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

"Templin (US), Fred L" <Fred.L.Templin@boeing.com> Wed, 14 October 2020 22:37 UTC

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From: "Templin (US), Fred L" <Fred.L.Templin@boeing.com>
To: Bob Hinden <bob.hinden@gmail.com>
CC: Michael Richardson <mcr+ietf@sandelman.ca>, dhcwg <dhcwg@ietf.org>, "IPv6 List" <ipv6@ietf.org>, v6ops list <v6ops@ietf.org>, "ianfarrer@gmx.com" <ianfarrer@gmx.com>, Ted Lemon <mellon@fugue.com>, Jen Linkova <furry13@gmail.com>
Thread-Topic: [EXTERNAL] [dhcwg] [v6ops] Re: Question to DHCPv6 Relay Implementors regarding draft-ietf-dhc-dhcpv6-pd-relay-requirements
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Date: Wed, 14 Oct 2020 22:37:25 +0000
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Subject: Re: [dhcwg] [EXTERNAL] [v6ops] Re: Question to DHCPv6 Relay Implementors regarding draft-ietf-dhc-dhcpv6-pd-relay-requirements
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> I note that the lack of “challenge” does not mean anyone agrees.   Agreement needs to be affirmative.

Fair enough, Bob; here is the assertion I made that I was referring to:

+ BTW, I am still waiting to hear how this concern is in any way specific to prefix
+ delegation, since it seems to be generic to any case of having a “stub” router
+ that maliciously attacks its own upstream link – no matter how that router
+ negotiates its prefixes with upstream network nodes.

Do the individuals CC'd on this list agree that this is a generic IPv6 issue and not
a DHCPv6-PD-specific issue?

