On 5/19/19 2:05 AM, Mikael Abrahamsson wrote:
There needs to be interaction between the packet forwarding layer and
the DHCP layer when doing things like DHCPv6-PD, otherwise it's not of
any use.
It was implicit to me, anyway, that this type of behavior is only
relevant when the DHCP-endpoint (customer) subnet default router's
control plane and the DHCP relay agent are in intimate communication
i.e. are essentially integrated in some meaningful way.
I guess you could extend the behavior to any situation where the router
is able to snoop the DHCP relay conversation, but I think that's fraught
with issues since, if the relay agent isn't on the router itself, who
knows where it is on the L2, and trying to snoop the relay-server
communication, rather than the client-relay exchange, may give lots of
crazy behavior.
If the relay isn't integrated with the router in any meaningful way, I
guess you have to fall back to some undefined "out of band signaling
protocol" which I guess we don't have, either. BGP or OpenFlow seem
like the most obvious options.
I guess most networks offering this are using heavy-weight subscriber
management facilities based on RADIUS or some other more-involved AAA
mechanism? That's obvious if you're running PPPoE and have highly
centralized L3 termination but less so if you're running native Ethernet
(or something that looks like Ethernet) everywhere with semi-distributed
L3 termination.
--
Brandon Martin
