The problem is that the packets that you are sending to A3 have an incorrect
port address.
When you use
$ns connect $a1 $a2
then automatically all normal control packets sent by a1 have the
destination port of a2;
as a1 is not connected to a3 in TCL, you must set the port by hand in C++,
as NS will not do this for you, eg:
void myAgent::recv(Packet* p, Handler *h)
{
hdr_ip *iph = hdr_ip::access(p);
hdr_cmn *ch = hdr_cmn::access(p);
...
iph->saddr() = addr(); // (set my IP address)
iph->sport() = port(); // (set my source port)
iph->daddr() = nextHop_iaddr; // iaddr of n3
iph->dport() = nextHop_iaddr; // port of a3
regarding the iaddr comment: check
http://tagus.inesc-id.pt/~pestrela/ns2/ns2_haddr_tips.html
In my ns2_shared_procs.tcl "utils" tcl file, I introduce procs for all
possible conversions of each form, using the procs "handle2iaddr",
"handle2haddr", "handle2id", etc.
--------
you could also have debug this problem by:
- redefining the no-slot handler to invoke the run-time TCL
debugger;
- use the mash inspector to find exactly who are _o153, _o158, etc
(http://tagus.inesc-id.pt/~pestrela/ns2/ns2_debugging2.html)
If this helps you, please contribute the description of the problem and the
solution, in your own words, to the NS2 wiki.
Pedro Vale Estrela
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf
> Of Brad Montgomery
> Sent: segunda-feira, 3 de Julho de 2006 19:25
> To: ns-users@isi.edu
> Subject: Re: [ns] Multiple connections to a single agent
>
>
> I'm not sure I understand, and perhaps I've not adequately described what
> I'm trying to do, so I'll try again using a semi-hypothetical scenario:
> (Please keep in mind I'm new to ns!)
>
> Suppose I've got the following topology:
>
> N1 - N2 - N3
>
> And three "different" agents, (A1,A2,A3) which have all been implemented
> differently in C++. The basic idea is that I want these agents to
> automatically communicate with each other...
>
> In C++ I've written an A1::command() function that will 'send' sends an IP
> packet to the A2 agent. When the A2 agent receives this packet, it then
> sends a packet back to A1, which then gets returned to A2 (basically a 3-
> way
> handshake). A2 should then automatically send another packet to the A3
> agent by creating a packet, and inserting N3's address in the IP header.
> (I'm assuming all of my agents and nodes know about the topology)
>
> In TCL I've done this:
> ------------------------------------
> set n1 [$ns node]
> set n2 [$ns node]
> set n3 [$ns node]
>
> set a1 [new Agent/A1]
> set a2 [new Agent/A2]
> set a3 [new Agent/A3]
>
> $ns attach-agent $n1 $a1
> $ns attach-agent $n2 $a2
> $ns attach-agent $n3 $a3
>
> $ns connect $a1 $a2
> #$ns connect $a2 $a3 ;# if I do this, the handshake doesn't work
>
> $ns at 0.0 $a1 send
> ------------------------------------
>
> When I run this, ns gives me this error:
>
> --- Classfier::no-slot{} default handler (tcl/lib/ns-lib.tcl) ---
> _o158: no target for slot 3
> _o158 type: Classifier/Port
> content dump:
> classifier _o158
> 0 offset
> 0 shift
> 2147483647 mask
> 1 slots
> slot 0: _o153 (Agent/A3)
> ---------- Finished standard no-slot{} default handler ----------
>
>
> Basically I want A3 to look at any or all packets send to N3. How can I
> force this?
>
> I'm using ns-2.29 on Mac OS X 10.4.7.
>
> Thanks in advance!
>
> Brad
>
>
> On 7/2/06 6:10 PM, "Mark Shifrin" <[EMAIL PROTECTED]> wrote:
>
> > no problem with tcp
> > you can do attach agent as many time as you want to a single node.
> > you must first define it as tcp-source. and then to choose the
> application
> > which runs over this
> > tcp, for example i did it with FTP. moreover you can do it for n, within
> a
> > loop
> >
> > --- Brad Montgomery <[EMAIL PROTECTED]> wrote:
> >
> >>
> >> Hello All,
> >>
> >> I'm wondering if it's possible to have a single Agent connected to 2 or
> more
> >> other Agents. I have a topology similar to this:
> >>
> >> N2
> >> |
> >> N0 -- N1 -- N3 -- N4
> >>
> >> I have an agents A0, A2, A3 connected to N0, N2, N3 respectively, and I
> >> would like A0 to send a packet to A2, which would then in turn send a
> packet
> >> to A3. Is this possible?
> >>
> >>> From reading the mailing list archives, it seems like this may not be
> >> possible, so my second question would be this:
> >>
> >> Is it possible to attach an agent to a Node, and force that agent's
> recv
> >> function to get executed for every packet that passes through that
> node?
> >> For example: Could N2 send a packet to N4, so that A3's recv function
> >> processes that packet before sending it onward.
> >>
> >> Any help is GREATLY appreciated!
> >>
> >> Brad
> >>
> >>
> >
> >
> > enjoy the life -
> > Mark
> >
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