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Problem with expiring IPv6 addresses

Fri Nov 29, 2019 12:49 am

Hello, I noticed a rather strange problem with the IPv6 address in the "LAN" network. The problem mainly concerns devices using WLAN. Some time after connecting the device loses communication via IPv6, they also disappear from neighbors on the mikrotik.
The only solution is to disconnect from the network and reconnect.

Did something have a similar problem?

I thought about pinging ff02::1 every few minutes. However, this seems more a workaround than a solution to the problem.

Thank You in advice.
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Re: Problem with expiring IPv6 addresses

Fri Nov 29, 2019 9:17 am

I'm guessing you're using ND mechanism for setting IPv6 addresses on your LAN.

If this is so, then you might want to check settings under /ipv6 nd ... there are at least two settings that might be relevant in your case: ra-lifetime and ra-interval.

I'm also guessing that some wireless devices go to sleep and miss several RA (routing announcement) transmissions ... enough to hit the ra-lifetime limit. You may want to shorten the ra-interval to something around 1 minute, which will make chances that sleeping beauty catches an RA before ra-lifetime expires.
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Re: Problem with expiring IPv6 addresses

Fri Nov 29, 2019 11:17 am

I'd advise to not use something that short.
RFC 7772 (Reducing Energy Consumption of Router Advertisements) advises to not send more than 7 RAs per hour.
Something else might be broken in your config.
These are my settings that work just fine.
/ipv6 nd
set [ find default=yes ] ra-interval=8m34s-11m26s ra-lifetime=1h
/ipv6 nd prefix default
set preferred-lifetime=30m valid-lifetime=1h

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