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sola969
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Who can use ipv6 normally?

Wed Feb 19, 2020 12:32 am

In China Mobile's broadband IPv6, using the ipv6 routing that comes with the optical cat and the dial-up of router systems such as Padavan can be used perfectly.
Why on ROS, win10 can't get ipv6 DNS, and most websites can't be opened, it's stuck, the website is normal after ipv6 is turned off.
 
sola969
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Re: Who can use ipv6 normally?

Wed Feb 19, 2020 12:36 am

When ROS redials to obtain the new IPv6, Win10 can obtain the new IPv6 address, but Win10 still uses the old IPv6 address.
Using another router system, win10 can obtain the new IPv6 address and can use it normally.
 
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Anumrak
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Re: Who can use ipv6 normally?

Fri Feb 21, 2020 4:38 pm

Hey. Unfortunately, ROS used to use IPv6 RA only to advertise DNS servers for IPv6 hosts. DHCPv6 not working as I know. Win 10 doesn't understand IPv6 RA to grab DNS dynamically. So, you should just write them by hand.
 
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Re: Who can use ipv6 normally?

Fri Feb 21, 2020 5:24 pm

Win10 can get DNS from RA for few years now, but it seems to do it for IPv6-only networks, not when there's IPv4 available too.

I didn't test lately if RouterOS handles changed prefix correctly (the old one needs to be advertised with zero lifetime), but I think I've seen someone complaining about that recently, so maybe it still doesn't.
 
mducharme
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Re: Who can use ipv6 normally?

Fri Feb 21, 2020 7:51 pm

Hi,

RouterOS can advertise DNS with DHCPv6. You simply need to add a DHCPv6 server onto the subnet and enable the "other configuration" flag in IPv6 ND settings, you don't need an IPv6 pool etc. The windows clients will make a DHCPv6 request to get DNS servers.

If Windows 10 receives DNS servers through both RA and DHCP or DHCPv6, it will ignore the DNS servers in the RA and trust the ones from DHCP or DHCPv6 instead. So the solution is to add a DHCPv6 server onto the bridge or whatever the internal network interface is.
 
sola969
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Re: Who can use ipv6 normally?

Sun Feb 23, 2020 11:55 pm

Hi,

RouterOS can advertise DNS with DHCPv6. You simply need to add a DHCPv6 server onto the subnet and enable the "other configuration" flag in IPv6 ND settings, you don't need an IPv6 pool etc. The windows clients will make a DHCPv6 request to get DNS servers.

If Windows 10 receives DNS servers through both RA and DHCP or DHCPv6, it will ignore the DNS servers in the RA and trust the ones from DHCP or DHCPv6 instead. So the solution is to add a DHCPv6 server onto the bridge or whatever the internal network interface is.
This method is very good, win10 did get dns.
However, ipv6 is still abnormal. Many websites cannot be opened or are stuck. Using Padavan's ipv6 is normal, and all websites can be opened normally.
Can a friend use ros's IPv6 to access the website?
 
mducharme
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Re: Who can use ipv6 normally?

Mon Feb 24, 2020 7:36 pm

This method is very good, win10 did get dns.
However, ipv6 is still abnormal. Many websites cannot be opened or are stuck. Using Padavan's ipv6 is normal, and all websites can be opened normally.
Can a friend use ros's IPv6 to access the website?
Yes, the original issue is not related to DNS at all I don't think. IPv4 DNS servers will return AAAA records, so there is no real difference between using IPv4 vs IPv6 DNS servers - either can resolve either type of address with no impact on connectivity, and so using the "wrong" protocol for DNS would not result in any connectivity issues like you describe.

Try a ping to a known pingable IPv6 address like Google DNS (2001:4860:4860::8888). If that fails, then you probably do not have IPv6 routing - either your device is missing the default route to get to the ISP, or the ISP is not installing the route back to you (or is installing an incorrect route). Is your ISP providing IPv6 via DHCP-PD or statically? If it is DHCP-PD you may not have set up the DHCPv6 client, which would result in the ISP not having a route back to you to get the reply data back. If it is static, the ISP may expect your router to be on a specific link-local address like fe80::2. If it requires a specific link-local, this is not possible with RouterOS currently. Being on the wrong link local in this case would result in the packet delivery not making it back to your router.
 
sola969
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Re: Who can use ipv6 normally?

Tue Feb 25, 2020 12:57 am

This method is very good, win10 did get dns.
However, ipv6 is still abnormal. Many websites cannot be opened or are stuck. Using Padavan's ipv6 is normal, and all websites can be opened normally.
Can a friend use ros's IPv6 to access the website?
Yes, the original issue is not related to DNS at all I don't think. IPv4 DNS servers will return AAAA records, so there is no real difference between using IPv4 vs IPv6 DNS servers - either can resolve either type of address with no impact on connectivity, and so using the "wrong" protocol for DNS would not result in any connectivity issues like you describe.

