Re: [v6ops] Updating RFC 7084

[Ted Lemon <[e-mail]>]

We’re writing a new specification here. We can say that the server is
required to support notification. But independent of that, the stub router
can see if the ra from the router that delegated a particular prefix
indicates that the router is no longer preferred.

Op ma 21 nov. 2022 om 12:30 schreef Vasilenko Eduard <
[e-mail]>

> How?
>
> The prefix has been delegated by the DHCP request from the stub router.
>
> Evidently, the stub router could not ping periodically for a refresh.
>
> Hence, the infrastructure router should “notify”.
>
> You said, “DHCP has notification”.
>
> I know that it is not used widely. Why?
>
> Would every built-in server support it?
>
> Eduard
>
> *From:* Ted Lemon [mailto:[e-mail]]
> *Sent:* Monday, November 21, 2022 8:26 PM
> *To:* Vasilenko Eduard <[e-mail]>
> *Cc:* IETF v6ops WG <[e-mail]>
> *Subject:* Re: [v6ops] Updating RFC 7084
>
>
>
> In this scenario the stub router knows the router is deprecated. Why would
> it not deprecate the prefix?
>
>
>
> Op ma 21 nov. 2022 om 12:23 schreef Vasilenko Eduard <
> [e-mail]>
>
> In-line
>
>
>
> *From:* Ted Lemon [mailto:[e-mail]]
> *Sent:* Monday, November 21, 2022 8:14 PM
> *To:* Vasilenko Eduard <[e-mail]>
> *Cc:* IETF v6ops WG <[e-mail]>
> *Subject:* Re: [v6ops] Updating RFC 7084
>
>
>
> You’ve described a situation, not a real world scenario. How did the host
> wind up in this situation?
>
> *[EV] his stub router just joined some infrastructure where connections to
> 2 carriers were available. Hence, the stub router received 2 prefixes and
> announced 2 PIOs to the host*
>
> Why is the network configured this way?
>
>
> *[EV] The person managing infrastructure would like resiliency. He has
> connected one router to 2 Carriers. Then received /56 prefixes from both.
> It is not MHMP – It is one router connected to different carriers.*
>
> Why is it that only by deprecating the prefix can the host experience
> reliable connectivity?
>
>
> *[EV] The host may use the PIO as the source address that is not connected
> anymore to the owner (Carrier). The different carrier would always do a
> uRPF check to drop the packet from the wrong source address (belonging to
> the different carrier).*
>
>
>
> Op ma 21 nov. 2022 om 12:11 schreef Vasilenko Eduard <
> [e-mail]>
>
> The host had many PIOs (from many PA prefixes).
>
> One prefix has become outdated somewhere upstream (because the connection
> to the carrier is lost), but the information has not been propagated to the
> host (DHCP is not the best for negative information propagation).
>
> The host may still try to use a dead PIO despite the same host having
> another alive PIO.
>
> The end user is unhappy, he could not open the site, and he calls you for
> help.
>
> Ed
>
> *From:* Ted Lemon [mailto:[e-mail]]
> *Sent:* Monday, November 21, 2022 8:04 PM
> *To:* Vasilenko Eduard <[e-mail]>
> *Cc:* IETF v6ops WG <[e-mail]>
> *Subject:* Re: [v6ops] Updating RFC 7084
>
>
>
> Try to give us an example of an actual user experience that would be
> affected by the behavior you are concerned about. Describe the network
> configuration.
>
>
>
> The reason I am skeptical of your concern is that I have no idea what real
> world scenario is motivating it.
>
>
>
> Op ma 21 nov. 2022 om 12:02 schreef Vasilenko Eduard <
> [e-mail]>
>
> Hi Ted,
>
> I do not want to ignore you.
>
> But I am not capable to explain it differently.
>
> It looks so obvious…
>
> Eduard
>
> *From:* Ted Lemon [mailto:[e-mail]]
> *Sent:* Monday, November 21, 2022 7:36 PM
> *To:* Vasilenko Eduard <[e-mail]>
> *Cc:* IETF v6ops WG <[e-mail]>; Ole Troan <otroan=
> [e-mail]>
> *Subject:* Re: [v6ops] Updating RFC 7084
>
>
>
> What’s the problem you’re trying to solve here?
>
>
>
> Op ma 21 nov. 2022 om 10:59 schreef Vasilenko Eduard <
> [e-mail]>
>
> It was not about routing.
>
> DHCP-PD propagates prefixes that would be used for PIOs.
>
> If Carrier is not available anymore, hosts should stop using these PIOs
> for source addresses.
>
> But the stub router should be informed that particular prefixes should not
> be used anymore.
>
> How?
>
> Then stub router could deprecate PIO (zero preferred lifetime).
>
> Ed/
>
> *From:* Ole Troan [mailto:otroan=[e-mail]]
