Re: [RRG] RRG shouldn't try to directly address mobility, including qualifying mobility attributes

[Brian E Carpenter <brian.e.carpenter@gmail.com>]

I too suggest *not* boiling this particular part of the
ocean. If we don't have a viable fixed network, mobility
will become moot anyway. First things first, for all the
reasons Eric gives.

    Brian

On 2008-03-20 10:10, Fleischman, Eric wrote:
> Team-mates:
> 
> I've been grappling with mobility affects upon routing systems for much
> of this decade. I am not optimistic that this group will be able to
> directly address mobility in a manner that will result in an RRG
> consensus. I also do not believe that this group is likely to be able to
> qualify mobility attributes such as "granularity and churn" in a
> satisfying manner. Rather, the following is the view from my knothole:
> 
> 1) The semantics of mobility differs in different contexts. In my own
> research, I have found it helpful to distinguish between geographical
> mobility (i.e., the affects of one node moving relative to another,
> which can also include the signal intermittence affects caused by
> attenuation (distance) or signal blockages due to landforms, foliage,
> buildings, particulate matter (dust storms), the weather, or the pitch,
> roll, or yaw of the moving node impacting its own antenna's signal
> propagation or reception) and organizational mobility (i.e., moving a
> computer from one vehicle to another, moving part of an organization
> into another part of an organization).
> 
> 2) Different systems interpret geographical movement as being "mobility"
> very differently. For example, for certain satellite systems, an entity
> can move hundreds of miles and not leave the satellite's beam. From the
> perspective of that satellite, that entity has not moved (i.e., no
> mobility has occurred). By contrast, stationary nodes may exhibit
> "mobility" given certain weather or particulate matter environments
> (e.g., as a function of frequency ranges).
> 
> 3) Routing protocols confuse underlying signal intermittence with
> mobility. The impact of signal intermittence varies in terms of which
> part of the protocol stack is being focused on. The higher one goes up
> the protocol stack, the longer the duration the signal intermittence
> event can be before the protocol must address it. One can take steps to
> dampen these affects, but ultimately signal intermittence events will be
> noted if their duration is long enough.
> 
> 4) Mobility affects are a partial function of the network architecture.
> Architectures similar to 3GPP, for example, naturally view mobility from
> a mobile IP (MIP) perspective. By contrast, I have primarily been
> working in MANET environments and those environments view similar
> mobility events quite differently. It is my personal belief that
> adherents of those two perspectives naturally interpret the same facts
> differently -- and certainly various mobility attributes have very
> different routing implications to each orientation.  
> 
> 5) Ran Atkinson's posting on February 21st focused on a technical report
> that for entities moving every few minutes or less, the protocol system
> works better if mobility is handled at L2 than L3. Because I largely
> agree with this conclusion, I mention Ran's posting here as another
> datapoint suggesting that this group can't (fully) consider mobility
> because L2 issues are out of RRG's scope. 
> 
> 6) A great deal of published research has been addressing various
> cross-layer protocol integration mechanisms for wireless systems over
> the past many years. I believe that the technical literature is
> concluding that cross-layer protocol integration techniques can
> significantly dampen mobility affects upon IP routing protocols.
> However, even if you agree with this conclusion, can RRG presume that
> such techniques will be implemented in a consistent manner? I think not
> (for the foreseeable future) ... thereby making the creation of a
> consensus position for this group all the more difficult because we will
> be talking apples and oranges -- and to what purpose?
> 
> 7) I believe that the research community has already formed a consensus
> that in wireless environments network performance and scaling is
> enhanced if the network's topology is hierarchical. Of all of my
> observations, I believe that this is the only useful observation that is
> suitable for the RRG to use in order to create a consensus position.
> 
> Therefore, I believe that if RRG is to address mobility, it is because
> the selected RRG approach is so clean that it incidentally also enhances
> mobility (i.e., mobility is a secondary affect for RRG and not a gating
> requirement).
> 
> --Eric
>  
> 
> -----Original Message-----
> From: William Herrin [mailto:bill@herrin.us] 
> 
> On Thu, Mar 13, 2008 at 6:18 PM, Tony Li <tony.li@tony.li> wrote:
>>  Or, in other words, we should drop the mobility discussion for now, 
>> deal  with the granularity and churn issues, and then see if we are 
>> happy with the  bounds that that imposes on mobility.
> 
> Hi Tony,
> 
> Do we have a consensus on what target numbers for granularity and churn
> could support mobility directly in the routing system? If not, I submit
> that we should continue our tangent long enough to get them.
> 
> While we might or might not want to support mobility directly in the
> routing architecture, it would be very informative if we could say:
> yes, this proposal meets the target criteria for mobility in the routing
> architecture and no, that proposal does not.
> 
> Regards,
> Bill Herrin
> 
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