Try a ping to a known pingable IPv6 address like Google DNS (2001:4860:4860::8888). If that fails, then you probably do not have IPv6 routing - either your device is missing the default route to get to the ISP, or the ISP is not installing the route back to you (or is installing an incorrect route). Is your ISP providing IPv6 via DHCP-PD or statically? If it is DHCP-PD you may not have set up the DHCPv6 client, which would result in the ISP not having a route back to you to get the reply data back. If it is static, the ISP may expect your router to be on a specific link-local address like fe80::2. If it requires a specific link-local, this is not possible with RouterOS currently. Being on the wrong link local in this case would result in the packet delivery not making it back to your router.
QQ截图20200225084557.png
The problem was found. The original webpage was stuck due to the default MTU of the ND. Change it to the MTU value obtained by the pppoe client, and everything is normal.
However, on win10, the ros pppoe client disconnects and reconnects to obtain the new ipv6 prefix. Win10 can obtain the new ipv6 prefix. However, it cannot be used. Pinging any ipv6 address is unreachable. Only the local connection of win10 can be reconnected. Normal use. I'm not sure if this is a bug, or it can be solved by changing the parameters like the above problem.
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sola969
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Re: Who can use ipv6 normally?

Tue Feb 25, 2020 10:28 pm

This method is very good, win10 did get dns.
However, ipv6 is still abnormal. Many websites cannot be opened or are stuck. Using Padavan's ipv6 is normal, and all websites can be opened normally.
Can a friend use ros's IPv6 to access the website?
Yes, the original issue is not related to DNS at all I don't think. IPv4 DNS servers will return AAAA records, so there is no real difference between using IPv4 vs IPv6 DNS servers - either can resolve either type of address with no impact on connectivity, and so using the "wrong" protocol for DNS would not result in any connectivity issues like you describe.

Try a ping to a known pingable IPv6 address like Google DNS (2001:4860:4860::8888). If that fails, then you probably do not have IPv6 routing - either your device is missing the default route to get to the ISP, or the ISP is not installing the route back to you (or is installing an incorrect route). Is your ISP providing IPv6 via DHCP-PD or statically? If it is DHCP-PD you may not have set up the DHCPv6 client, which would result in the ISP not having a route back to you to get the reply data back. If it is static, the ISP may expect your router to be on a specific link-local address like fe80::2. If it requires a specific link-local, this is not possible with RouterOS currently. Being on the wrong link local in this case would result in the packet delivery not making it back to your router.
QQ截图20200225084557.png
The problem was found. The original webpage was stuck due to the default MTU of the ND. Change it to the MTU value obtained by the pppoe client, and everything is normal.
However, on win10, the ros pppoe client disconnects and reconnects to obtain the new ipv6 prefix. Win10 can obtain the new ipv6 prefix. However, it cannot be used. Pinging any ipv6 address is unreachable. Only the local connection of win10 can be reconnected. Normal use. I'm not sure if this is a bug, or it can be solved by changing the parameters like the above problem.
Changing the MTU to 1480 can only be said to be 80% better, and there are some website pictures that cannot be displayed, such as Tencent videos on the Android platform.
The ipv6 MTU obtained by using Padavan in win10 is 1500, everything is normal on the network, and normal on Android.
Why does ros need to be changed to 1480 to get a good 80%?
 
idlemind
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Re: Who can use ipv6 normally?

Sat Feb 29, 2020 11:20 pm

If lowering the MTU helps it generally points to bad firewall rules that are blocking path MTU discovery. If you lower it further to 1280 and you see additional sites work that would confirm the issue. The fix would be to ensure you are allowing the correct ICMPv6 traffic through the firewall.

It's not uncommon to experience MTU drops over the different paths of the Internet. In IPv4 the respective router handles the fragmentation. In IPv6 it's the responsibility of the client to hear the message that fragmentation is required and to perform the fragmentation.
 
sola969
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Re: Who can use ipv6 normally?

Sat Feb 29, 2020 11:43 pm

If lowering the MTU helps it generally points to bad firewall rules that are blocking path MTU discovery. If you lower it further to 1280 and you see additional sites work that would confirm the issue. The fix would be to ensure you are allowing the correct ICMPv6 traffic through the firewall.

It's not uncommon to experience MTU drops over the different paths of the Internet. In IPv4 the respective router handles the fragmentation. In IPv6 it's the responsibility of the client to hear the message that fragmentation is required and to perform the fragmentation.
The ipv6 firewall itself is all turned off, and the MTU is changed to 1280, so the problem can't be found.
 
mducharme
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Re: Who can use ipv6 normally?

Thu Mar 05, 2020 8:19 pm

The ipv6 firewall itself is all turned off, and the MTU is changed to 1280, so the problem can't be found.
Hi, your ISP may somehow be blocking the ICMPv6 from reaching the destination, or possibly your computer is doing something with it.

You are connecting over PPPoE - when you connect with the Padavan router, what is the MTU for the PPPoE itself? Not talking about internal MTU.

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