[ipv6-wg] [Snac] [v6ops] "router cascade with DHCPv6-PD"

Ole Trøan <otroan at employees.org> wrote:
    >>>> The lack of a standardized way to communicate DHCPv6-server PD to
    >>>> DHCPv6-relay, and the expectation that the relay would just *snoop* =
    >>>> on the
    >>>> DHCPv6-PD contents has bugged me for a long time.  If we are going to
    >>>> recommend that they act as relays, then I'd like to fix that.

    >>> If DHCP is used for prefix assignment inside of a site, the relay does
    >>> not need to do route injection for the requesting router. The RR can
    >>> simply advertise the assigned prefix in routing.
    >>
    >> a) it's actually cross-site.

    > Elaborate please.

We have three entities.

1) the STUB router or other downstream "home" router.
2) the CPE router which is at the "north" side of the home LAN, and on the
   south side of the WAN/DSL/CMTS link.
3) The ISP DHCP server which is somewhere inside the ISP, with a DHCP
   relay at the BMS or Cable Head end to send to it.

If (2) treats a DHCP-PD request from (1) as a relay, then it would relay
to (3), which would allocate a new prefix.  That message would back through
(3) [where it gets snooped on, and maybe, yes, injected into the ISP routing system].

Then it would relayed to (2), which would then relay it to (1).
(2) has to do something to route the prefix to (1), which today, means
snooping on the results.  But, even if the (2) is operated by the ISP, it's
not part of the ISPs site.   The south side of (2) belongs to the home owner.
The prefix needs to be routed from (2) to (1).  There is no routing protocol
in the home at this time(alas!), so there is nothing to "inject" it into.



--
Michael Richardson <mcr+IETF at sandelman.ca>   . o O ( IPv6 IøT consulting )
           Sandelman Software Works Inc, Ottawa and Worldwide




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