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Re: [manet] DYMO and other routing protocols
Charles E. Perkins wrote:
Hello folks,
I am quite hopeful that we can get to a converged routing protocol
that will subsume the best aspects of DYMO and OLSR.
I'm in the process of reading OLSRv2 spec for seeing it fitting MANEMO
topologies.
As an external, I must say that I would very much favor only one MANET
routing protocol and not two. It simply takes too much effort to just
read two documents (30+70 pages), not even mention the time it takes to
implement both protocols.
If possible, the length of a common protocol document should be upper
bounded, something like half the sum of parts.
Covergence is the only option now, IMHO, after all this time.
Alex
We have many recent results pointing the way forward, some of which I
presented at the last IETF. I am hoping to have a much more
complete presentation ready for the next meeting.
I think it is clear by now that proactive protocol operation is
better when either there is a strong requirement for minimizing
latency in an uncongested network, or when the traffic patterns are
not very sparse. So, for instance, if most nodes in an ad hoc
network have open communications with most other nodes in the same
network, the communication pattern is not at all sparse. The tricky
point is to find out how dense the traffic pattern needs to be in
order to favor proactive operation (or, alternatively, how sparse the
traffic has to be in order to favor reactive operation).
Furthermore, it is quite likely that some routes should be
proactively maintained even if route table entries are generally
acquired on demand. The canonical example is that nodes need a route
to a gateway [if one exists] (or default router) often enough that
the route should always be there. Whether this is done by periodic
advertisement or by triggered route repairs is a matter for further
study. One could imagine similar requirements might be imposed for
important servers in the network (e.g., certificate authority, data
sink, ...).
I do _not_ think that proactive protocols should automatically be the
choice for mesh backbone routers. Certainly not for all mesh
clients...! I would really question whether it is needed for all
other mesh points anyway. Plus, the whole concept gets quite fuzzy
if there are intermittent long-range connections to neighboring
meshes (as an example).
Regarding the naming of AODV vs. DYMO: this is a long story with as
much political as technical content, and for my own part the former
was by far the more persuasive factor to persuade me to agree to a
new name for the standards-track reactive protocol. Now the downside
is that we have exactly the confusion in evidence currently for
newly interested parties. Perhaps we should rename DYMO to be AODVv2
:-)
Finally, regarding:
I think each protocol and its supporters can easily make a case
where it will beat other protocols. Simply look at conference
publications for good examples.
Simply stated: caveat emptor.
Stated more verbosely and redundantly using more words and so on...
---> it is very important to fully understand the range of
applicability for each research result. These are sometimes not
stated very clearly. It is also very helpful, when possible, to
understand the motivations of the authors.
Regards, Charlie P.
ext Ian Chakeres wrote:
There is no winner takes all in the contest of routing protocols
for MANET. I think each protocol and its supporters can easily make
a case where it will beat other protocols. Simply look at
conference publications for good examples.
That said, we have chosen to standardize DYMO and OLSRv2 - one
reactive and one reactive protocol in the MANET WG. For more
information regarding when one might deploy one or the other,
please see the applicability statements in the drafts.
DYMO is a successor to AODV (and other reactive protocols). The
specification is chartered to become a proposed standard. AODV is
not being actively discussed or standardized in the WG.
Ian
On 6/6/07, David Murray <30179198 at student.murdoch.edu.au> wrote:
Hi,
I am wondering how DYMO fits in with the other routing protocols.
I have read a number of papers that discuss how on-demand
routing protocols like DSR/AODV work better in highly mobile
environments where movement is fast, CPU and memory are low and
batteries are limited. Equally, in situations where movement is
very low, and there are no power limitations, protocols like
OLSR/TBRPF/STAR perform better.
So, I have a mental picture of OLSR/TBRPF being predominantly
used in stationary 802.11 mesh devices and AODV/DYMO being used
to connect users mobile devices ush as phones and PDAs. Is this
correct or are things not quite as simple as this? (I know RFC
2501 discusses MANET applications and characteristics but the
discussion is quite general)
If this is correct, it seems to me that DYMO and AODV are used in
very similar situations (the ad hoc interconnect between users
devices). I am aware that DYMO is a simplified version of AODV
both in code and network operation. It seems like the major
difference is the path accumulation feature in DYMO which allows
nodes to append their information to a RREP to give other nodes
better knowledge of the topology. It also seems that the hello
feature has been removed in DYMO. So, is DYMO likely to be a
replacement for AODV or do they have different uses/applications?
Thanks for your time
Dave
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