Hello everyone,

Heise sent 25 routers into the IPv6 test (behind paywall):

• "IPv6 is now essential. But some routers already fail to provide Internet via IPv6. We tested 25 devices in four scenarios."

• https://www.heise.de/tests/25-Router-im ... 49159.html

And there is this statement in the opening text:

• "Mikrotik was eliminated early in the acquisition process because their routers still do not cleanly handle dynamic IPv6 prefixes since 2013."

So I thought I'd ask around and see what you guys think on this...?

Not enough context to comment on this. What was tested and what exactly failed?

When I used an Asus router (both merlin and freshtomato firmware), I could get IPv6 to work somewhat, though it had issues. When I switched to a TP-Link router, I couldn't get IPv6 to work reliably at all (same with openwrt). I got the Mikrotik for the purpose of better IPv6 support. It works well, where the others fail.

So I thought I'd ask around and see what you guys think on this...?

It's a shit article.
What do you think about this?

Yes, RouterOS can't deprecate old prefixes unless you write a fancy script for it.
Yes, you can't set a prefix hint.
Other stuff I can't remember right now.
Oh yeah, they can't fix an year old bug regarding IPv6 and Wireguard.

But "it works".

It´s an article for simple users, who don´t write any scripts, but expect IPv6 to work out of box.
In Germany (which is also true for Austrisa and most of Hungary) the major providers will reassign you a new IPv6 prefix at least every night. Don´t know the exact reason why they are doing this, but probably to "encourage" businesses not to use cheap subscriptions.

If you get a new IPv6 prefix, your IPv6 connection just breaks from the users perspective every night. So CT which is technical magazine with strong orientation towards hobbyists, did not include MT in his tests, explicitly mentioning, that this issue was not adressed since many years by MT.

It´s not so great publicity for M. But the only bad news is: if there are no news at all....

The exact nature of this issue was discussed here already:
viewtopic.php?p=975818&hilit=dynamic+ipv6#p975818

Yes, you can't set a prefix hint.

But you can:
It's a hint (so DHCPv6 server can ignore it completely), but if hint is a realistic one (the one in code above is not) it might be taken into account.

My IPv6 prefix doesn't change every night, but it changes sometimes. Maybe once or twice a month. I "fixed" that, not with a script, but by just setting the Preferred Lifetime to 20 minutes, and Valid Lifetime to 12 hours. Even without that, linux and android picked up the new prefix and used it. Only windows insisted on using the old one. This way, it will start using the new one after 20 minutes.

Link to the RIPE IPv6-wg mailing list, where the link to the complete article was posted:
https://www.ripe.net/ripe/mail/archives ... 03835.html

Yes, you can't set a prefix hint.

But you can:

Code:Select all

/ipv6 dhcp-client add interface=WAN pool-name=MyPool prefix-hint=2a00:1450:4014:80e::/56 request=prefix

It's a hint (so DHCPv6 server can ignore it completely), but if hint is a realistic one (the one in code above is not) it might be taken into account.

Not talking about that one.
I'm talking about LAN assignments, you can't choose a specific prefix from the pool.

I'm talking about LAN assignments, you can't choose a specific prefix from the pool.

You can ... as long as it's not biting into same "word" as already containing prefix.

E.g. if you get /40 prefix from ISP, then you can select which the prefix value up to /48.

If you got prefix 3000:aaaa:bb00:/40 from ISP, then

• you can select address :22224444:5555/64 for interface (so you're setting 80 bits of address, 40 are defined by pool prefix, 8 bits are available for random variations) ... IPv6 address will be 3000:aaaa:bb0022224444:5555/64
• 你不能选择地址s ::cc22224444:5555/64 for interface (essentially setting 96 bits) ... that would theoretically set IPv6 address of 3000:aaaa:bbcc22224444:5555/64 but this indeed isn't possible in ROS
• if you set many interfaces with same interface "postfix", e.g. :22224444:5555/64, then ROS will automatically set value of those 8 bits of "randomness" and second interface will get address of 3000:aaaa:bb0122224444:5555/64

So it's not that those extra bits are never gone be used, but it's not possible to use them in deterministic way.

