Re: [manet] ETT metrics draft

[Henning Rogge <[e-mail]>]

On 07/16/2013 11:29 PM, Ulrich Herberg wrote:
> Hi,
>
> I have also reviewed the draft. Since it's an early draft, just some
> high-level comments:
>    - I like the idea of specifying the ETT metrics and I hope you will
> issue a new revision.

We definitely will. Expect a new revision in the week after the IETF 
meeting.

>    - The introduction is a bit confusing. It talks about the Funkfeuer
> networks, and then suddenly jumps into details about ETT metric. I
> would suggest to focus the document on the metric itself, and
> mentioning the Funkfeuer networks only in the appendix.

Maybe a "history" appendix that explains where the ETX part of the 
metric comes from?

 > I also wonder
> why the intended status is informational? Shouldn't it be Experimental
> or Standards Track, since a protocol extension is specified?

Good question, I am not sure about this but I am open for advise.

>    - section 3 (Applicability); again, I would defocus on the Funkfeuer
> networks, just mention in general the use cases where the metric is
> useful. You should focus more on OLSRv2 itself, IMO.
>    - same section: "ETX metric that was used in the earlier [RFC3626]
> implementation". Note that RFC3626 only uses hop-count, so technically
> the olsr.org implementation was not RFC3626 compliant

Yes.

>    - section 7: Since the link tuples are extended, does that mean that
> draft-ietf-manet-olsrv2 is "updated" (in the IETF sense)? If so, the
> draft does not say that in the header, nor mention that in the
> introduction and abstract.

I wrote the link tuple extension as a way to have "link specific" data 
stored for the metric. Do you think it would be better to put this into 
a database described in this draft?

 > I assume that an informational document
> could also not do that.
>   - "L_ETT_last_pkt_seqno  is the last received packet sequence number
> received from this link." Shouldn't there some section somewhere to
> describe requirements, such as access to lower layers (e.g., packet
> sequence numbers)?

I don't consider packet sequence numbers as a different layer. Its a 
different interface to the rfc5444 (de)multiplexer, but its still in the 
same layer.

We use IP addresses from the IP header in NHDP/OLSRv2 without worrying 
about "lower layer access" too.

>   - section 9 mixes a bit the different layers (RFC5444 and RFC6130). I
> wonder if that could not be more separated.

Hmm.

>   - some lower case "must" in section 9; should that be 2119 or not?

Will have to look at this.

>   - section 13: Shouldn't that be a new link metric type allocation?
> How is the metric used in the OLSRv2 network?

Not sure if we want to allocate metric TLV extensions for specific 
metric types.

>   - why is OLSRv2 only an informative reference? Can there be normative
> references in an Informational document?

I thought only RFCs can be a normative reference, but my knowledge about 
rfc types and references types in them is a bit limited.

Henning Rogge

-- 
Diplom-Informatiker Henning Rogge , Fraunhofer-Institut für
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