Subject: [dtn-interest] How to disseminate unavailability information

From: [email-masked]
Date: Mon, 7 Nov 2011 17:31:14 +0900

Hi,

I am considering a situation when a node can not receive any bundle
due to lack of resources. Now, the node needs to disseminate this
unavailability information. Simplest way is: broadcast with 1 or 2 hop
distance limit. Is there any other effective way?

-SM

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From: "Ivancic, William D. (GRC-RHN0)" <[email-masked]>
Date: Mon, 7 Nov 2011 07:02:35 -0600

Bundling hops or convergence layer hops?

What is the concept of operations?  Would you even know how many hops away a DTN routing agent is?  That probably depends on the deployment environment.  Using Contact Graph Routing, one has to a priori, know the routing graph.  Using some type of opportunistic routing ... I'm not sure what you might do.  Also, I don't know if there is any standard method of telling a routing protocol what a nodes resources may be.  Although, that might be necessary, at least some type of scale.

- Will

On Nov 7, 2011, at 3:31 AM, <[email-masked]<mailto:[email-masked]>> wrote:

Hi,

-SM
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******************************
William D. Ivancic
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From: Zack Sims <[email-masked]>
Date: Mon, 7 Nov 2011 11:30:33 -0500

For bundles that have already been transmitted, the router's BP agent can
be configured to send custody transfer failed reports with the reason code
"depleted storage". However, this won't assist you with making forwarding
decisions that lessen custody failures. Even more, it is hop-by-hop (not
forward looking along a path) You would need a routing protocol that
considers storage availability and hop counts as route metrics. I'm not
aware of any DTN routing efforts that currently do this, though it is
possible that certain drafts are outdated or that I'm simply behind the
times. Most attempts seem to announce availability times rather than path
characteristics.

If one were to design a solution, it ought to consider use cases. For
example, high link latency or frequent, unpredictable disconnections could
lead to outdated routing information. In those cases, a probabilistic
approach might be the best option. In a scheduled environment, similar to
CGR, messages with values denoting 'predicted queue activity during
contact' and 'current queue availability' might suffice.

Best Regards,

-- 
*Zack Sims
Engineering Intern at NASA GRC
MTI Systems, Inc.
Graduate Assistant with IRG
Ohio University***

On Mon, Nov 7, 2011 at 8:02 AM, Ivancic, William D. (GRC-RHN0) <
[email-masked]> wrote:

> What is the concept of operations?  Would you even know how many hops away
> a DTN routing agent is?  That probably depends on the deployment
> environment.  Using Contact Graph Routing, one has to a priori, know the
> routing graph.  Using some type of opportunistic routing ... I'm not sure
> what you might do.  Also, I don't know if there is any standard method of
> telling a routing protocol what a nodes resources may be.  Although, that
> might be necessary, at least some type of scale.
>
> - Will
>
>
> On Nov 7, 2011, at 3:31 AM, <[email-masked]> wrote:
>
> Hi,
>
> [email-masked]
> [email-masked]