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Queuing a bundle for a transfer to the next-hop is only done if the
next-hop node is available as neighbor. Further, this process is
executed on several events. One such event is the generation of a
bundle, another is the availability of a neighbor.
In any cases routing in IBR-DTN is a reactive mechanism. There exists a
queue but this is limited to several bundles for each neighbor and a
FIFO without any ordering. If the queue is occupied, then no additional
bundle gets queued.
The retransmission mechanism handles the transmission back-off for each
re-queued bundle. While a bundle is in the re-queuing mechanism it is
still in the queue for the destination, but it is held back until the
back-off is past. Re-queuing might happen under several circumstances.
One of them is the failed connection to a neighbor which should be
available.
As told in some mails earlier, the priority is just an ordering in the
bundle storage. It is NO guarantee that bundles will be delivered in the
priority order. Further, you should not rely on bundle priorities for
hard constrains, since the DTN architecture (RFC4838) just defines them
as relative priorities which are limited to bundles of the same source
EID (and same destination EID).
An: Johannes Morgenroth <morgenroth@ibr.cs.tu-bs.de>
Betreff: Re: [ibr-dtn] Strange behavior sending bundles
Datum: Mon, 28 Jan 2013 16:21:19 +0100
What I do is to disable the wifi on the sender router and type the
dtnsend commands. After this I enable the wifi (so the sender router
sees the receiver router). By faking disconnection you mean this?
When a bundle is queued for transmission? Right after typing the dtnsend
command or when the sender router sees another node (or the destination
one)?
On the other hand, if a bundle is queued for transmission and the
transmission fails you should not try to retransmit the same bundle
again to maintain the sorted queue based in priority, instead of trying
to retransmit the next bundle? You will lost the sorting if you do in
this way.