IPv6 woes after last Emegency Maintenence in June

[daverand]

This has been an ongoing issue. I am able to get an interface IPv6 address, but not IA_PD.

Jun 18 10:41:22 main10 dhcp6c[74677]: reset a timer on ix0, state=RENEW, timeo=0
, retrans=10507
Jun 18 10:41:22 main10 dhcp6c[74677]: Sending Renew
Jun 18 10:41:22 main10 dhcp6c[74677]: a new XID (f6e75c) is generated
Jun 18 10:41:22 main10 dhcp6c[74677]: set client ID (len 10)
Jun 18 10:41:22 main10 dhcp6c[74677]: set server ID (len 26)
Jun 18 10:41:22 main10 dhcp6c[74677]: set IA address
Jun 18 10:41:22 main10 dhcp6c[74677]: set identity association
Jun 18 10:41:22 main10 dhcp6c[74677]: set elapsed time (len 2)
Jun 18 10:41:22 main10 dhcp6c[74677]: set option request (len 4)
Jun 18 10:41:22 main10 dhcp6c[74677]: send renew to ff02::1:2%ix0
Jun 18 10:41:22 main10 dhcp6c[74677]: receive reply from fe80::da53:9aff:fe0b:f956%ix0 on ix0
Jun 18 10:41:22 main10 dhcp6c[74677]: get DHCP option client ID, len 10
Jun 18 10:41:22 main10 dhcp6c[74677]: DUID: 00:03:00:01:d4:20:00:b0:ec:cd
Jun 18 10:41:22 main10 dhcp6c[74677]: get DHCP option server ID, len 26
Jun 18 10:41:22 main10 dhcp6c[74677]: DUID: 00:02:00:00:05:83:64:38:3a:35:33:3a:39:61:3a:30:62:3a:66:39:3a:35:36:00:00:00
Jun 18 10:41:22 main10 dhcp6c[74677]: get DHCP option identity association, len 40
Jun 18 10:41:22 main10 dhcp6c[74677]: IA_NA: ID=0, T1=10800, T2=17280
Jun 18 10:41:22 main10 dhcp6c[74677]: get DHCP option IA address, len 24
Jun 18 10:41:22 main10 dhcp6c[74677]: IA_NA address: 2001:5a8:601:23::135 pltime=21600 vltime=21600
Jun 18 10:41:22 main10 dhcp6c[74677]: get DHCP option DNS, len 32
Jun 18 10:41:22 main10 dhcp6c[74677]: dhcp6c Received INFO
Jun 18 10:41:22 main10 dhcp6c[74677]: nameserver[0] 2001:5a8::11
Jun 18 10:41:22 main10 dhcp6c[74677]: nameserver[1] 2001:5a8::33
Jun 18 10:41:22 main10 dhcp6c[74677]: update an IA: NA-0
Jun 18 10:41:22 main10 dhcp6c[74677]: update an address 2001:5a8:601:23::135 pltime=21600, vltime=70136815965280
Jun 18 10:41:22 main10 dhcp6c[74677]: add an address 2001:5a8:601:23::135/128 on ix0

Everything is good. No problem there.

But when I attempt to get the IA_PD?


Jun 18 10:23:31 main10 dhcp6c[74677]: Sending Solicit
Jun 18 10:23:31 main10 dhcp6c[74677]: set client ID (len 10)
Jun 18 10:23:31 main10 dhcp6c[74677]: set elapsed time (len 2)
Jun 18 10:23:31 main10 dhcp6c[74677]: set option request (len 4)
Jun 18 10:23:31 main10 dhcp6c[74677]: set IA_PD prefix
Jun 18 10:23:31 main10 dhcp6c[74677]: set IA_PD
Jun 18 10:23:31 main10 dhcp6c[74677]: send solicit to ff02::1:2%ix0
Jun 18 10:23:31 main10 dhcp6c[74677]: reset a timer on ix0, state=SOLICIT, timeo=1260, retrans=120864
Jun 18 10:23:31 main10 dhcp6c[74677]: receive advertise from fe80::da53:9aff:fe0b:f956%ix0 on ix0
Jun 18 10:23:31 main10 dhcp6c[74677]: get DHCP option client ID, len 10
Jun 18 10:23:31 main10 dhcp6c[74677]: DUID: 00:03:00:01:d4:20:00:b0:ec:cd
Jun 18 10:23:31 main10 dhcp6c[74677]: get DHCP option server ID, len 26
Jun 18 10:23:31 main10 dhcp6c[74677]: DUID: 00:02:00:00:05:83:64:38:3a:35:33:3a:39:61:3a:30:62:3a:66:39:3a:35:36:00:00:00
Jun 18 10:23:31 main10 dhcp6c[74677]: get DHCP option IA_PD, len 48
Jun 18 10:23:31 main10 dhcp6c[74677]: IA_PD: ID=0, T1=0, T2=0
Jun 18 10:23:31 main10 dhcp6c[74677]: get DHCP option status code, len 32
Jun 18 10:23:31 main10 dhcp6c[74677]: status code: no prefixes
Jun 18 10:23:31 main10 dhcp6c[74677]: get DHCP option DNS, len 32
Jun 18 10:23:31 main10 dhcp6c[74677]: server ID: 00:02:00:00:05:83:64:38:3a:35:33:3a:39:61:3a:30:62:3a:66:39:3a:35:36:00:00:00, pref=-1
Jun 18 10:23:31 main10 dhcp6c[74677]: advertise contains no address/prefix

I am requesting a /56 (I tried requesting a /64 PD as well). When you reply, I get “status code: no prefixes”. I suspect this means that the DHCP server for the segment of your network that I have been allocated is either out of IPv6 prefixes in its pool, or that it’s not configured to give IA_PDs.

