Android (lack of) support for DHCPv6

Wed Jun 10 14:27:23 UTC 2015

On Wed, 10 Jun 2015, George, Wes wrote:

>
> On 6/10/15, 9:13 AM, "Baldur Norddahl" <baldur.norddahl at gmail.com> wrote:
>
>> What standard exactly requires my router to be able to snoop a DHCP-PD to
>> create routes dynamically? That was left out and one solution is the one
>> we
>> use.
>
> WG] We use this in cable-land, so it's definitely documented in the DOCSIS
> standards. Not sure it exists anywhere in the IETF standards, and so YMMV
> on which platforms do and do not support it.

http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_dhcp/configuration/15-sy/dhcp-15-sy-book/ip6-dhcp-rel-agent.html#GUID-52D23F09-6829-4950-9431-92D9B7A255C0

"DHCPv6 Relay Agent Notification for Prefix Delegation

The DHCPv6 relay agent notification for prefix delegation allows the 
device working as a DHCPv6 relay agent to find prefix delegation options 
by reviewing the contents of a DHCPv6 RELAY-REPLY packet that is relayed 
by the relay agent to the client. When a prefix delegation option is found 
by the relay agent, the relay agent extracts the information about the 
prefix that is being delegated and inserts an IPv6 static route matching 
the prefix delegation information onto the relay agent. Future packets 
destined to that prefix via relay will be forwarded based on the 
information contained in the prefix delegation. The IPv6 static route is 
then left in the routing table until the prefix delegation lease time 
expires or the relay agent receives a release packet from the client 
releasing the prefix delegation."

I can't find IETF standards language apart from this:

"14.  Relay agent behavior

    A relay agent forwards messages containing Prefix Delegation options
    in the same way as described in section 20, "Relay Agent Behavior" of
    RFC 3315.

    If a delegating router communicates with a requesting router through
    a relay agent, the delegating router may need a protocol or other
    out-of-band communication to add routing information for delegated
    prefixes into the provider edge router."

>From what I can find, a lot of vendors seem to have functionality 
implemented to look at the relayed messages and install static routes 
without any OOO-communication.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se