Thanks - Fred

> -----Original Message-----
> From: Bob Hinden [mailto:bob.hinden@gmail.com]
> Sent: Wednesday, October 14, 2020 3:28 PM
> To: Templin (US), Fred L <Fred.L.Templin@boeing.com>
> Cc: Bob Hinden <bob.hinden@gmail.com>om>; Michael Richardson <mcr+ietf@sandelman.ca>ca>; dhcwg <dhcwg@ietf.org>rg>; IPv6 List
> <ipv6@ietf.org>rg>; v6ops list <v6ops@ietf.org>
> Subject: Re: [EXTERNAL] [dhcwg] [v6ops] Re: Question to DHCPv6 Relay Implementors regarding draft-ietf-dhc-dhcpv6-pd-relay-
> requirements
> 
> I note that the lack of “challenge” does not mean anyone agrees.   Agreement needs to be affirmative.
> 
> Bob
> 
> 
> > On Oct 14, 2020, at 3:24 PM, Templin (US), Fred L <Fred.L.Templin@boeing.com> wrote:
> >
> > Bob, several messages back it was established that the issue at the heart of this
> > discussion is not specific to DHCPv6 nor DHCPv6-PD. Instead, it is an issue that is
> > common to any situation where there are multiple "stub" IPv6 routers on a
> > downstream link from a "default" IPv6 router, no matter how the routing
> > information is established or maintained. So far, no one has challenged my
> > assertion that this is a generic (and not a DHCPv6-PD-specific) IPv6 issue and
> > I have been waiting to see if anyone wants to challenge that.
> >
> > Fred
> >
> >> -----Original Message-----
> >> From: Bob Hinden [mailto:bob.hinden@gmail.com]
> >> Sent: Wednesday, October 14, 2020 2:47 PM
> >> To: Templin (US), Fred L <Fred.L.Templin@boeing.com>
> >> Cc: Bob Hinden <bob.hinden@gmail.com>om>; Michael Richardson <mcr+ietf@sandelman.ca>ca>; dhcwg <dhcwg@ietf.org>rg>; IPv6 List
> >> <ipv6@ietf.org>rg>; v6ops list <v6ops@ietf.org>
> >> Subject: Re: [EXTERNAL] [dhcwg] [v6ops] Re: Question to DHCPv6 Relay Implementors regarding draft-ietf-dhc-dhcpv6-pd-relay-
> >> requirements
> >>
> >> With my chair hat on, is there a reason why this discussion is being copied to the 6MAN w.g.?   6MAN doesn’t maintain DHCP
> related
> >> items.
> >>
> >> Please remove ipv6@ietf.org from this thread.
> >>
> >> Bob
> >>
> >>
> >>> On Oct 14, 2020, at 12:19 PM, Templin (US), Fred L <Fred.L.Templin@boeing.com> wrote:
> >>>
> >>> Hi Michael,
> >>>
> >>>> -----Original Message-----
> >>>> From: Michael Richardson [mailto:mcr+ietf@sandelman.ca]
> >>>> Sent: Wednesday, October 14, 2020 11:58 AM
> >>>> To: Templin (US), Fred L <Fred.L.Templin@boeing.com>
> >>>> Cc: ianfarrer@gmx.com; Jen Linkova <furry13@gmail.com>om>; dhcwg <dhcwg@ietf.org>rg>; v6ops list <v6ops@ietf.org>rg>; 6man
> >>>> <ipv6@ietf.org>
> >>>> Subject: Re: [EXTERNAL] Re: [dhcwg] [v6ops] Re: Question to DHCPv6 Relay Implementors regarding draft-ietf-dhc-dhcpv6-pd-
> >> relay-
> >>>> requirements
> >>>>
> >>>>
> >>>> Templin (US), Fred L <Fred.L.Templin@boeing.com> wrote:
> >>>>> Michael, what I was referring to below as "failure" is the proxy case when
> >>>>> there is an L2 proxy P between the client and relay (e.g.,
> >>>>> RFC489). There
> >>>>
> >>>> RFC4389 describes an ND Proxy.
> >>>> Is that really an L2 proxy?
> >>>
> >>> Yes, I believe it is an L2 proxy.
> >>>
> >>>> It seems like it also must be contain either an L2-bridge, or must have the
> >>>> L3-routing table entries if it would really be capable of passing DHCPv6-PD
> >>>> prefixes through it.
> >>>
> >>> The only thing it has that includes L3 information is neighbor cache entries that
> >>> keep track of the client's actual L2 address on the downstream link segment,
> >>> but rewrites the client's L2 address to its own L2 address when forwarding
> >>> onto an upstream link segment. (In the reverse direction, it receives packets
> >>> destined to its own L2 address but the client's L3 address on the upstream
> >>> link segment, then rewrites the L2 address to the client's L2 address when
> >>> forwarding onto the downstream link segment.)
> >>>
> >>>> Can you explain how such a device would normally work for a client device
> >>>> A,B,C,D doing DHCPv6-PD through it?
> >>>
> >>> Sure. A sends a DHCPv6 Solicit using its IPv6 link-local address as the source,
> >>> and its L2 address as the link-layer source. The proxy converts the link-layer
> >>> source to its own L2 address when forwarding the DHCPv6 solicit onto the
> >>> upstream link. When the DHCPv6 Reply comes back, the IPv6 destination is
> >>> that of client A, but the link-layer destination is the L2 address of the proxy.
> >>> The proxy then converts the L2 destination to the address of client A and
> >>> forwards it on to the client.
> >>>
> >>>> And is the failure one where the router "R" fails to drop traffic it should,
> >>>> one where the router "R" drops traffic that it shouldn't?
> >>>
> >>> I was thinking more along the lines of the latter; if the only way that A has
> >>> for talking to B, C, D, etc. is by going through R, it wouldn't work if R was
> >>> unconditionally dropping everything.
> >>>
> >>> Thanks - Fred
> >>>
> >>>> --
> >>>> Michael Richardson <mcr+IETF@sandelman.ca>   . o O ( IPv6 IøT consulting )
> >>>>          Sandelman Software Works Inc, Ottawa and Worldwide
> >>>>
> >>>>
> >>>>
> >>>
> >>> --------------------------------------------------------------------
> >>> IETF IPv6 working group mailing list
> >>> ipv6@ietf.org
> >>> Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6
> >>> --------------------------------------------------------------------
> >