Re: [dhcwg] [EXTERNAL] Re: [v6ops] Re: Question to DHCPv6 Relay Implementors regarding draft-ietf-dhc-dhcpv6-pd-relay-requirements

"Templin (US), Fred L" <Fred.L.Templin@boeing.com> Fri, 16 October 2020 20:49 UTC

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From: "Templin (US), Fred L" <Fred.L.Templin@boeing.com>
To: "otroan@employees.org" <otroan@employees.org>
CC: Vasilenko Eduard <vasilenko.eduard@huawei.com>, Michael Richardson <mcr+ietf@sandelman.ca>, v6ops list <v6ops@ietf.org>, 6man WG <ipv6@ietf.org>, dhcwg <dhcwg@ietf.org>
Thread-Topic: [EXTERNAL] Re: [dhcwg] [v6ops] Re: Question to DHCPv6 Relay Implementors regarding draft-ietf-dhc-dhcpv6-pd-relay-requirements
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Date: Fri, 16 Oct 2020 20:48:59 +0000
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Subject: Re: [dhcwg] [EXTERNAL] Re: [v6ops] Re: Question to DHCPv6 Relay Implementors regarding draft-ietf-dhc-dhcpv6-pd-relay-requirements
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Ole,

> The CPE requirements document could have had a requirement that it should never forward a packet received on the WAN interface
> back out the WAN interface.

That is what I said before, but I qualified it by saying "should never forward a packet
received on the WAN interface back out the WAN interface *via a default route*."
It could be that there are more-specific routes that would cause a packet coming
into the WAN interface to go back out the WAN interface and that is OK; but, not
via a default route.

However, the further discussion seems to suggest that the delegating router needs
to be mindful of clients that maliciously or otherwise send ping-ponged self-directed
packets. I was worried that the delegating router would not be able to distinguish
CPE router A from CPE routers B, C, D in some cases. But, I am not worried about
that anymore.

Thanks - Fred

> -----Original Message-----
> From: otroan@employees.org [mailto:otroan@employees.org]
> Sent: Friday, October 16, 2020 11:31 AM
> To: Templin (US), Fred L <Fred.L.Templin@boeing.com>
> Cc: Vasilenko Eduard <vasilenko.eduard@huawei.com>om>; Michael Richardson <mcr+ietf@sandelman.ca>ca>; v6ops list <v6ops@ietf.org>rg>;
> 6man WG <ipv6@ietf.org>rg>; dhcwg <dhcwg@ietf.org>
> Subject: [EXTERNAL] Re: [dhcwg] [v6ops] Re: Question to DHCPv6 Relay Implementors regarding draft-ietf-dhc-dhcpv6-pd-relay-
> requirements
> 
> This message was sent from outside of Boeing. Please do not click links or open attachments unless you recognize the sender and
> know that the content is safe.
> 
> 
> >
> > We are talking past each other, and one of us does not have a clear understanding
> > of the issue at the heart of the discussion which I see as a forwarding plane issue
> > having nothing to do with the control plane.
> 
> Well, the forwarding plane just does what it's told.
> When you set up DHCP with static routes at both ends, which are maintained by snooping on a protocol. It's not inconceivable that
> there are cases where you'd get a routing loop. Good thing we have the HLIM field. ;-)
> 
> Markus' draft is still the most authorative document discussion the solution space:
> https://tools.ietf.org/html/draft-stenberg-v6ops-pd-route-maintenance-00
> 
> The CPE requirements document could have had a requirement that it should never forward a packet received on the WAN interface
> back out the WAN interface.
> 
> Cheers,
> Ole=