Posts by JKnott 27 publicly visible posts • joined 10 Feb 2024
"Yes but you only have 8 bits of subnetting so most of that address space isn't useful. In another brilliant move by the IPv6 team, the entire last /64 of the address space is not routable. The reason they did this is so that the MAC address of every device could be in that part but smarter people quickly realized that was a really, really stupid idea. Like so many other things in IPv6 that are still being reworked, broken, respecified, and redisgned. Not to mention that it's completely incompatible with IPv4 despite IPv4 having a "version" field. As these core original design flaws pile up it turns out IPv6 is just a really bad design that nobody wants. Everybody wants more address space, IPv6 is not the way."
That 64 bits represents the standard subnet size, which everyone gets. You generally get several of them for routing, etc.. For example, I have a /56 prefix from my ISP, which gives me 256 /64 networks. I can route those all I want. Also, you don't have to include your MAC address if you don't want to. Aside from the address space, there were a lot of things that were changed from IPv4 to improve things like performance. Broadcasts are gone, in favour of multicasts. This allows for more focused use. ARP is gone, but then it wasn't originally part of TCP/IP. It was there and used, instead of coming up with something new. With IPv6, that function is now part of ICMP6.
BTW, IPv6 address space is so huge, every person on earth could have over 4000 /48s.
"> There are not even enough IPv4 addresses for all the mobile devices.
Does that really matter? We have IPv6 and ways of using IPv4 over the IPv6 carrier service."
Yes. NAT, etc. are barriers to a seamless service, where one phone can talk directly to any other.
"> NAT breaks things.
Depends on what you mean, the original RFC for NAT and the subsequent one for NAPT contain guidance for FTP and ICMP. Okay the solution isn’t elegant etc., but a workable solution was presented. I suspect many of the problems people experienced were more to do with poor implementations of NAT & NAPT (and thus the implementation of the FTP packet header rewriter) although the level of detail in the relevant RFCs does leave much to be desired…"
I've been around long enough to remember command line FTP clients. That was the first thing I remember being broken by NAT. These days, STUN servers are needed for VoIP and some games to get around NAT. Your solution seems to be hack on hack to get around fixing the problem properly.
"NAT did more than this. Remember prior to the ready availability of Internet access, many office networks ran TCP/IP, mostly using the private address ranges (specifically 192.168..). NAT permitted these networks to be readily connected to an ISPs service and gain access to the public Internet. Subsequently, it has made it easy switch ISPs."
Back in the late 90s, I worked for IBM Canada. At that time, I had 5 public IPv4 addresses, 1 for my own computer and 4 for testing in my work, and NAT was nowhere to be seen. I remember the days before NAT and how things were supposed to work. NAT was simply a means to get around the address shortage and caused other problems in the process.
You're missing two important points. There are not even enough IPv4 addresses for all the mobile devices. Cell phones have moved to VoIP (VoLTE, VoNR) and they each need a public address, just for voice and they still need one for data. Also, the rest of the phone system has moved or is moving to VoIP.
Also, NAT breaks things. The first thing I was aware of that it broke was FTP, back in the days when we used command line clients. Lately, it's been things like VoIP and some games. The hack for that is STUN servers, so we have a hack on a hack, just to get around the address shortage.
Of course that 2³² addresses is not entirely usable due to various reserved blocks and addresses lost due to block sizes always being powers of 2.
"Now put your phone in hotspot mode and seen how many devices can connect through it?"
I don't think you'll find many networks where there aren't practical limitations on how many devices you can connect, long before you reach the numerical limit. For example, MAC addresses are 48 bits. How many devices can you practically connect?
I normally connect only one device to my phone, so I can't say what the max is.
"So, comments seem to agree that IP6 has far more addresses than anyone could ever need"
First off, if you want simple addresses, there's nothing to stop you from assigning them. Also, you can always use DNS so that you can access devices by host name. You should be doing that anyway.
We're long past the days when every byte counts and we also no longer have to worry about having sufficient addresses. Sticking with IPv4 means sticking with NAT and that means breaking things. It also means some people will not have a reachable address for use with VPNs etc., because they're stuck behind carrier grade NAT (CGNAT). IPv5 was an experimental streaming protocol that never went anywhere, but parts of it are incorporated into IPv6.
