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

["Spagnolo, Phillip A" <phillip.a.spagnolo at boeing.com>]

Acee,

Thanks for presenting these results.  Your data and method will allow
for some healthy discussion and comparison.

See some initial comments and questions below.

> -----Original Message-----
> From: Acee Lindem [mailto:acee at cisco.com] 
> Sent: Friday, November 04, 2005 12:53 PM
> To: ospf-wireless-design at ietf.org
> Subject: [Ospf-wireless-design] OSPF Flooding and Higher Mobility
> 
> 
> 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.

Are you allowing any adjacent path or are you limiting the adjacent path
to a certain length?

> 
> 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.

LSA caching is not exclusive to MPRs.  In order to get a fair
comparison, it should be run independently.  The strategy will work in
either method.  Can you provide results excluding the LSA caching or
using with both methods?

> 
> For MDRs we used the standard bi-connected topology.
> 
> We will provide the diffs for the code changes supporting 
> smart peering.

Can you provide the scripts you used to generate these results?  I would
like to validate your MDR results before working with MPRs.  My first
check did not match exactly, but I don't trust it because I don't know
the parameters you used.

> 
> 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.

Can you explain this comment more clearly?

Lastly, I looked at the 50 node data for MPRs and MDRs.  Why do the MPRs
have so many LSA that are out of sync between the databases?  I was
wondering if LSA caching was covering something up here?

Thanks,
Phil


> 
> Stan Ratliff, a Cisco Software Engineer, will be presenting 
> these results.
> 
> Thanks and Sorry for the Short Notice,
> Acee
> 
> 

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