Subject: RE: [AVT] RE: I-D ACTION:draft-ash-avt-hc-over-mpls-protocol-00.txt

From: "Ash, Gerald R \(Jerry\), ALABS" <[email-masked]>
Date: Mon, 23 May 2005 07:57:55 -0500

Colin,

Thanks very much for your comments, please see responses below.

Jerry

> The definition of terms and reference to RFC 2119 needs to be moved  
> within the body of the text, rather than being a separate unnumbered  
> section. I'd suggest placing the paragraph at the start of Section 2.
> 
> Section 1, 2nd paragraph: "the compressed packet routed on an MPLS  
> LSP using MPLS labels" --> "the compressed packet _is_then_ routed..."
> 
> Section 2, 1st paragraph: I found the phrasing about pseudowires  
> transporting the "HC context and other control messages" a little  
> confusing, implying that the context and control messages are  
> transported separately to the compressed data packets. It might be  
> clearer to say "MPLS pseudowires (PWs) are used to transport the  
> header compressed packets between the ingress and egress...".
> 
> Section 2, 3rd paragraph: The sentence "Compressed packets and HC  
> control packets are routed on a separate MPLS LSP/PW..." could be  
> interpreted as a requirement to setup two PWs, one for the HC  
> compressed data packets and one for the HC control packets. It might  
> be clearer to state "Compressed data is routed on a separated MPLS  
> LSP/PW from compressor to decompressor"?
> 
> Section 2.1, top of page 7: I agree that there is no problem with  
> duplicate CIDs since they're received on separate sessions. However,  
> the text can be read to imply that something other than normal CID  
> processing is required. This confusion comes from the statement  
> following ("...the HD can distinguish these this it knows the 
> source by  means of the PW label"), which implies that there is a
> single HD for all PWs. It would be clearer if the draft made it
> explicit that each PW had a logically separate HD instance,
> independent of all other PWs.

Agree with all of the above comments/suggestions; will change
accordingly.

> Section 2.1, last paragraph: in order to assign a new PW type, the  
> IANA must be given explicit guidance on what to assign. This 
> requires a statement much like those in section 2.1 of the
> pwe3-iana-allocation draft, listing a numeric type to assign along
> with a description for that type.

This can be clarified by changing Section 6 'IANA Considerations' in the
draft to read:
 
"As discussed in Section 2.1, a new PW type as defined in [IANA] needs
to be assigned as follows:
 
PW type      Description
0x00??       Header-compressed packets"

> Section 2.2: how are the reserved values to be allocated? The draft  
> needs to either define an allocation policy (and IANA registry) or  
> mandate that they MUST NOT be assigned.

You have a good point.  We can change the "RESERVED" codepoint labels to
"NOT USED", making it clearer that they're not reserved for future
assignment, but rather will never be used. 

_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www1.ietf.org/mailman/listinfo/avt

---

From: Colin Perkins <[email-masked]>
Date: Mon, 23 May 2005 14:03:49 +0100

Jerry,

[snip the points agreed]

On 23 May 2005, at 13:57, Ash, Gerald R ((Jerry)), ALABS wrote:
...
> 0x00??       Header-compressed packets"

This will be sufficient if you specify which PW type number is to be  
assigned. IANA won't do it themselves: the draft needs to specify the  
actual value.

> assignment, but rather will never be used.

It would be clearer if you could use normative language to state that  
the code points MUST NOT be used.

Colin