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

From: Acee Lindem <[email-masked]>
Date: Fri, 04 Nov 2005 15:52:40 -0500

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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From: Richard Ogier <[email-masked]>
Date: Fri, 04 Nov 2005 13:47:07 -0800

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).

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.

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:

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From: Acee Lindem <[email-masked]>
Date: Fri, 04 Nov 2005 17:08:05 -0500

> (unless you want to implement a biconnected version of Smart Peering).

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

> 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.