When I was first connected to the Sonic network, this was in fact the case, and you had to adjust the DHCP server before I was handed an address. I suspect whatever change you did recently has placed me on another segment of your network, or changed which DHCP server I talk to, and is no longer handing out addresses. As a reminder, this had been working fine for months prior to the recent change.

[sommerfeld]

I just brought up prefix delegation with Sonic for the first time this evening; the client sent both IA_NA and IA_PD in a single Solicit message and used a Type 1 DUID for its client id; it got a delegation the first time it asked.

You might want to take a look at viewtopic.php?t=17819&start=10#p63957 :

The platform upstream of Sonic's fiber platform cannot support a router that does stateful address assignment (DHCPv6) by sending two separate Solicit messages for IA_NA and IA_PD assignments using DUID Type 2 or DUID Type 3 generation. This is a very specific restriction that most routers will not run into or can work around.

The logs you posted look to me like your DHCPv6 client is doing the unsupported combination: sending separate Solicit messages for IA_NA and IA_PD while using a Type 3 client ID. Not sure which of those two things is easier for you to change in your DHCPv6 client. Hope this helps..

[daverand]

That's a good thought. I'll again state the configuration was working prior to the maintenance.

So, I dropped the interface address request, and now am requesting only the prefix.
Jul 8 04:28:19 main10 dhcp6c[76791]: Sending Solicit
Jul 8 04:28:19 main10 dhcp6c[76791]: set client ID (len 10)
Jul 8 04:28:19 main10 dhcp6c[76791]: set elapsed time (len 2)
Jul 8 04:28:19 main10 dhcp6c[76791]: set option request (len 4)
Jul 8 04:28:19 main10 dhcp6c[76791]: set IA_PD prefix
Jul 8 04:28:19 main10 dhcp6c[76791]: set IA_PD
Jul 8 04:28:19 main10 dhcp6c[76791]: send solicit to ff02::1:2%ix0

But no joy, when requesting a /56 PD:

Jul 8 04:28:19 main10 dhcp6c[76791]: get DHCP option client ID, len 10
Jul 8 04:28:19 main10 dhcp6c[76791]: DUID: 00:03:00:01:d4:20:00:b0:ec:cd
Jul 8 04:28:19 main10 dhcp6c[76791]: get DHCP option server ID, len 26
Jul 8 04:28:19 main10 dhcp6c[76791]: DUID: 00:02:00:00:05:83:64:38:3a:35:33:
3a:39:61:3a:30:62:3a:66:39:3a:35:36:00:00:00
Jul 8 04:28:19 main10 dhcp6c[76791]: get DHCP option IA_PD, len 48
Jul 8 04:28:19 main10 dhcp6c[76791]: IA_PD: ID=0, T1=0, T2=0
Jul 8 04:28:19 main10 dhcp6c[76791]: get DHCP option status code, len 32
Jul 8 04:28:19 main10 dhcp6c[76791]: status code: no prefixes
Jul 8 04:28:19 main10 dhcp6c[76791]: get DHCP option DNS, len 32
Jul 8 04:28:19 main10 dhcp6c[76791]: server ID: 00:02:00:00:05:83:64:38:3a:35:33:3a:39:61:3a:30:62:3a:66:39:3a:35:36:00:00:00, pref=-1
Jul 8 04:28:19 main10 dhcp6c[76791]: advertise contains no address/prefix

To clarify further - I have two other providers on this router, happily providing IPv6 via DHCP. I have my own IPv6 block, and am routing fine on that.

[daverand]

And to answer my own post, thanks to @sommerfeld, the solution was to configure DUID-LLT. Even though it took a while, I did finally get both an IA and PD, and I'm back up with full IPv6.

So - you absolutely need DUID-LLT!

Thank you!

[sommerfeld]

And to answer my own post, thanks to @sommerfeld, the solution was to configure DUID-LLT. Even though it took a while, I did finally get both an IA and PD, and I'm back up with full IPv6.

So - you absolutely need DUID-LLT!

Thank you!

You're welcome! Glad that my suggestion actually worked.

(The timing of your responses has me wondering whether there's also a ~6 hour lease timeout involved here - not only do you need to ask for PD+IA leases in precisely the right way, you also have to wait for a "wrong" lease to time out after you ask the wrong way..).

[klui]

How did it work before? Or is this a new change by Sonic?

[daverand]

Good question. It was functional before the change, and non-functional after, back in June.

It "came good" at Jul 8 07:44:48, yet my last change to my config was Jul 8 05:41 /var/etc/dhcp6c.conf.

Was it timeout? Was a change made to the DHCP6 server?

Don't know - but I'm happy that it's back. I depend on v6, and I'm happier I no longer have to route through one of my other providers.

[max.b]

Thank you Sommerfeld for taking the time to respond with such helpful info. Glad you all were able to get it worked out! As for your question Daverand on why things changed, I know we are doing a lot of work currently regarding IPv6 and updates are being made all the time. I am currently not sure exactly what would have changed in this case, but I will reach out to our network engineers and provide an update here as soon as I have one. Hope you all have a great weekend in the meantime!

[max.b]

Hello,
Quick follow up. I heard back from our network engineers and this has apparently been a limitation for quite some time and has not changed recently so I'm actually not sure how this was working for you previously. Sorry I couldn't provide a more detailed answer, but I am glad at least everything is working for you now. Please let me know if you have any follow up questions. Take care!