Subject: [v6ops] DHCPv6 PD client on cellular on some IoT platform

From: Alexandre Petrescu <[email-masked]>
Date: Wed, 24 May 2017 19:05:49 +0200

Hello,

We discussed extensively about the potential use of DHCPv6 Prefix 
Delegation on cellular links.

The chicken issue is the lack of DHCPv6 PD software on typical User 
Equipment.  For example, there is no DHCPv6-PD app on Android.  The egg 
issue is the lack of operator support of DHCPv6-PD towards the User 
Terminal.  For example, there is no cellular operator answering to 
DHCPv6-PD requests issued by the User Terminal.

To address the chicken issue, we started with an ISC DHCP open software 
client, which does implement Prefix Delegation.  It can be 
(cross)compiled on various platforms; then type "./dhclient -6 -P"; this 
sends an DHCPv6 Solicit Identity Associtaion for Prefix Delegation 
message on the interface.

However, whereas this software runs ok on interfaces such as Ethernet, 
USBnet and WiFi interfaces, it breaks if run on the cellular interface 
of some IoT cellular platform.  The error can be corrected by the 
quick-and-dirty solution below.

Alex

------------------------------------------------------------------------
The error says "//UNSUPPORTED DEVICE TYPE 503 FOR RMNET0."
dhcp-4.3.5
./common/lpf.c
line number: 551

//default:
//      log_fatal("Unsupported device type %ld for \"%s\"",
//                (long int)sa->sa_family, name);
   default:
         hw->hlen = 7;
         hw->hbuf[0] = HTYPE_ETHER;
         memcpy(&hw->hbuf[1], sa->sa_data, 6);
   break;

(two programmers worked this out).

Alex

---

From: Tomek Mrugalski <[email-masked]>
Date: Wed, 24 May 2017 20:03:28 +0200

> quick-and-dirty solution below.
Alex,

Thanks for bringing this issue up and for using ISC software. Personally
I think v6ops (and any other WG mailing list) is not an appropriate
place for discussing topics specific to a given implementation, but I'll
leave that determination for the chairs.

Can I ask you to repost your report to dhcp-users, a list dedicated to
users of ISC DHCP software? It's available at
https://lists.isc.org/mailman/listinfo/dhcp-users

Once you do that, I'll respond there explaining how to improve your
patch, as it has a couple flaws that require improvements.

Thanks,
Tomek Mrugalski
ISC

---

From: "Templin, Fred L" <[email-masked]>
Date: Wed, 24 May 2017 21:21:31 +0000

Hi Alex,

We have been doing DHCPv6 PD on Androids for a long time. DHCPv6 messaging
is via a tunnel over the cellular and WiFi links. The DHCPv6 client app was easy to
implement and requires just a small amount of code and a few DHCPv6 messages.
The DHCPv6 server we are using is from ISC.

Thanks - Fred

> -----Original Message-----
> From: v6ops [mailto:[email-masked]] On Behalf Of Alexandre Petrescu
> Sent: Wednesday, May 24, 2017 10:06 AM
> To: [email-masked]
> Subject: [v6ops] DHCPv6 PD client on cellular on some IoT platform
> 
> Hello,
> 
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