Re: [Ospf-wireless-design] OSPF Flooding and Higher Mobility

[Acee Lindem <acee at cisco.com>]

Richard Ogier wrote:

> I'm sure other people will also comment, but I have some preliminary
> comments now. When comparing the overhead between Smart Peering
> and MDRs, you need to use uniconnected MDRs for a fair comparison
> (unless you want to implement a biconnected version of Smart Peering).

Possibly - this could explain why there is a slightly better delivery ratio

> Also, it would be nice to compare with 100 nodes, and to compare
> other measures than overhead, such as delivery ratio, etc.
> I am eager to see such results.

I haven't personally run any simulations but I've been told that the run
time increases significantly with the number of nodes. However, more
nodes would definitely be interesting - as well as, smaller pause times and
higher velocities.

> Another point to consider is that OSPF-MDR is a natural
> generalization of OSPF. (MDRs generalize DRs in a natural way.)
>
> Richard
>
>
> Acee Lindem wrote:
>
> > Based on the INRIA reports and attendant E-mail threads, we (Cisco) have
> > recently gone down the path of doing some simulations with higher 
> > mobility.
> > The attached spread sheets show the results for 16 m/sec velocity and
> > varying radio range. The pause time is still 40 seconds. We found the 
> > results
> > to be more drastic with a smaller pause time but had some problems 
> > getting
> > a complete set of runs.
> >
> > MPRs have the following improvements over the base provided with GTNetS:
> >
> >     - Smart Peering is fixed to avoid instability by running a second
> >       SPF to determine if a potential peer is available via a real
> >       adjacency or unsynchronized adjacency. The adjacency is only 
> > suppressed
> >       in the case of connectivity to the SPT via real adjacencies. This
> >       is discussed in the Boeing report but wasn't implemented.
> >
> > Also, we have enabled promiscuous LSA caching enabled with the LSA
> > cache timeout extended to 100 seconds. We are attempting to get some
> > runs with this disabled as well some with a shorter pause time.
> >
> > For MDRs we used the standard bi-connected topology.
> >
> > We will provide the diffs for the code changes supporting smart peering.
> >
> > We have also been investigating using the MDR strategy of reducing 
> > adjacencies
> > by taking advantage of the flooding topology. However, doing this 
> > effectively
> > is more complex than it first seemed.
> >
> > Stan Ratliff, a Cisco Software Engineer, will be presenting these 
> > results.
> >
> > Thanks and Sorry for the Short Notice,
> > Acee
> >
> >
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