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JHV
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DHCPv6-client broken since v6.34

Sun Jun 19, 2016 4:21 pm

The problem was described in several posts within this thread in February 2016 and the last working version was v 6.33.6.
The last tested version is 6.36.rc28 but without success.
Hardware is RB751G-2HnD.

The German ISP 1&1 delivers dual stack IPv6 with dynamically IPv6 prefixes over DHCPv6. These prefixes will be changed after 24 hours and whenever a disconnect occurs. Until ROS v. 6.33.6 the reacquisition of a changed prefix was done almost instantly.
/ipv6 dhcp-client> print detail
Flags: D - dynamic, X - disabled, I - invalid 
 0    interface=pppoe-out1 status=bound duid="0x00030001000c42fcb86c" 
      dhcp-server-v6=fe80::32f7:dff:fe7f:7600 request=prefix 
      add-default-route=yes use-peer-dns=no pool-name="ppppool6" 
      pool-prefix-length=64 prefix-hint=::/0 
      prefix=2003:46:33a:ce00::/56, 3h54m43s
Since ROS v. 6.34 the DHCPv6 client hangs in state "renewing" for exactly 10 minutes.
/ipv6 dhcp-client> print detail
Flags: D - dynamic, X - disabled, I - invalid 
 0    interface=pppoe-out1 status=renewing... duid="0x00030001000c42fcb86c" 
      dhcp-server-v6=fe80::32f7:dff:fe7f:7600 request=prefix 
      add-default-route=yes use-peer-dns=no pool-name="ppppool6" 
      pool-prefix-length=64 prefix-hint=::/0 
      prefix=2003:46:33a:ce00::/56, 3h58m34s 
After that the status changes for another 10 minutes to "rebinding".
/ipv6 dhcp-client> print detail
Flags: D - dynamic, X - disabled, I - invalid 
 0    interface=pppoe-out1 status=rebinding... duid="0x00030001000c42fcb86c" 
      dhcp-server-v6=fe80::32f7:dff:fe7f:7600 request=prefix 
      add-default-route=yes use-peer-dns=no pool-name="ppppool6" 
      pool-prefix-length=64 prefix-hint=::/0 
      prefix=2003:46:33a:ce00::/56, 3h48m33s 
So it takes always 20 minutes until the new prefix is available and can be distributed to the clients.
 
JHV
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Re: DHCPv6-client broken since v6.34

Sat Jul 02, 2016 2:36 pm

A few more thoughts at this topic.

Patch 6.34 has introduced a few changes regarding to the DHCPv6-client. Since then the client does no longer work as expected. After a connection lost on WAN side, the DHCPv6-client tries a renewing attempt followed by a rebinding attempt.  Each attempt takes exactly 600 seconds and has, of course, no success. Renewing and rebinding can't work since the old prefix is immediately invalid after a PPPoE dis-/reconnect occurs.

These 600 seconds are described in RFC3315 as "REN_MAX_RT" (Max Renew timeout value) or "REB_MAX_RT" (Max Rebind timeout value). It seems to be clear, that the router sends only these two messages to the DHCPv6 server located at ISP side.
Therefore my question is, why sends the Mikrotik router renewing/rebinding messages after losing  and regaining the PPPoE connection, instead of a solicit/request message? 
 
JHV
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Re: DHCPv6-client broken since v6.34

Sat Jul 09, 2016 11:39 pm

Any confirmation about this issue would be much appreciated. 
I  doubt I'm the only one who uses Mikrotik routers in networks with dynamically assigned IPv6 prefixes.
 
Jan89
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Re: DHCPv6-client broken since v6.34

Tue Jul 12, 2016 6:04 pm

In version v6.35.4 dhcp-v6 client with prefixes started working in my router :)
 
JHV
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Re: DHCPv6-client broken since v6.34

Sun Jul 17, 2016 1:06 am

In version v6.35.4 dhcp-v6 client with prefixes started working in my router :)
What do you mean with "started working"? The DHCPv6 client works since ages, but not anymore in networks with dynamically assigned prefixes.
Does your provider enforce a disconnect every 24 hours? Do you get always a new prefix after such a compulsory disconnect? If not, the DHCPv6 client works fine indeed.
Btw: Latest tested version is 6.36rc40 and the issue still exists. 
 
_saik0
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Re: DHCPv6-client broken since v6.34

Sun Oct 02, 2016 3:01 pm

Wait what?

A dynamic PD with 24hr reset and every time you are assigned a different v6 prefix?
Is your ISP stupid or what?
 
Jan89
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Re: DHCPv6-client broken since v6.34

Wed Oct 05, 2016 3:43 pm

In version v6.35.4 dhcp-v6 client with prefixes started working in my router :)
What do you mean with "started working"? The DHCPv6 client works since ages, but not anymore in networks with dynamically assigned prefixes.
Does your provider enforce a disconnect every 24 hours? Do you get always a new prefix after such a compulsory disconnect? If not, the DHCPv6 client works fine indeed.
Btw: Latest tested version is 6.36rc40 and the issue still exists. 
Started working with dynamically assigned prefixes. :)
My ISP gives me /56 of IPv6 addresses
 
pe1chl
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Re: DHCPv6-client broken since v6.34

Wed Oct 05, 2016 3:49 pm

Wait what?

A dynamic PD with 24hr reset and every time you are assigned a different v6 prefix?
Is your ISP stupid or what?
Yes, it is really stupid to do that. To be able to live with that you would need 1:1 NAT for IPv6 which MikroTik does not provide.
I think it is popular to do this in Germany, where there has been a tradition of daily address changes in IPv4 as well.
I seem to recall that it was initially done "for privacy" (to avoid companies being able to link a certain IP address to a certain user)
but of course by now that has no merit anymore as enough tricks and methods have been developed to work around that.

In networking, it is a real pain. It should at least be optional...

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