> *Sent:* Monday, November 21, 2022 6:53 PM
> *To:* Vasilenko Eduard <[e-mail]>
> *Cc:* Ted Lemon <[e-mail]>; IETF v6ops WG <[e-mail]>
> *Subject:* Re: [v6ops] Updating RFC 7084
>
>
>
> Eduard,
>
>
>
> I think you confuse addressing with routing.
>
>
>
> O.
>
>
>
> On 21 Nov 2022, at 16:39, Vasilenko Eduard <
> vasilenko.eduard=[e-mail]> wrote:
>
> 
>
> Imagine that the uplink to the Carrier (DSL for example) is down.
>
> All hosts on the site should stop using the /48 prefix received from this
> carrier. It should happen preferably sub-second.
>
> How this negative information would propagate over the site? (multi-hop)
>
> Default PIO preferred time is 1 week. Fernando has the intention to change
> it to 2hours – still pretty bad.
>
> The resolution by the current ND is very bad.
>
> Eduard
>
> *From:* Ted Lemon [mailto:[e-mail] <[e-mail]>]
> *Sent:* Monday, November 21, 2022 6:30 PM
> *To:* Vasilenko Eduard <[e-mail]>
> *Cc:* IETF v6ops WG <[e-mail]>
> *Subject:* Re: [v6ops] Updating RFC 7084
>
>
>
> The DHCPv6 server could send a notification to the DHCPv6 client if we are
> concerned about this. But it’s not clear to me that we should be. If you
> think we should be, you need to actually make a case for that, not just
> assert that it’s so.
>
>
>
> Op ma 21 nov. 2022 om 08:52 schreef Vasilenko Eduard <vasilenko.eduard=
> [e-mail]>
>
> Hi all,
>
> I do not understand how DHCP-PD may be used for prefix distribution inside
> the site.
> Because uplink could go down.
> Should be some signaling to all routers on site that the prefix is not
> available anymore (and should be deprecated on all links).
> But DHCP is stateless in principle.
> This "flush renumbering problem" would be pretty difficult to fix.
> It would kill MHMP completely.
>
> Eduard
> -----Original Message-----
> From: v6ops <[e-mail]> On Behalf Of Brian E Carpenter
> Sent: Friday, November 18, 2022 9:02 PM
> To: Timothy Winters <[e-mail]>; IPv6 Operations <[e-mail]>
> Subject: Re: [v6ops] Updating RFC 7084
>
> On 19-Nov-22 03:47, Timothy Winters wrote:
> > Hello,
> >
> > I've started a draft to update RFC 7084 to support prefix delegation on
> the LAN interfaces.  The current state of IPv6 in home networks is ISP are
> assigning prefixes of appropriate sizes but they currently are under
> utilized due to the lack of prefix delegation on LAN interfaces.
> >
> > This draft is an attempt to add that support to the draft.
> >
> > https://datatracker.ietf.org/doc/draft-winters-v6ops-cpe-lan-pd/
> > <https://datatracker.ietf.org/doc/draft-winters-v6ops-cpe-lan-pd/>
> >
> > This is only an update to 7084 at the moment, there has been some
> discussion on the snac working group about leveraging this work as well.
> >
> > One item being discussed is this currently doesn't solve multi-homed
> networks.
>
> As a historical note, we've spent a lot of time in the past on
> multi-homing and more or less failed (and the HOMENET approach was designed
> for home nets, not for enterprises where the problem is probably more
> important).
>
> To summarise what I've said over on SNAC:
>
> 1. If we're going to mention PvDs in the 7084 update, I think we should
> also mention RFC 8028. It isn't that a CE router should necessarily support
> 8028, but that in a network that does implement 8028 on its subnet routers,
> the following part of 8028 applies:
>
> 2.2.  Expectations of Multihomed Networks
>
>     Networking equipment needs to support source/destination routing for
>     at least some of the routes in the Forwarding Information Base (FIB),
>     such as default egress routes differentiated by source prefix.
>     Installation of source/destination routes in the FIB might be
>     accomplished using static routes, Software-Defined Networking (SDN)
>     technologies, or dynamic routing protocols.
>
> Those egress routes of course lead to CE routers.
>
> (There is some other thinking about this topic in
> draft-vv-6man-nd-support-mhmp).
>
>     Brian
>
>
> >
> > I welcome any feedback about the proposal.
> >
> > ~Tim
> >
> > _______________________________________________
> > v6ops mailing list
> > [e-mail]
> > https://www.ietf.org/mailman/listinfo/v6ops
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