Yes, I'm talking about exactly this:viewtopic.php?p=966400#p966400
Getting /56 from the ISP, btw. This is a more common case anyway.

behind paywall

As mentioned by @Trema in post #8 already, the article is availablewithout paywall as well …

What was tested and what exactly failed?

The author responded to a questionthereand indeedreferences the threadmentioned by @woland in post #5. Even with RouterOS v7 the workaround is a script …

If you noticed the issue at all. Tracking down such an issue is complicated thanks to approaches likeHappy Eyeballs. Furthermore, not everyone uses such an Internet Service Provider. Consequently, you might need to be local to the client setup. How difficult that is, can be seen by the original question there as well: The questioner – although from Germany, referencing a German tutorial for IPv6 in RouterOS – did not know about this ten year old issue. That is the problem with such things, which not only simply not work but are not obvious either (you have to wait 24 hours, need an app without Happy Eyeballs, …).

However, the author mentions a second issue:DHCPv6 Reconfigureis missing. Although this is an optional feature in the RFC, it is somewhat required if there is another router behind or in front of RouterOS, a router cascade. Otherwise, the router behind sits on the previously delegated prefix for ages. And in my tests, indeed, I cannot find DHCPv6 Reconfigure. Neither on the LAN nor the WAN side of my MikroTik. Is there any trick or script to achieve that? It might be possible for RouterOS as the downstream router, when the prefix changes via SLAAC, to ask for a new prefix via DHCPv6. However, when RouterOS is the upstream/frontmost router, is there any way to enable DHCPv6 Reconfigure?

By the way, what I did not learn from any of the referenced threads and posts: Does MikroTik encourage us users to report such issues; should everyone affected by this, create a ticket beside posting in the public forums here? Should we reference the original ticket#2013052766001293 to create a duplicate, or be vague so the support teams understands the issue itself and creating the duplicate itself? Or should we not bother/report at all because it is a confirmed known issue?

You have to put something more to the table than just the "missing DHCPv6 Reconfigure" which is not even mandatory, as you've said.

As English is not my native language, I do not know that idiom, and not sure whether I got your post. Therefore, I try:

I am just translating the two rationales given by the author of that article.

Both issues are around dynamic IPv6 prefixes and the after-reconnection scenario. One issue: With PPPoE, RouterOS does not ditch the previous = outdated IPv6 prefix automatically; as a workaround, a script is required. Another issue is DHCPv6 Reconfigure. Although DHCPv6 Reconfigure is optional in the IETF RFC, it is required in case of a router cascade. The first router gets a new IPv6 prefix (via DHCPv6, SLAAC, or PPPoE … does not matter). Now, the second router is still on the now outdated IPv6 prefix. It cannot access the Internet via that prefix. Without DHCPv6 Reconfigure, the second router is offline until the next DHCPv6 Renew. To shorten that time, DHCPv6 Reconfigure exists, which RouterOS does not offer in the role of DHCPv6 server.

Those issues do not arise if your Internet Service Provider (ISPs) assigns a static IPv6 prefix. Both issues do not arise as long as you do not get a new prefix. For example, in Germany, 1&1 and O₂ disconnect the PPPoE session every 24 hours and assign a different IPv6 prefix afterward. So this affects several ISPs: Telekom Deutschland, 1&1, O₂, and several of the new Fiber ISPs. Furthermore, for a private individual† in Germany, it is impossible to change the contract to a static IPv6 prefix; at least, I am unaware of such an option. Yes, some ISPs re-assign the IPv6 prefix only after the router is offline. Consequently, I would have to switch the ISP or disable IPv6.

My questions:我如何报告这样MikroTik吗?雷竞技网站The first issue is just a change in the protocol flow, correctly changed, the flow works with all existing implementations and adds those ISP as well. The second issue is about a use case that requires a specific feature. Is it sufficient to mention that in the Web forum, MikroTik translates that to internal means? Or, if I have to report it, which way and how should I report it so the use case and its amount of users stay visible?

† Several of the current products of MikroTik are aimed at private individuals as well, like thehAP series. At least that was mentioned in official Webpage and YouTube channel, for example, with the just releasedhAP ax lite甚至没有一个吗Quick Setother than HomeAP anymore. Or am I mistaken?