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My ISP doesn't support IPv6 and it's been complicated to get IPv6 running properly at my hosting providers too. My hosting provider uses DHCP to propagate routi

by kuon 9y ago

My ISP doesn't support IPv6 and it's been complicated to get IPv6 running properly at my hosting providers too. My hosting provider uses DHCP to propagate routing information, and I had a lot of issue with it going down, thus losing IPv6 connectivity. In the end I just disabled IPv6 on all the node I manage, it has no benefit except increased complexity. The problem is the lack of insensitive to do the conversion.

XorNot 9y ago
This sounds more like poor DHCP configuration on your side? DHCP going down doesn't remove anything unless your client decides to time out it's current address configuration - of which there's no incentive to do on a server. Moreover if routing was being propagated by DHCP, why was that not the case for IPv4 as well which would presumably be using it ?
- geofft 9y ago
  DHCPv4 and DHCPv6 are different (they even run on different ports) and probably they have more experience with monitoring and operating DHCPv4. Honestly I think the fundamental mistake of IPv6 was trying to fix everything else along the way. Certainly there are things that can be fixed in DHCPv4. But there isn't a way to put off that operational work until you're ready to get good at it; there is no way to just get more addresses and not also sign up to run a new version of DHCP, to decide if you even want DHCPv6 or you want RAs and SLAAC, to give up ARP, etc. It's a big lesson in the second system effect.
  - pas 9y ago
    What was the problem with ARP anyway? Why Neighbor Discovery is better?
    - geofft 9y ago
      As I understand it, ARP is abstraction-breaking and hard-codes that IP is running on top of Ethernet or something Ethernet-compatible - you're sending Ethernet packets (with a non-IP EtherType) that reference IP and an IP address, initially over Ethernet broadcast. NDP runs over ICMPv6, which is an IP protocol, and the way it works is that it's sent to well-known IPv6 multicast addresses, ff02::1 for all nodes or ff02::2 for all routers. If you're a node and/or a router, you join those multicast groups. So there's no assumption of Ethernet; that just depends on some link layer with a working multicast. (And broadcast is a perfectly legal implementation of multicast, although if your layer 2 protocol makes it easy to do a better implementation, great.) Also, there's some multicast fanciness so you join a multicast group based on some hash of your IP address so that NDP packets don't even go to all machines, but just some hash bucket that contains that IP address. (I think these are good reasons to make a successor to ARP, but I don't think these are good reasons to require that you use the successor protocol if you don't want to NAT, especially given the extent to which deployed networking gear does ARP snooping and IGMP snooping - and does not expect a pile of multicast groups.)
- kuon 9y ago
  That's what I thought too, I really tried a lot of configuration client side, on different OS (linux, bsd...), but none was working reliably, even the provider preconfigured linux image. It might be client that are all broken or something else, to be honest I didn't investigate it further, as I don't need IPv6, I just wanted to be "ready" for the future.
dijit 9y ago
incentive* and yes, I agree. I actually tell my ISP when they call me to upgrade that I will not upgrade to a higher package unless that package has IPv6 enabled. I am probably the only person who does this. What I did instead was set up a HE.net tunnel so I can actually have IPv6 (albeit with a smaller MTU, but you're unlikely to notice). What I gain is the ability to run my own little services at home again, no NAT punching! no complicated rules.. I have a salt master that connects to my IPV6 enabled VPS' (which is all of them, thankfully), I have all my mail listening on VPS's with IPv4 and IPv6 which take in my mail and deliver it to a harddisk at my house essentially. Anything S2S can happen directly.. and it's nicer even on IPv6 enabled networks that I happen to be on when travelling (Mobile operators are increasingly IPv6).. But it's unreliable to be IPv6 only, I can only access my home from other wifi networks at a ratio of about 1:20.. But I long for the day where it's ubiquitous and I can shit on wifi operators for not supporting it.. that day will come. I mean last year IPv6 adoption more than doubled and is sitting at around 22%~ of all traffic.. so that's something.
- deleted 9y ago
  [deleted]

by kuon 9y ago

XorNot 9y ago

This sounds more like poor DHCP configuration on your side? DHCP going down doesn't remove anything unless your client decides to time out it's current address configuration - of which there's no incentive to do on a server. Moreover if routing was being propagated by DHCP, why was that not the case for IPv4 as well which would presumably be using it ?

geofft 9y ago
DHCPv4 and DHCPv6 are different (they even run on different ports) and probably they have more experience with monitoring and operating DHCPv4. Honestly I think the fundamental mistake of IPv6 was trying to fix everything else along the way. Certainly there are things that can be fixed in DHCPv4. But there isn't a way to put off that operational work until you're ready to get good at it; there is no way to just get more addresses and not also sign up to run a new version of DHCP, to decide if you even want DHCPv6 or you want RAs and SLAAC, to give up ARP, etc. It's a big lesson in the second system effect.
- pas 9y ago
  What was the problem with ARP anyway? Why Neighbor Discovery is better?
  - geofft 9y ago
    As I understand it, ARP is abstraction-breaking and hard-codes that IP is running on top of Ethernet or something Ethernet-compatible - you're sending Ethernet packets (with a non-IP EtherType) that reference IP and an IP address, initially over Ethernet broadcast. NDP runs over ICMPv6, which is an IP protocol, and the way it works is that it's sent to well-known IPv6 multicast addresses, ff02::1 for all nodes or ff02::2 for all routers. If you're a node and/or a router, you join those multicast groups. So there's no assumption of Ethernet; that just depends on some link layer with a working multicast. (And broadcast is a perfectly legal implementation of multicast, although if your layer 2 protocol makes it easy to do a better implementation, great.) Also, there's some multicast fanciness so you join a multicast group based on some hash of your IP address so that NDP packets don't even go to all machines, but just some hash bucket that contains that IP address. (I think these are good reasons to make a successor to ARP, but I don't think these are good reasons to require that you use the successor protocol if you don't want to NAT, especially given the extent to which deployed networking gear does ARP snooping and IGMP snooping - and does not expect a pile of multicast groups.)
kuon 9y ago
That's what I thought too, I really tried a lot of configuration client side, on different OS (linux, bsd...), but none was working reliably, even the provider preconfigured linux image. It might be client that are all broken or something else, to be honest I didn't investigate it further, as I don't need IPv6, I just wanted to be "ready" for the future.

dijit 9y ago

incentive* and yes, I agree. I actually tell my ISP when they call me to upgrade that I will not upgrade to a higher package unless that package has IPv6 enabled. I am probably the only person who does this. What I did instead was set up a HE.net tunnel so I can actually have IPv6 (albeit with a smaller MTU, but you're unlikely to notice). What I gain is the ability to run my own little services at home again, no NAT punching! no complicated rules.. I have a salt master that connects to my IPV6 enabled VPS' (which is all of them, thankfully), I have all my mail listening on VPS's with IPv4 and IPv6 which take in my mail and deliver it to a harddisk at my house essentially. Anything S2S can happen directly.. and it's nicer even on IPv6 enabled networks that I happen to be on when travelling (Mobile operators are increasingly IPv6).. But it's unreliable to be IPv6 only, I can only access my home from other wifi networks at a ratio of about 1:20.. But I long for the day where it's ubiquitous and I can shit on wifi operators for not supporting it.. that day will come. I mean last year IPv6 adoption more than doubled and is sitting at around 22%~ of all traffic.. so that's something.

deleted 9y ago
[deleted]