[Roll] Revisiting MPL Reconfiguration (Re: On Operation and Management of Large Scale MPL Network (Fwd: I-D Action: draft-doi-roll-mpl-nan-requirements-00.txt))

Yusuke DOI <yusuke.doi@toshiba.co.jp> Mon, 16 December 2013 02:49 UTC

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Date: Mon, 16 Dec 2013 11:49:13 +0900
From: Yusuke DOI <yusuke.doi@toshiba.co.jp>
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Subject: [Roll] Revisiting MPL Reconfiguration (Re: On Operation and Management of Large Scale MPL Network (Fwd: I-D Action: draft-doi-roll-mpl-nan-requirements-00.txt))
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(2013-12-10 15:30), Yusuke DOI wrote:
> The issue I have is how to deploy a mesh network over even larger
> network, maybe up to 10,000 nodes, with very low application traffic.
> At the same time, we need communication channels for relatively-low
> latency (few seconds) broadcast for commanding and enough reliable
> broadcast file transfer. The draft
> draft-doi-roll-mpl-nan-requirements-00 introduces the requirement.
> For the objective, MPL seems to be the only choice for us. But it
> lacks some functionarities for operation and management. One of the
> spec we need is to configure and/or update MPL forwarder after
> deployment. My proposal for configuration and re-configuration is
> DHCPv6 option:
> http://tools.ietf.org/html/draft-doi-roll-mpl-parameter-configuration-03

Let me describe little bit more on this topic.

The following issues are what I need to solve.

1) MPL configuration and reconfiguration
  - New domains may appear after deployment
  - Existing domain configuration may be changed
  - Of course, it should be scalable
    (Peter suggested me to use SNMP, but we're going to scale out up to 10k)

2) Management I/F of MPL nodes, especially, seeds.
  - MIBs? Netconf? CoAP???
  - How many 'active transmitting data messages'? for rate control

I did preliminary analysis on MPL reconfiguration after ML discussion two-months ago, and now nearly-confident that the only problem is unbalanced transmission and almost no message will be lost just because of parameter update. Timers for running transmissions can be 'reset' as if there are some inconsistency detected, just after parameter update.

Here's list of parameters and expected effects after reset. Assumption is the forwarder is the only one with the updated parameter set:

  the forwarder is almost always have to send the first data messages

  the forwarder will not send the data message at the first interval

  the forwarder will continue to keep old data message and bitmap, if
  there are some transmission happend after neighbor's expiry and
  before the node's expiry, the forwarder may need to send old messages
  again (should not happen frequently)

  vice versa, the forwaeder may receive old messages.

IMIN, IMAX decreased or K increased:
  more chance to send messages

IMIN, IMAX increased or K decreased:
  less chance to send messages

  more messages to send. At the end of consistent intervals before
  expiration, the forwarder may be the only node to send the message

  less messages to send.

So, as far as I can recognize, parameter update is possible for implementations that can accept temporal unbalanced load of transmission. For battery-powered devices it may not be acceptable, but for power-supplied devices it should be acceptable as far as it does not harm the mesh network itself.



p.s. I'll be on winter vacation on later this week, and many of you weel be in holiday week when I'm back to office, so please accept longer latency on communication. Happy hollidays!