Re: I never thought of this scenario

On 17.04.2024 um 03:17 Uhr Lawrence D'Oliveiro wrote:

No, I didn’t miss it at all. It’s listed under “design goals”, not
actually under how the spec works.
 
By definition such a protocol cannot work across routers, because
clients don’t know what routers are available until a DHCP server
tells them.

It can't work across routers without helpers because the client knows
nothing about the network, so the discover message will got to the
non-directed broadcast 255.255.255.255. Traffic to that address is by
design not being routed because that would mean forward it to the
entire world. Another problem is to get the answer back because the src
address is 0.0.0.0 at this stage. That is why the relay agent is needed
and forward all that with src and dst being unicast addresses.

Even with DHCPv6 a helper is needed if the DHCP server resides on
another link (also called broadcast domain).

--
kind regards
Marco

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