Re: [Roll] [roll] #85: which lifetime is for the end points (origin and target) vs. intermediate nodes.

[Mukul Goyal <[e-mail]>]

But, this would require DAG's life time to be set large enough to allow completion of DRO/DRO-ACK exchange. Intermediate routers would need to maintain state for temporary DAG longer than necessary and they might end up generating many unnecessary DIOs. So, how about if we require DRO/DRO-ACK exchange to be completed within twice the DAG lifetime duration? Intermediate routers would leave the DAG after its lifetime is over. The origin and target would remember this DAG for one more lifetime to allow DRO/DRO-ACK exchange to complete.

Thanks
Mukul 

----- Original Message -----
From: "Mukul Goyal" <[e-mail]>
To: "Pascal Thubert (pthubert)" <[e-mail]>
Cc: "roll" <[e-mail]>
Sent: Tuesday, April 10, 2012 7:55:07 AM
Subject: Re: [Roll] [roll] #85: which lifetime is for the end points (origin and target) vs. intermediate nodes.

OR the simpler option would be to require DRO/DRO-ACK exchange to complete within the DAG's life time? If we were to specify a new parameter for the time limit on DRO/DRO-ACK exchange, both target and origin would need to agree on the value of this parameter.

Mukul

----- Original Message -----
From: "Mukul Goyal" <[e-mail]>
To: "Pascal Thubert (pthubert)" <[e-mail]>
Cc: [e-mail], "roll" <[e-mail]>
Sent: Tuesday, April 10, 2012 7:50:16 AM
Subject: Re: [roll] #85: which lifetime is for the end points (origin and target) vs. intermediate nodes.

Hi Pascal

Hopefully we are talking about the same thing.

>No, it's not closed. We are talking about a contract between lower layers in all nodes including the source and origin to maintain necessary resources and all contracts must have a lifetime.

1. A node that joins a temporary P2P-RPL DAG maintains state for the DAG for the time duration specified as DAG life time.
2. A node that establishes hop-by-hop routing state for a route discovered using P2P-RPL maintains this state for the time duration specified in DODAG configuration option.

Origin and target need to exchange DROs and DRO-ACKs. I could specify a new configurable parameter to specify the time limit on this exchange. This parameter's value  has to be more than DAG life time. One option is to specify it in terms of existing parameters: DAG life time + (MAX_DRO_RETRANSMISSIONS + 1)*DRO_ACK_WAIT_TIME.

Thanks
Mukul
----- Original Message -----
From: "Pascal Thubert (pthubert)" <[e-mail]>
To: "Mukul Goyal" <[e-mail]>
Cc: [e-mail]
Sent: Tuesday, April 10, 2012 4:45:46 AM
Subject: RE: [roll] #85: which lifetime is for the end points (origin and target) vs. intermediate nodes.

Hi Mukul,

No, it's not closed. We are talking about a contract between lower layers in all nodes including the source and origin to maintain necessary resources and all contracts must have a lifetime.
I do not mind you overload the RPL lifetime of the routing for the states at origin and target and if you have a sentence that makes it clear then we'll be in agreement.

Cheers,

Pascal


-----Original Message-----
From: Mukul Goyal [mailto:[e-mail]] 
Sent: dimanche 8 avril 2012 17:52
To: Pascal Thubert (pthubert)
Cc: [e-mail]
Subject: Re: [roll] #85: which lifetime is for the end points (origin and target) vs. intermediate nodes.

Pascal

Can we consider this issue closed? Please see my last response.

Thanks
Mukul

----- Original Message -----
From: "roll issue tracker" <[e-mail]>
To: [e-mail], [e-mail]
Cc: [e-mail]
Sent: Wednesday, April 4, 2012 8:06:30 AM
Subject: [roll] #85: which lifetime is for the end points (origin and target) vs. intermediate nodes.

#85: which lifetime is for the end points (origin and target) vs. intermediate nodes.

 Problem (currently open)
 ------------------------------
 P2P creates temporary states in the transient DAG and less-but-still  temporary states in the endpoints. These are 2 different lifetimes. The  spec has 2 lifetimes, one in the config option and one in the RDO. The  spec is not sufficiently clear about which is which. In can appear to be  conflicting since the config option is supposed to apply to all routers  on the path. On the side, and in order to allow the reuse of instance  ID, the origin must be sure that all states for a previous usage of the  same value are gone. So we need a clear control / negotiation of the  lifetimes on the states that come with an instanceID. Again this is not  clear enough in the spec.



 [Pascal2]
 2) Same question if you want to create states at the target to route  back. How long does the target need to maintain the route? Who controls  that, the origin or the target? I'd expect to find a suggested lifetime  in the RDO with a confirmation in the DRO to let the target amend it.

 [Mukul2]
 If the target wants DRO-ACK it needs to maintain state until DRO-ACK is  received. Otherwise, the target needs to remember things until it is  done sending all the DROs. I will add the text to this effect.

 [Pascal3]
 If you are setting up a short term conversation, how long exactly is  that before the origin has to refresh the route? What controls clean up  in both sides? Usually you want a lifetime (see MIP6 for instance)

 [Mukul3]
 Is it that you are talking about the lifetime of the hop-by-hop routing  state? That is specified in the life time parameters in the DODAG  configuration option. The draft says that on page 9 while describing how  the DODAG configuration option should be set inside a P2P mode DIO:

 "The Default Lifetime and Lifetime Unit parameters in DODAG
      Configuration option indicate the life time of the state the
      routers maintain for a hop-by-hop route established using P2P-RPL
      and may be set as desired.
 "

 [Pascal4] Maybe that's so but then you need to reword a little bit cause  you got me qiute confused. I've been talking of the lifetime of the  states at origin and target for one conversation. Since they might be  having a transient conversation, and the origin might reuse the instance  ID soon, you need to give a limit in time to the states that you are  creating. Still that conversation is longer than the states in the  intermediate routers. So you have 2 lifetimes and you have to be very  clear which is which. Personally, I'd have used the lifetime in the  configuration option for all the routers on the way and I'd have used  the new lifetime in the RDO as the conversation lifetime in the end  points because:
 1)  that is the new concept.
 2) This would allow the target to confirm exactly how long it locks  resources,
 3) and this would be more compatible with the description of the config  option in RFC 6550.

 [Mukul4]
 There are two lifetimes:
 1) Lifetime of the temporary DAG: this is specified inside P2P-RDO
 2) Lifetime of the routing state for the hop-by-hop route established  using P2P-RPL: this is specified inside the DODAG configuration option.
 All routers on the established route (including the origin) maintain  state for this route for this much time. This time could very well be  infinity.

 Now, lets talk about the "states at origin and target". The origin and  the target maintain the state about the temporary DAG for the DAG's life  time. This is true for all the nodes that join this DAG. All such nodes  maintain state about the temporary DAG until the DAG's life time is  over. It is true that the target and the origin exchange DROs and  DRO-ACKs and this exchange could conceivably go on even after the  temporary DAG's demise. How long should the origin and target indulge in  this exchange (and hence remember the possibly dead DAG)? I think it is  purely their choice and the draft need not impose any artificial time  limit on this.

 Pascal

-- 
-----------------------------------+---------------------
 Reporter:  jpv@…                  |      Owner:  mukul@…
     Type:  defect                 |     Status:  new
 Priority:  major                  |  Milestone:
Component:  p2p-rpl                |    Version:
 Severity:  Submitted WG Document  |   Keywords:
-----------------------------------+---------------------

Ticket URL: <http://trac.tools.ietf.org/wg/roll/trac/ticket/85>
roll <http://tools.ietf.org/wg/roll/>

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