 bits of the host portion, with a bit of bit twiddling the in 7bit Local/Global spot) - and, we can also see whether proper EUI-64 expansion has taken place (in the above example, it hasn't - the proper EUI-64 expansion would be 0213:50FF:FE12:3456) So - at a glance, I see the network, sub network, and hardware, skim over the FF:FE filler, and, the actual address - 12:3456 is simple to remember. Finally - if you have a lot of hosts you are trying to put on a single network, you don't have to play games. We routinely put 25,000 devices on a single routed link, and we aren't concerned about rolling out 2,000 of those 25K device routed links for a particular instance. And we can (and have) rolled out a hundred instances of such configurations, with no overlap in addressing between any of them. Try that without gymnastics in the IPv4 world. In IPv6 it just follows the simple rules of 48 bit supernet + 16 bit network + 64 bit host field. It takes a couple years (or at least it took me a couple years) - but once the brain's rewired - the additional structure is in _some way_, easier to understand and remember -but obviously this is all within a particular hardware and enterprise context. Clearly a Random 32 Bit IPv4 address is easier to memorize than a random 128 Bit IPv6 address.

One can chose addresses that maximize compressible sequences of zeros. If I were allocated a subnet of 2002:/, I could make my computer's address 2002::2 and my router 2002::1. Realistically the first 64 bits are going to be very ugly, so I disagree that a v6 will ever be much easier to remember than a v4 address. Especially with the 0 compression being back-ported to v4 stacks, running on the 10. network - You can ping 10.1 as 10.0.0.1 on many stacks now.

duskwuff 14y ago

My guess: Since any given organization's IPv6 allocation is so large, there's no need to densely pack the addresses that you're using, so it's much easier to stuff human-readable information into the address. For instance, one of the segments of $work's IPv6 addresses is an ID indicating what facility the machine is located at.

ghshephard 14y ago

First, my perspective is that IPv6, to some degree, abandons 15+ years of VLSM (Variable Length Subnet Masks) - so, at a glance, without referring to a subnet mask, you can identify what position of the address is a network, and which portion is the host element. There is a 64 bit network and 64 bit host field. Second, The network portion for most enterprises is going to be a 48 bit super net (which network admins will memorize within a few days of working within a particularly company) followed by a 16 bit network portion. So, in the above example, the 48 bit super net is 2001:1868:209 and the network portion is FFFD. So - now, when I see an IPv6 address, my eye automatically scans the network portion, much, much more quickly than I did in the IPv4 world, where we had 30 or 40 IPv4 networks, many of them with their own strange /30, /28/ /26 /25, etc.. net masks. I've been doing this for 16 years, and I still can't transparently do the math in my head for all variants of IPv4 - and even 2-3 seconds of translating /27 into 5 bits into 32 addresses into boundaries of 0,32,64,96,128,etc... can break your concentration. That problem no longer exists with IPv6. It's a 48 bit super net + 16 bit network for most enterprises. Now, for those who aren't using the privacy elements, you also have advantage of embedding the MAC address in the address, so, for those of us who are OUI geeks, we can also identify the equipment in the address so (it's the first 24 bits of the host portion, with a bit of bit twiddling the in 7bit Local/Global spot) - and, we can also see whether proper EUI-64 expansion has taken place (in the above example, it hasn't - the proper EUI-64 expansion would be 0213:50FF:FE12:3456) So - at a glance, I see the network, sub network, and hardware, skim over the FF:FE filler, and, the actual address - 12:3456 is simple to remember. Finally - if you have a lot of hosts you are trying to put on a single network, you don't have to play games. We routinely put 25,000 devices on a single routed link, and we aren't concerned about rolling out 2,000 of those 25K device routed links for a particular instance. And we can (and have) rolled out a hundred instances of such configurations, with no overlap in addressing between any of them. Try that without gymnastics in the IPv4 world. In IPv6 it just follows the simple rules of 48 bit supernet + 16 bit network + 64 bit host field. It takes a couple years (or at least it took me a couple years) - but once the brain's rewired - the additional structure is in _some way_, easier to understand and remember -but obviously this is all within a particular hardware and enterprise context. Clearly a Random 32 Bit IPv4 address is easier to memorize than a random 128 Bit IPv6 address.