4 ms·

IPv6 support existed in even Windows XP, if not older. Things without IPv6 support are already obsolete.

jeroenhd 3y ago
A bunch of IoT hardware and other microcontroller-based hardware has IPv6 support, but that support is often disabled to save a couple of kilobytes of flash memory. You can buy all kinds of hardware today that lacks IPv6 support. Of course, if that hardware needs to access IPv6 services, they might as well disable IPv4+ICMP+DHCPv4 support and enable the IPv6 size in firmware, and probably get similar savings. To be honest, I'm not sure why companies still ship ESP32-like hardware with that little storage given how cheap flash storage is, but these optimisations are more common than one might think or hope.
- gmuslera 3y ago
  That is basically planned obsolescence. The world (except a few regions) is essentially out of IPv4 addresses.
  - jeroenhd 3y ago
    There are plenty of IPv4 addresses for server use, and IPv4 in client networks is easily accomplished using whatever form of NAT you prefer. DNS64+NAT64 will work fine for IoT crap (not like your thermostat is validating DNSSEC), and a whole bunch of ISPs rely on DS-Lite+CGNAT to allow IPv4 connectivity over their essentially IPv6-only backbone already. Publicly reachable IPv4 on the consumer side is dying rapidly, but IPv4 LANs and servers can still work exactly because of the versatility IPv6 allows.
  - msm_ 3y ago
    As it has been since 2011, and yet here we are.
- loup-vaillant 3y ago
  > A bunch of IoT hardware and other microcontroller-based hardware has IPv6 support, but that support is often disabled to save a couple of kilobytes of flash memory. Wait a minute, kilobytes? That much? It’s not like one needs to duplicate the entire IP layer, it seems to me the only changing parts are parsing & generating the packets.
  - jeroenhd 3y ago
    For IPv6 you need to implement NDP, RA, and a bunch of changes to the DHCP server. You also need to start paying attention to ICMP. The documentation for ESP-IDF (https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/lwip.html?highlight=CONFIG_LWIP_IPV6 https://docs.espressif.com/projects/esp-idf/en/latest/esp32/...) says: > Disabling CONFIG_LWIP_IPV6 can save about 39 KB for firmware size and 2 KB RAM when the system is powered up and 7 KB RAM when the TCP/IP stack is running. If there is no requirement for supporting IPV6, it can be disabled to save flash and RAM footprint. > Disabling CONFIG_LWIP_IPV4 can save about 26 KB of firmware size and 600 B RAM on power up and 6 KB RAM when the TCP/IP stack is running. If the local network supports IPv6-only configuration, IPv4 can be disabled to save flash and RAM footprint. IPv6 takes up more ROM than IPv4, and as far as I know ESP-IDF doesn't actually fully support IPv6 either. At this point we're talking microcents of storage, but unfortunately the 13KB of size difference can make the difference between "the code fits" and "we need to spend a dollar more per unit".
    - loup-vaillant 3y ago
      My it really is kilobytes. Okay I guess my next project will be a TCP-IP stack on an 32-bit RISC-V micro-controller, we’ll see how much code this actually requires. My understanding of IP may be off, but I still feel those numbers are about an order of magnitude bigger than they actually need to be. I mean, I can fit an entire cryptographic library¹ in 65Kib of RV32IC object code, and it’s not even particularly optimised for this use case. There’s no way the overhead of supporting IPv6 has to be that big. [1]: https://monocypher.org https://monocypher.org
      - 3y ago

A bunch of IoT hardware and other microcontroller-based hardware has IPv6 support, but that support is often disabled to save a couple of kilobytes of flash memory. You can buy all kinds of hardware today that lacks IPv6 support. Of course, if that hardware needs to access IPv6 services, they might as well disable IPv4+ICMP+DHCPv4 support and enable the IPv6 size in firmware, and probably get similar savings. To be honest, I'm not sure why companies still ship ESP32-like hardware with that little storage given how cheap flash storage is, but these optimisations are more common than one might think or hope.

gmuslera 3y ago
That is basically planned obsolescence. The world (except a few regions) is essentially out of IPv4 addresses.
- jeroenhd 3y ago
  There are plenty of IPv4 addresses for server use, and IPv4 in client networks is easily accomplished using whatever form of NAT you prefer. DNS64+NAT64 will work fine for IoT crap (not like your thermostat is validating DNSSEC), and a whole bunch of ISPs rely on DS-Lite+CGNAT to allow IPv4 connectivity over their essentially IPv6-only backbone already. Publicly reachable IPv4 on the consumer side is dying rapidly, but IPv4 LANs and servers can still work exactly because of the versatility IPv6 allows.
- msm_ 3y ago
  As it has been since 2011, and yet here we are.
loup-vaillant 3y ago
> A bunch of IoT hardware and other microcontroller-based hardware has IPv6 support, but that support is often disabled to save a couple of kilobytes of flash memory. Wait a minute, kilobytes? That much? It’s not like one needs to duplicate the entire IP layer, it seems to me the only changing parts are parsing & generating the packets.
- jeroenhd 3y ago
  For IPv6 you need to implement NDP, RA, and a bunch of changes to the DHCP server. You also need to start paying attention to ICMP. The documentation for ESP-IDF (https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/lwip.html?highlight=CONFIG_LWIP_IPV6 https://docs.espressif.com/projects/esp-idf/en/latest/esp32/...) says: > Disabling CONFIG_LWIP_IPV6 can save about 39 KB for firmware size and 2 KB RAM when the system is powered up and 7 KB RAM when the TCP/IP stack is running. If there is no requirement for supporting IPV6, it can be disabled to save flash and RAM footprint. > Disabling CONFIG_LWIP_IPV4 can save about 26 KB of firmware size and 600 B RAM on power up and 6 KB RAM when the TCP/IP stack is running. If the local network supports IPv6-only configuration, IPv4 can be disabled to save flash and RAM footprint. IPv6 takes up more ROM than IPv4, and as far as I know ESP-IDF doesn't actually fully support IPv6 either. At this point we're talking microcents of storage, but unfortunately the 13KB of size difference can make the difference between "the code fits" and "we need to spend a dollar more per unit".
  - loup-vaillant 3y ago
    My it really is kilobytes. Okay I guess my next project will be a TCP-IP stack on an 32-bit RISC-V micro-controller, we’ll see how much code this actually requires. My understanding of IP may be off, but I still feel those numbers are about an order of magnitude bigger than they actually need to be. I mean, I can fit an entire cryptographic library¹ in 65Kib of RV32IC object code, and it’s not even particularly optimised for this use case. There’s no way the overhead of supporting IPv6 has to be that big. [1]: https://monocypher.org https://monocypher.org
    - 3y ago