One thing that's driven IPv6 is mobile devices. There simply aren't enough IPv4 addresses to support them. With cell phones, 2 addresses are needed, 1 each for voice calls and for data. For this reason, VoLTE uses IPv6. Some telecom companies have found there aren't enough RFC 1918 addresses to operating their networks, without splitting them into zones. For them, remaining with IPv4 just creates one big mess, where one part of the network is not reachable from another part.
There are a lot of reasons moving to IPv6 is a good idea and none that sticking with IPv4 is.
"Sure, IPv6 supports multiple addresses on an interface. Which source IP address does your application use and how does it find out?"
I don't know all the details, but RFC 6724 covers part of that. Also, as I mentioned, routers can have priority, so that would help choose the best source address.
"Do they really have IPv6 ONLY devices? Can you point to any, i.e. link to specs that show they do not support IPv4 at all?"
Android phones use 464XLAT to access IPv4 only sites over the IPv6 only cell network. My current and previous cell phones worked that way with IPv4. They get a public IPv6 address and /64 prefix. For IPv4, the address is 192.0.0.4, which is used with 464XLAT.
"Now try and connect to your phone from the Internet using IPv6, that will confirm whether it is using a public or (more likely) private IPv6 address and thus your carrier is using IPv6 NAT…"
While I don't know about my carrier, some block incoming connections. However, I can look in my phone's info and see a real IPv6 address. No need for NAT on IPv6.
"> Do they really have IPv6 ONLY devices?
Suspect not, although with the widespread adoption of 4G I can see there being IPv6 only networks, so a host’s IPv4 interface isn’t publicly accessible."
That's the case with my cell phone. It's IPv6 only and uses 464XLAT when needed to access IPv4 only sites.
"What is probably more problematic is the hiding of my network. If I use my EE 4G router (ie. an IPv6 device), I am limited by EE as to the number of devices on my LAN who can talk to the internet. Swap the EE router for my own router and use NAT, EE only sees one device …"
That's not much of a network. I get a /56 prefix from my ISP, which is 2⁷² addresses. Even my cell phone gets a /64 for tethered devices. No need for NAT, with 18.4 billion, billion addresses.
"Multi-homing was never really intended for IPv6"
????
It most certainly is. IPv6 supports multiple addresses on an interface. You can also have multiple routers, with a priority assigned, so that if one dies there's another ready to go.
As for broadcasts, the IPv6 equivalent is the all hosts multicast.
"The IPv6 address space might in theory be very large, but given the issues around IETF’s use of the word “reserved”, it may be artificially limited:"
In that 1/8th the address space there are enough addresses to give every single person on earth over 4000 /48 prefixes. Each /48 contains 2⁸⁰ addresses. Yep, really limited!
"Depends what you mean by performance hit."
Broadcasts were around long before multicasts. As a result, they were often used when a multicast, to a smaller group, would have been more appropriate. With a broadcast, the device receiving it has to stop what it's doing, process the broadcast to see if it's interested and then resume. With multicasts, the device only listens to what it wants and unwanted multicasts are discarded by the NIC.
"Sometimes you need the megaphone"
The IPv6 equivalent is the all hosts multicast. That will be received by all devices on the network. It's typically used for router advertisements etc.. By using multicasts, instead of broadcasts, you can focus on the intended audience only and not bother everyone else.
"It's a perfectly valid point, and the truth (albeit an uncomfortable one for some) seems sound. Despite the obvious advantages of IPv6*, the reality is that only a tiny, tiny minority of sites or hosts will be IPv6 only - for 'reasons', mainly because, generally you would like others to connect to it, and without an IPv4, that's really not going to happen."
There's lot of IPv6 only in Asia. You know, little countries such as China and India that have so few IPv4 addresses to serve huge populations. Way back in the dark ages, when the Internet was just starting up, it was largely limited to the U.S. and that's where most of the addresses were allocated, leaving very few for Asia, Africa, etc..
Instead of all this nonsense about extending IPv4, why not just get off the pot and move to IPv6. It's been around for years, I've been using it since May 2010, and is the future. There are a lot of benefits to it, beyond just the unbelievably huge address space. I have a /56 prefix from my ISP, which provides 2⁷² addresses! It was also tidied up a bit from IPv4 to improve certain aspect and improve performance.
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