Re: [RTG-DIR] Rtgdir early review of draft-ietf-rtgwg-routing-timer-param-sync-00

Michael Richardson <mcr+ietf@sandelman.ca> Tue, 16 January 2018 20:02 UTC

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From: Michael Richardson <mcr+ietf@sandelman.ca>
To: Stewart Bryant <stewart.bryant@gmail.com>
cc: rtg-dir@ietf.org, draft-ietf-rtgwg-routing-timer-param-sync.all@ietf.org, ietf@ietf.org, rtgwg@ietf.org
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Subject: Re: [RTG-DIR] Rtgdir early review of draft-ietf-rtgwg-routing-timer-param-sync-00
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Stewart Bryant <stewart.bryant@gmail.com> wrote:
    >> 3) please give the Timer Param Sync protocol a clear name. Not crazy
    >> about that name.

    > It is a protocol to synchronize the value of timers. I suppose we could
    > call it "Timer value synchronization protocol". Note it synchronizes
    > the value of the timer so that a common timeout is used across the
    > network rather than synchronizing the protocols. Would the WG prefer
    > coordination to synchronization?

I have particular opinion, but coordination does seem like a better term.

    >> Followup comments:
    >>
    >> * While the document tried to describe the Timer Parameter
    >> functionality seperate from the first use of the parameter
    >> (fast-reroute), it failed to tell me anything about the new protocol
    >> other than bits on the wire.  I would like the ISIS/OSPF diagrams to
    >> more cleary refer subtype to the new "Routing Timer Parameter
    >> Synchronization Registry".

    > I am not sure I understand your concern here. Are you concerned with
    > the general definition (which follows the tradition in the LS WGs) or
    > with the application?

I am concerned with the general definition. I found it abruptly short.

    >> I'm unclear what a router does when it sees one of these parameters in
    >> the flood.  Does it flood the same value?  How does it's preference
    >> value interact with the value presented?

    > This is link-state routing. Routers MUST flood link-state packets
    > unchanged, so they are unchanged.  To change a value would break a
    > protocol invariant of these routing protocols.  At the end of flooding
    > all routers can see the preference of all other routers and use this to
    > pick min/max/something else as specified by the application from the
    > set of values provided by the set of routers.

okay, but it's unclear in the document if a router that spoke ISIS on one
interface and OSPF on another would do something magic.  I think not, but
there is also discussion about devices flooding different values on different
interfaces... so maybe that's where I began to be confused.

    >> I would feel happier with two documents as well because then for each
    >> parameter being synchronized, the security considerations could more
    >> reasonably explain what unreasonable values are, and how to recognize
    >> silly values.  Security does not just defend against malicious actors,
    >> but also just mis-configured (fat-fingered) ones.

    > Again, up to the Chairs, I can easily split if that is what the WG
    > wants, but would hope we do not have to go all the way back to
    > individual submission.

Perhaps if there were seperate security considerations sections for the base
protocol, and then for the specific application which being proposed.

--
Michael Richardson <mcr+IETF@sandelman.ca>, Sandelman Software Works
 -= IPv6 IoT consulting =-