Date: Mon, 9 May 2011 22:50:29 +0200 From: Luigi Rizzo <rizzo@iet.unipi.it> To: quamar niyaz <quamarniyaz.zhcet@gmail.com> Cc: freebsd-ipfw@freebsd.org Subject: Re: DummyNet configuration for opportunistic Links for emulating DTN Message-ID: <20110509205029.GC39097@onelab2.iet.unipi.it> In-Reply-To: <BANLkTinqPMv-Rf-iA9LBT7a2Y3U37AU9hA@mail.gmail.com> References: <BANLkTinqPMv-Rf-iA9LBT7a2Y3U37AU9hA@mail.gmail.com>
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On Mon, May 09, 2011 at 10:16:43PM +0530, quamar niyaz wrote: > Hi, > > I am working on a application which is meant for Delay Tolerant Network. I > want to emulate the opportunistic link availability for the data sending > nodes using dummyNet . One scenario, suppose from source node to > destination node let's say a data link is available at around 9 a.m. morning > and the latency of the link from source node to destination node is 1hr. So > if a request for upload comes around 8 a.m. at the sending node then the > data should start reaching to the destination node after 10 a.m. as the link > between the nodes comes at 9 and the latency is 1 hr so delivery time at the > destination node(9 a.m. +1hr. = 10.am.). In other words sending node should > hold the data in its buffer till 10 a.m as the nodes are actually in my 100 > Mbps LAN so for emulating this the sender must start sending the data after > 10 a.m. > > Can the buffer holds such large amount of data e.g. 500 MB for an hour. Or I > have to modify the buffer size if yes, to which file i have to modify and > then build dummynet. Or simply writing a batch scripts is fine for this. > Please let me know. Thanks in advance this kind of stuff belongs to the application layer, not in the link layer. It is not just a matter of buffering, but the fact that your application will likely want to choose what to send when the link becomes available. cheers luigi
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