Re: [ns] Why the message is not delivered (ARP requests lost?)

[Chalermek Intanagonwiwat <intanago@ISI.EDU>]

No. 802.11 doesn't guarantee that all messages will be successfully
delivered. So, if the messages are rarely lost, nothing is
wrong with that. But, yes, the control message is very important. An
ack for a control message would definitely help.

-- Chalermek

On Fri, 14 Sep 2001, YY YY wrote:

> The message are lost in low frequency. I noticed that in some case the 
> interest messages are also lost. It is only because the interest message is 
> forwarded by all nodes, so all source nodes can receive it in high 
> probability. But in one of my experiment, one source is far away from the 
> sink and has only one neighbor. Unfortunately, the interest message 
> forwarded by its only neighbor is lost, so the source node does not start to 
> send packets at all. I am not sure why these messages are dropped. Is it 
> because of the MAC layer? Can 802.11 guarantee that all messages sent out 
> are finally delivered with only  some delay, if the queue is long
enough? If 
> not, does this mean I have to send an ack for those control messages, 
> because they are very important.
> 
> thanks for your help
> 
> Yong
> 
> 
> 
> >From: Chalermek Intanagonwiwat <intanago@ISI.EDU>
> >To: YY YY <yy_yaoyong@hotmail.com>
> >CC: ns-users@ISI.EDU
> >Subject: Re: [ns] Why the message is not delivered (ARP requests lost?)
> >Date: Fri, 14 Sep 2001 10:24:55 -0700 (PDT)
> >
> >Does this happen in every round of positive reinforcement ?
> >
> >-- Chalermek
> >
> >On Fri, 14 Sep 2001, YY YY wrote:
> >
> > > Hi, there:
> > >
> > > I am using ns2 to simulate the ad hoc network and the routing protocol 
> >is
> > > directed diffusion. The scenario is simple enough with only three nodes, 
> >one
> > > sink and three sources(one node has both a sink and a source). When two
> > > nodes unicast positive reinforcement messages to the third one
> > > simultaneously, only one message is delivered. I checked the trace file 
> >and
> > > found that both nodes sended an ARP request first, but only one is 
> >received
> > > by the destination. So only one ARP reply message is generated. The 
> >network
> > > is far from overload and the lost positive message is critical to the
> > > protocol. I don't understand why only the ARP Requests are dropped. Is 
> >it
> > > because of confict? But all data messages are delivered successfully.
> > >
> > > Thanks a lot.
> > >
> > > Yong
> > >
> > >
> > > Node 1 sends Pos to 0; (Generate ARP request)
> > > Node 2 sends Pos to 0; (Generate ARP request)
> > >
> > > 0 receivs 1's request and replies;
> > > 0 doesn't receive the ARP request from 2;
> > >
> > > r 0.117095713 _2_ AGT  --- 16 diffusion 36 [0 0 0 0] [energy 
> >9999.994047]
> > > ------- [2:255 2:0 32 0]
> > > s 0.117150647 _1_ MAC  --- 0 ARP 80 [0 ffffffff 1 806] [energy 
> >9999.994017]
> > > ------- [REQUEST 1/1 0/0]
> > > s 0.117150713 _2_ MAC  --- 0 ARP 80 [0 ffffffff 2 806] [energy 
> >9999.994047]
> > > ------- [REQUEST 2/2 0/0]
> > > r 0.117470668 _0_ MAC  --- 0 ARP 28 [0 ffffffff 1 806] [energy 
> >9999.994070]
> > > ------- [REQUEST 1/1 0/0]
> > > s 0.118329800 _0_ MAC  --- 0 MAC 44 [28f 1 0 0] [energy 9999.994070]
> > > r 0.118505821 _1_ MAC  --- 0 MAC 44 [28f 1 0 0] [energy 9999.993703]
> > > s 0.118515821 _1_ MAC  --- 0 MAC 38 [1ed 0 0 0] [energy 9999.993703]
> > > r 0.118667841 _0_ MAC  --- 0 MAC 38 [1ed 0 0 0] [energy 9999.993863]
> > > s 0.118717841 _0_ MAC  --- 0 ARP 80 [a2 1 0 806] [energy 9999.993863]
> > > ------- [REPLY 0/0 1/1]
> > > r 0.119037862 _1_ MAC  --- 0 ARP 28 [a2 1 0 806] [energy 9999.993475]
> > > ------- [REPLY 0/0 1/1]
> > > s 0.119047862 _1_ MAC  --- 0 MAC 38 [0 0 0 0] [energy 9999.993475]
> > > r 0.119199883 _0_ MAC  --- 0 MAC 38 [0 0 0 0] [energy 9999.993590]
> > >
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