Re: [Roll] [roll] #89: Spec is limited to single interface intermediate routers

[Mukul Goyal <[e-mail]>]

Hi Pascal,

I propose the following text to be placed inside the Applicability section:

"The participation in a P2P-RPL route discovery is currently limited to the routers with IPv6 addresses that are reachable in both incoming and outgoing directions, which it quite typical in usual LLN routers with a single radio"

Can we close this ticket?

Thanks
Mukul

----- Original Message -----
From: "roll issue tracker" <[e-mail]>
To: [e-mail], [e-mail]
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Sent: Wednesday, April 4, 2012 8:11:10 AM
Subject: [roll] #89: Spec is limited to single interface intermediate routers

#89: Spec is limited to single interface intermediate routers

 Problem (currently open)
 ------------------------------
 The spec does not allow for routers with multiple interfaces. It expects
 that an address is usable downwards and upwards.

 Discussion
 -------------

 [Pascal]
 "When an
 intermediate router adds itself to a route, it MUST ensure that the
 IPv6 address added to the route is reachable in both forward and
 backward directions."
 This is written with the vision that the router has a single interface
 and acts as a repeater.
 But really a router could have 2 interfaces on a same subnet in which
 case that clause does not fly.

 [Mukul]
 All I mean is that the accumulated route MUST NOT have an address that
 cannot be accessed in one of the directions. If the address cannot be
 accessed in the backward direction, then the DRO would not be able to
 travel to the origin.

 [Pascal2] Then you're preventing a router with 2 interfaces. That's sad.
 I'm fine for an experimental draft   but for standard track that will
 have to be changed.

 [Mukul2] OK, I am keeping it the way it is.

 [Pascal3] This also need to be logged as a last call issue and its
 proposed resolution. Nothing wrong with having limitations, yet I think
 we must have specific text to indicate that the spec so far is limited
 to devices with a single interface. When we make the Standard Track
 version, I expect we'll have to go beyond that limitation. The drawback
 is for experimental  implementations that may not be interoperable with
 the final solution.

 [Mukul3] Could you please explain how does the requirement regarding
 addresses to be accessible in both forward and backward directions
 limits P2P-RPL to only single interface devices? I think this
 requirement means that P2P-RPL cannot be used across link layers. Is
 that what you mean? I think allowing operation across link layers would
 require P2P-RDO to accumulate additional information (backward address
 to be used for forward addresses not accessible in backward direction).
 I think at the moment we want to avoid this complexity.

 [Pascal4] Because an IP address is associated to an interface. If you
 have 2 interfaces, even in a same subnet, there should be 2 addresses.

 [Mukul4] But, why would the two IP addresses the device has on the same
 subnet wont be accessible in both forward and backward directions?


 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/89>
roll <http://tools.ietf.org/wg/roll/>