Re: I never thought of this scenario

Lawrence D'Oliveiro <ldo@nz.invalid> wrote:

On Fri, 19 Apr 2024 07:23:27 +0200, Marc Haber wrote:
 

Lawrence D'Oliveiro <ldo@nz.invalid> wrote:
>

On Sun, 14 Apr 2024 20:13:58 -0500, Grant Taylor wrote:
>

The DHCP agent is needed ...
And DHCP is routable ...

>
Routable protocols get through routers without the help of special
“agents”.

 
The unicast part¹ of DHCP gets through a router just fine without agent.

 
Get through to what? What is there on the other side of a router, that
didn’t need to be involved in the rest of the exchange?
 

¹ which is about 80 % of the protocol

 
Ah, I see now: you are all really talking about this “80% DHCP” or
“discount DHCP” or “20%-off DHCP”, aren’t you. While the rest of us were
talking about “proper DHCP” or “fully-implemented DHCP” or “DHCP according
to the spec”.

We are talking about the *full* spec, you, however, are only talking
about the initial IP allocation.  There's much more to DHCP than just
initial IP address allocations.

And, the protocol "must" be routable:

RFC2131: https://www.rfc-editor.org/rfc/rfc2131 - page 6:

        DHCP should not require a server on each subnet.  To allow for
        scale and economy, DHCP must work across routers or through the
        intervention of BOOTP relay agents.

Note they use "must" above in the statement "DHCP must work across
routers".  Page 4 defines "must" as:

        o "MUST"
       
        This word or the adjective "REQUIRED" means that the item is an
        absolute requirement of this specification.

Therefore the RFC explicitly allows for DHCP to be routed.