Subject: [6lo] #15 (routing-dispatch): current entry as reference for next entry compression in RH

From: "6lo issue tracker" <[email-masked]>
Date: Tue, 26 Jan 2016 17:53:07 -0000

#15: current entry as reference for next entry compression in RH

 From: Tengfei Chang [mailto:[email-masked]]
 Sent: mardi 26 janvier 2016 18:10
 To: Pascal Thubert (pthubert) <[email-masked]>
 Cc: [email-masked]; [email-masked]
 Subject: Re: [6lo] Compression Reference and Coalescence

 Yes, Pascal. What you are going to say is correct!

 I agree +1

 Tengfei

 On Tue, Jan 26, 2016 at 6:06 PM, Pascal Thubert (pthubert)
 <[email-masked]> wrote:
 I see, and yes, that is misleading.

 I need to change that to say the reference to the first is the source of
 the packet and then the reference for each entry is the previous one when
 uncompressed (not the first as you suggest but, the one just before it).
 So you uncompress an address and it becomes reference to the next that you
 uncompress, etc… I will raise an ticket. . You’ll find that the algorithm
 in “5.4.  Popping Headers” decodes exactly that (well hopefully).

 Do we agree?

 Pascal

 From: Tengfei Chang [mailto:[email-masked]]
 Sent: mardi 26 janvier 2016 17:56
 To: Pascal Thubert (pthubert) <[email-masked]>
 Cc: [email-masked]; [email-masked]
 Subject: Re: [6lo] Compression Reference and Coalescence

 Nice to hear that's what you intended to do!

 In  the beginning of section 4.3:
 ...

    Once the address of the source of the packet is determined, it
    becomes the reference for the compression of the addresses that are
    located in compressed RH3 headers that are present inside the IP-in-
    IP encapsulation in the uncompressed form.
 ...

 When I am understanding the sentence, I am feeling like all the
 compression of addresses in RH3 will be compressed according to source
 address in IPinIP, which only the first 8 bytes can be elided.

 If agree with the reasonable one, it should be the first address in first
 RH3 is compressed according to the source address in IPinIP.
 Then, all rest address in RH3 will be compressed according to the first
 address in RH3.

 Make sense?
 Tengfei

 On Tue, Jan 26, 2016 at 5:23 PM, Pascal Thubert (pthubert)
 <[email-masked]> wrote:
 Hello Tengfei:

 The draft is meant to express exactly what your reasonable case shows.
 There is an example of that in appendix.
 What exactly did I write improperly that it can be understood otherwise?

 Take care ;

 Pascal

 From: 6lo [mailto:[email-masked]] On Behalf Of Tengfei Chang
 Sent: lundi 25 janvier 2016 12:00
 To: [email-masked]; [email-masked]
 Subject: [6lo] Compression Reference and Coalescence

 Dear all,

 I have some concern on the compression Reference and Coalescence.

 In the 6lorh draft, all the hops in RH3 are compressed according to the
 compression reference (the source address, root usually). And when doing
 Coalescence, the process is kind of like taking the first address in first
 RH3 as the reference. The inconsistency between compression reference and
 Coalescense may waste some bytes in some cases.

 For example:
 A packet is issued by root with a compressed RH3 along an A->B->C->D
 source route path.

 The nodes address are:
 root:      bbbb::0000:0000:0000:0001
 node A: bbbb::1111:2222:3333:0001
 node B: bbbb::1111:2222:3333:0002
 node C: bbbb::1111:2222:3333:0003
 node D: bbbb::1111:2222:3333:0004

 According to the 6lorh draft: all hops in RH3 will be compressed according
 to reference, which is the root. The  Packet received by node A is:
 ----------------------------
 Type 3 RH3-6LoRH Size = 2  1111 2222 3333 0001
                                            1111 2222 3333 0002
                                            1111 2222 3333 0003

 And which maybe more reasonable packet would be like :
 ----------------------------
 Type 3 RH3-6LoRH Size = 0  1111 2222 3333 0001
 Type 0 RH3-6LoRH Size = 1  02
                                             03
 Which means the first hop in first RH3 entry is compressed according to
 the reference(which is the root in this case) and the rest hops are
 compressed according to the first hop in first RH3 entry. For me, this
 compression way is more consistent  with the way when doing coalescence.

 What do you think?
 Tengfei

-- 
-------------------------+-------------------------------------------------
 Reporter:               |      Owner:  draft-ietf-6lo-routing-
  [email-masked]     |  [email-masked]
     Type:  defect       |     Status:  new
 Priority:  major        |  Milestone:
Component:  routing-     |    Version:
  dispatch               |   Keywords:
 Severity:  Active WG    |
  Document               |
-------------------------+-------------------------------------------------

Ticket URL: <https://trac.tools.ietf.org/wg/6lo/trac/ticket/15>
6lo <https://tools.ietf.org/6lo/>

---

From: "6lo issue tracker" <[email-masked]>
Date: Tue, 26 Jan 2016 17:53:28 -0000

Changes (by [email-masked]):

 * owner:  [email-masked] => [email-masked]
 * status:  new => assigned

-- 
--------------------------------+---------------------------------
 Reporter:  [email-masked]  |       Owner:  [email-masked]
     Type:  defect              |      Status:  assigned
 Priority:  major               |   Milestone:
Component:  routing-dispatch    |     Version:
 Severity:  Active WG Document  |  Resolution:
 Keywords:                      |
--------------------------------+---------------------------------

Ticket URL: <https://trac.tools.ietf.org/wg/6lo/trac/ticket/15#comment:1>
6lo <https://tools.ietf.org/6lo/>