Re: [trill] WG Last Call: draft-ietf-trill-directory-framework-01.txt

Linda Dunbar <linda.dunbar@huawei.com> Tue, 27 November 2012 16:11 UTC

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From: Linda Dunbar <linda.dunbar@huawei.com>
To: "Black, David" <david.black@emc.com>, "trill@ietf.org" <trill@ietf.org>
Thread-Topic: [trill] WG Last Call: draft-ietf-trill-directory-framework-01.txt
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Date: Tue, 27 Nov 2012 16:11:11 +0000
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Subject: Re: [trill] WG Last Call: draft-ietf-trill-directory-framework-01.txt
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David, 

Thank you very much for the detailed comments. I will incorporate them in the next revision. 

Some answers to your comments are inserted below:


> -----Original Message-----
> From: Black, David [mailto:david.black@emc.com]
> Sent: Saturday, November 24, 2012 2:29 PM
> To: trill@ietf.org; Linda Dunbar
> Subject: RE: [trill] WG Last Call: draft-ietf-trill-directory-
> framework-01.txt
> 
> Hi Linda,
> 
> Here are some (somewhat tardy) comments on this WG Last Call.
> 
> (1) As noted by some of the others who commented, more functionality
> details would be good to add, especially on mixing of the push and
> pull models in Section 5.  Cache consistency needs to be covered,
> at least its invalidation portion, as relying solely on aging out
> entries can black-hole traffic that uses a stale entry that hasn't
> aged out yet.
> 
[Linda] This framework is mainly to cover the benefits of directory service. I will add some high level description, however I will try not to repeat the description in the mechanism draft which covers the details of caching and policy of pull/push. 

> (2) I also agree with Erik's earlier comment about not understanding
> why Appointed Forwarders are in this draft.  If use of a directory
> can relax Appointed Forwarder restrictions without causing problems
> (e.g., loops), that needs to be explained somewhere, probably in
> Section 4.  Otherwise, Appointed Forwarders should not be discussed.
[Linda] Agree. Will change accordingly. 

> 
> (3) On the comment about capitalizing MUST, SHOULD and MAY, the
> applicable RFC is RFC 2119, but those terms are not ordinarily used
> in requirements documents.  An explanation that these keywords
> express requirements on protocol development should be provided in
> order to use the upper case versions of these keywords.
> 
[Linda] Will change per you comments. Thanks. 

> Here are some more detailed comments:
> 
> Abstract:
>    Edge RBridges currently learn the mapping between MAC addresses and
>    their egress RBridges by observing the data packets traversed
>    through.
> 
> Change to: ... by observing traffic that traverses the RBridge.
> 
> Section 1, 1st paragraph:
> 
>                 (This ''blocked'' state
>    has no effect of TRILL Data or IS-IS frames, which can still be sent
>    and received. It only affects native frames.)
> 
> "of TRILL data" -> "on TRILL Data" in second line above.
> 
> In item 2 in the list, I'd change "usually" to "often":
>    2. Topology is usually based on racks and rows.
> 
> In item 3 in the list, explain that server reload can change the MAC
> address and why that change may be needed or desirable, because
> Section 4 appears to assert that the MAC address can change.  If
> that wasn't intended, this text in Section 4 needs attention for
> physical servers (it's ok for VMs):
> 
>    When a VM is moved to a new
>    location or a server is loaded with a new application with different
>    IP/MAC addresses, it is more likely that the DA of data packets sent
>    out from those VMs are unknown to their attached edge RBridges.
> 
> Item 4 should follow up on the mention of subnets in item 3 and
> observe that multiple subnets on the same port at the same time is
> common for server virtualization and the change rate is higher than
> for physical servers.
> 
> In the definition of "Bridge", change "draft" to "document".
> 
> Section 3, p.6, first bullet - change both instances of "RB1" to
> "an RBridge" as there's no RB1 in figure 1.
> 
> The last bullet in Section 3.1 is a bit sloppy about its use of the
> word "entries".  It needs to explain exactly what is in an "entry" -
> it might be possible to do this in an introduction by stating that
> the presence of an entry (and list what it contains) avoids flooding
> of inbound frames that match the entry.
> 
> Section 3.2, Scenario #1 - The use of the word "uplink" is confusing,
> overly constraining and not necessary.  The important concept is how
> many ToR switches are in each rack.  It's quite feasible for a server
> or switch in a rack to have multiple uplinks to the same ToR (e.g.,
> when the links are 1 Gigabit Ethernet).
> 
> Section 4, first sentence:
> OLD
>    In data center environment, applications placement to servers,
>    racks, and rows is orchestrated by Server (or VM) Management
>    System(s).
> NEW
>    In a data center environment, the assignment of applications
>    to servers, including rack and row selection, is orchestrated
>    by Server (or VM) Management System(s).
> END
> 
> I'd suggest deleting Section 6 (Conclusion and Recommendations),
> as it's important for considering what the WG will do, but may not
> have much value in a published RFC.
> 
> 
> Thanks,
> --David
> 
> > -----Original Message-----
> > From: trill-bounces@ietf.org [mailto:trill-bounces@ietf.org] On
> Behalf Of Erik
> > Nordmark
> > Sent: Wednesday, November 14, 2012 4:13 PM
> > To: trill@ietf.org
> > Subject: Re: [trill] WG Last Call: draft-ietf-trill-directory-
> framework-01.txt
> >
> >
> > We would really like to she some more explicit indications from WG
> > participants that they have read this document and agree with it.
> >
> > Please include any substantial as well as editorial improvements that
> > result from reviewing the document.
> >
> >     Erik
> >
> > On 10/25/12 3:55 PM, Donald Eastlake wrote:
> > > This message begins a TRILL WG two week Last Call on the
> > > draft-ietf-trill-directory-framework draft.
> > >
> > > Thanks,
> > > Donald
> > > =============================
> > >   Donald E. Eastlake 3rd   +1-508-333-2270 (cell)
> > >   155 Beaver Street, Milford, MA 01757 USA
> > >   d3e3e3@gmail.com
> > > _______________________________________________
> > > trill mailing list
> > > trill@ietf.org
> > > https://www.ietf.org/mailman/listinfo/trill
> > >
> >
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