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

Ole, are you talking about the amnesiac client case - such as, the client reboots
and then comes back to life again with no memory of its past lifetime? Our
lease lifetimes are short - generally about 30 seconds - so any stale leases
should be very transient. But, our relays also retain knowledge about the
client<->server interactions and in some sense act as a proxy for the client.
So, the relay itself will clean up after an amnesiac client when it detects
that the client has suffered a traumatic event.

Fred

> -----Original Message-----
> From: otroan@employees.org [mailto:otroan@employees.org]
> Sent: Wednesday, October 07, 2020 6:55 AM
> To: Templin (US), Fred L <Fred.L.Templin@boeing.com>
> Cc: ianfarrer@gmx.com; v6ops list <v6ops@ietf.org>; 6man WG <ipv6@ietf.org>; dhcwg <dhcwg@ietf.org>
> Subject: Re: [dhcwg] [EXTERNAL] 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
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> 
> > On 7 Oct 2020, at 15:50, Templin (US), Fred L <Fred.L.Templin@boeing.com> wrote:
> >
> > We implement DHCPv6 PD on relays. The relay is always co-resident with the
> > delegating server and behaves according to RFC6221. Are we covered?
> 
> What's your experience with implementing section 3.5 / R-4?
> 
> Cheers,
> Ole
> 
> >
> > Thanks - Fred
> >
> > From: dhcwg [mailto:dhcwg-bounces@ietf.org] On Behalf Of ianfarrer@gmx.com
> > Sent: Wednesday, October 07, 2020 3:26 AM
> > To: v6ops list <v6ops@ietf.org>; ipv6@ietf.org
> > Cc: dhcwg <dhcwg@ietf.org>
> > Subject: [EXTERNAL] [dhcwg] 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.
> >
> >
> > Hi,
> >
> > We are currently finishing WGLC for this draft. It describes requirements for a 'DHCPv6 Delegating Relay' - this is a router functioning
> as the L3 edge and DHCPv6 relay (only) with prefix delegation. This is a common deployment scenario, but RFC3633/8415 only really
> describes PD using a Delegating Router - i.e the L3 edge also functions as a DHCPv6 server with no relay. When the relay and server
> functions are performed by separate devices a number of problems with how relays behave have
> > been observed, so this document addresses them.
> >
> > During WGLC for this, Ole raised a comment related to one of the routing requirements:
> >
> > R-4:    If the relay has learned a route for a delegated prefix via a
> >            given interface, and receives traffic on this interface with
> >            a destination address within the delegated prefix (that is
> >            not an on-link prefix for the relay), then it MUST be
> >            dropped.  This is to prevent routing loops.  An ICMPv6 Type
> >            1, Code 6 (Destination Unreachable, reject route to
> >            destination) error message MAY be sent back to the client.
> >            The ICMP policy SHOULD be configurable.
> >
> > The problem that this is trying to solve is:
> >
> > 3.5.  Forwarding Loops between Client and Relay
> >
> >    If the client loses information about a prefix that it is delegated
> >    while the lease entry and associated route is still active in the
> >    delegating relay, then the relay will forward traffic to the client
> >    which the client will return to the relay (which is the client's
> >    default gateway (learnt via an RA).  The loop will continue until
> >    either the client is successfully reprovisioned via DHCP, or the lease
> >    ages out in the relay.
> >
> > Ole’s comment: "And I would also be happy if we could have some implementors chime in with a "we are happy and able to
> implement this requirement”.”
> >
> >
> > We would appreciate any feedback on this, especially from anyone with experience implementing DHCPv6 relays with PD.
> >
> >
> > Thanks,
> > Ian
> >
> >
> > Current draft version: https://datatracker.ietf.org/doc/draft-ietf-dhc-dhcpv6-pd-relay-requirements/
> >
> >
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