Bug #45780 for dhcp-public: Fwd: DHCPv6 PD oddity with client changing prefix size.

# Tue, 15 Aug 2017 08:46:04 -0400 Tim DeNike <tim@denike.us> - Ticket created [Reply] [Comment]

To:	dhcp-bugs@isc.org
Date:	Tue, 15 Aug 2017 08:45:50 -0400
Subject:	Fwd: DHCPv6 PD oddity with client changing prefix size.
From:	"Tim DeNike" <tim@denike.us>

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Running 4.3.5 in an ISP environment. Delivering prefixes via DHCPv6-PD.

By default we give users a /64 but will allow them to request a /60 or /56.

Everything works fine with the /64s and /60s EXCEPT if a user changes prefix lengths.

IE: User plugs in and enables DHCPv6, they get a /64. They decide they want a /60 so change their prefix hint to /60 release/renew, they get the same /64 back again.

The only way to get them to acquire a /60 is to either manually remove the /64 lease from the leases file or wait out until the default-lease-time has expired.

Apparently when the client releases the prefix, it is still held for them so they can get it back. No problem with that functionality. Makes sense. But if the client releases and requests a prefix that doesn't have a length that matches the previous lease then they should be allocated a prefix from the pool that does match based on the rules of "prefix-length-mode".

We do have "prefix-length-mode exact;" set.

Seems like a simple oversight/unintended side effect.

Hello Tim:

I retested your scenario with 4.3.6 which we released on 7/31. While it does contain a correction for one issue with prefix delegation it does not address your scenario which I tested as:

1. Configured a server to have two PD pools in the same subnet, one /64 and the other /60, prefix-length-mode = exact

2. Solicits from the same client with prefix length hints of /64 and /60 , are offered leases of /64 and /60, respectively

(confirming hints are being honored as expected)

3. Client solicits a /64, and accepts the offered /64 PD lease

4. Client releases /64 PD lease

5. Client solicits a /60

6. Server offers prior /64 PD lease

(Note prefix value for all solicits was "::")

If you would be so kind as to open a bug for this, we should be able to work it into 4.4.0 which is slated for January '18.

# Tue, 15 Aug 2017 09:20:16 -0400 Thomas Markwalder <tmark@isc.org> - Versions Planned 4.4.0 added

# Tue, 15 Aug 2017 09:20:16 -0400 Thomas Markwalder <tmark@isc.org> - FinalPriority changed from '50' to '30'

# Tue, 15 Aug 2017 09:20:16 -0400 Thomas Markwalder <tmark@isc.org> - Priority changed from '50' to '30'

# Tue, 15 Aug 2017 09:20:16 -0400 Thomas Markwalder <tmark@isc.org> - Queue changed from #8 to dhcp-public

# Wed, 16 Aug 2017 14:27:07 -0400 Thomas Markwalder <tmark@isc.org> - Taken

# Tue, 22 Aug 2017 11:09:25 -0400 Thomas Markwalder <tmark@isc.org> - Status changed from 'new' to 'review'

# Tue, 22 Aug 2017 11:09:25 -0400 Thomas Markwalder <tmark@isc.org> - Untaken

# Thu, 31 Aug 2017 10:20:31 -0400 Francis Dupont <Francis_Dupont@isc.org> - Taken

# Fri, 01 Sep 2017 09:00:27 -0400 Francis Dupont <Francis_Dupont@isc.org> - Given to Thomas Markwalder <tmark@isc.org>

# Wed, 06 Sep 2017 10:27:53 -0400 Thomas Markwalder <tmark@isc.org> - Version Fixed 4.4.0 added

# Wed, 06 Sep 2017 10:27:53 -0400 Thomas Markwalder <tmark@isc.org> - Dependency by #24720: added

# Wed, 06 Sep 2017 10:54:41 -0400 Thomas Markwalder <tmark@isc.org> - Correspondence added [Reply] [Comment]

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Hello Tim: You'll be pleased to hear that we've addressed your issue in our next release of ISC DHCP, 4.4.0, which is due out first quarter 2018. As you reported, the server would return a client's previously released prefix lease even when the client subsequently provided a prefix length hint that did not match that lease. Now the server will only return the previous lease if it exactly matches the hint or the prefix-length-mode is set to "ignore". Otherwise, it will attempt to allocate a new prefix based on the hint and the prefix-length-mode. We like to recognize contributors by citing them in our release notes. If you wish to be thanked in this manner please respond with how you want to be identified. Most often it is by name and/or organization. Thanks for taking the time to report this issue. Regards, Thomas Markwalder ISC Software Engineering

# Wed, 06 Sep 2017 10:54:42 -0400 Thomas Markwalder <tmark@isc.org> - Status changed from 'review' to 'resolved'

# Wed, 06 Sep 2017 11:33:31 -0400 Tim DeNike <tim@denike.us> - Correspondence added [Reply] [Comment]

Date:	Wed, 6 Sep 2017 11:33:22 -0400
To:	dhcp-public@isc.org
Subject:	Re: [ISC-Bugs #45780] Fwd: DHCPv6 PD oddity with client changing prefix size.
From:	"Tim DeNike" <tim@denike.us>

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Sure thing. Tim DeNike - Lightspeed Communications Thanks! Sent from my iPhone > On Sep 6, 2017, at 10:54 AM, Thomas Markwalder via RT <dhcp-public@isc.org> wrote: > > Hello Tim: > > You'll be pleased to hear that we've addressed your issue in our next release of ISC DHCP, 4.4.0, which is due out first quarter 2018. > > As you reported, the server would return a client's previously released prefix lease even when the client subsequently provided a prefix length hint that did not match that lease. Now the server will only return the previous lease if it exactly matches the hint or the prefix-length-mode is set to "ignore". Otherwise, it will attempt to allocate a new prefix based on the hint and the prefix-length-mode. > > We like to recognize contributors by citing them in our release notes. If you wish to be thanked in this manner please respond with how you want to be identified. Most often it is by name and/or organization. > > Thanks for taking the time to report this issue. > > Regards, > > Thomas Markwalder > ISC Software Engineering > >

# Wed, 06 Sep 2017 11:33:33 -0400 The RT System itself - Status changed from 'resolved' to 'open'

# Tue, 10 Oct 2017 15:29:04 -0400 Thomas Markwalder <tmark@isc.org> - Status changed from 'open' to 'resolved'

Bug #45780 for dhcp-public: Fwd: DHCPv6 PD oddity with client changing prefix size.

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