Re: [dtn-users] LTP Convergence Layer - Help needed!

[Nik Ansell <[e-mail]>]

Hello All,

After a break, I have restarted testing and noticed some strange behaviour
from LTPlib.
It will send one bundle, but then fail to send any further bundles.

After some investigation using wireshark, it appears to pick a random
source port, so when the receiving node sends an acknowledgement back, it
sends it to the source port, which fails to arrive because the sending node
is not listening on that port.
Does anyone have any idea how I can workaround this problem?
Interface and link statements from the config files are below.

I have tried without the local_port statements, but without this nothing
works. I have also tried with and without the ion_mode=true statements with
no success.
I have also attempted to add a udp interface, but this does not seem to
work either.

tx:
interface add ltp0 ltp local_addr=$shorthostname ion_mode=true
link add link_ltp_rx2node rx:1113 ALWAYSON ltp local_port=1113
remote_port=1113 mtu=1400 ion_mode=true

rx:
interface add ltp0 ltp local_addr=$shorthostname ion_mode=true
link add link_ltp_tx2node tx:1113 ALWAYSON ltp local_port=1113
remote_port=1113 mtu=1400 ion_mode=true

Any help will be very gratefully received!!

Kind Regards,
Nik

On Thu, Dec 3, 2015 at 10:39 PM, Zoller, David A. (MSFC-EO50)[HOSC SERVICES
CONTRACT] <[e-mail]> wrote:

> Hi Nik,
>
> It has been a good while since I worked with the LTPLib and I never tried
> a setup like your node2, but, your configs look reasonable to me.
>
> I suggest getting the second 2 node setup from “2 to 3” (assuming you did
> the “1 to 2” connection) working standalone and then combine the #2 configs.
>
> --
>
> You can try removing the local port from the links – I think by default
> the LTPLib uses a dynamic port for each session and specifying it might
> interfere.
>
>
>
> You also might try setting the option   ion_mode=true  on both the
> interface and link add statements to see if that changes the behavior. That
> kind of negates the dynamic port usage.
>
> Best regards,
>
> DZ
>
>
>
> *From:* Nik Ansell [mailto:[e-mail]]
> *Sent:* Thursday, December 03, 2015 12:08 PM
> *To:* Zoller, David A. (MSFC-EO50)[HOSC SERVICES CONTRACT]
> *Cc:* [e-mail]
> *Subject:* Re: [dtn-users] LTP Convergence Layer - Help needed!
>
>
>
> Hi David,
>
>
>
> Thank you for your kind reply, you are 100% correct.
>
> The very helpful "Interface list" command told me that it was indeed
> listening on port 1113.  So I updated my config files to use port 1113 but
> it still didn't work.
>
>
>
> I did however manage to get a 2 node setup working using port 1113, as per
> my previous update.
>
>
>
> Do you know of any else I can do to troubleshoot the 3node setup?
>
>
>
>
> Kind Regards,
> Nik
>
>
>
> On Thu, Dec 3, 2015 at 10:04 PM, Zoller, David A. (MSFC-EO50)[HOSC
> SERVICES CONTRACT] <[e-mail]> wrote:
>
> Hi Nik,
>
> interface add ltp0 ltp local_addr=$shorthostname is probably listening on
> port 1113 by default and your LTP links are transmitting to port 4556.
>
> I recommend changing the LTP links to use the IANA assigned port 1113.
> (The UDP interface is listening on 4556 by default).
>
> Hope that gets you going,
>
> DZ
>
>
>
>
>
> *From:* dtn-users [mailto:[e-mail]] *On Behalf Of *Nik
> Ansell
> *Sent:* Thursday, December 03, 2015 11:23 AM
> *To:* [e-mail]
> *Subject:* [dtn-users] LTP Convergence Layer - Help needed!
>
>
>
> Hi,
>
>
>
> I have successfully setup a 3 node UDPCL and TCPCL topology and am able to
> send bundles OK.
>
>
>
> Next I installed LTPLib and rebuilt DTN2, ensuring that ./configure found
> the location of LTPlib OK.
>
>
>
> I have updates the config files to use ltp, but for some reason no bundles
> seem to be sent or queued!
>
>
>
> If anyone could shed any light on a possible problem I will be forever in
> their debt, as bundles just seem to disappear!
>
>
>
> My testing so far has been starting dtnd on all 3 nodes, then running the
> dtnsend command twice to send 2 test bundles from node 1 to node 3.
>
> "dtnsend -s dtn://tx.dtn/a -d dtn://rx.dtn/g -t m -p "hello""
>
>
>
> I run dtnrecv on node 3:
>
> "dtnrecv dtn://rx.dtn/g -q -o F#####.bin"
>
>
>
> "bundle list" on nodes 1,2&3" returns zero bundles, so none are in the
> queue.
>
> "bundle stats" on node 1 returns:
>
> Bundle Statistics: 0 pending -- 0 custody -- -- bpq --  bpq -- 2 received
> -- 0 delivered -- 0 generated -- 2 transmitted -- 0 expired -- 0 duplicate
> -- 2 deleted -- 0 injected
>
> "link dump link_ltp1" on node 1 returns:
>
> Current link:
>
> Link link_ltp1:
>
> clayer: ltp
>
> type: ALWAYSON
>
> state: OPEN
>
> deleted: false
>
> nexthop: mx:4556
>
> remote eid: dtn:none
>
> mtu: 1400
>
> min_retry_interval: 5
>
> max_retry_interval: 600
>
> idle_close_time: 0
>
> potential_downtime: 30
>
> prevhop_hdr: false
>
> reincarnated: true
>
> used in fwdlog: true
>
>             local_addr: 255.255.255.255 local_port: 4556
>
>             remote_addr: 10.0.0.2 remote_port: 4556
>
>             mtu: 1400
>
>             Red/Green balance: all red
>
>             ION mode: false
>
>
>
> Config files:
>
>
>
> Node1
>
> interface add udp0 udp
>
> interface add ltp0 ltp local_addr=$shorthostname
>
>
>
> #          Create link to MX
>
> link add link_ltp1 mx:4556 ALWAYSON ltp mtu=1400 local_port=4556
> remote_port=4556 remote_addr=10.0.0.2
>
>
>
> #          Add route to RX via MX
>
> route add dtn://rx.dtn/* link_ltp1
>
>
>
> Node2:
>
> interface add udp0 udp
>
> interface add ltp0 ltp local_addr=$shorthostname
>
>
>
> #          Create link to TX
>
> link add link_ltp2 tx:4556 ALWAYSON ltp local_port=4556 remote_port=4556
> mtu=1400 remote_addr=10.0.0.1
>
>
>
> #          Create link to RX
>
> link add link_ltp3 rx:4556 ALWAYSON ltp local_port=4556 remote_port=4556
> mtu=140 remote_addr=10.0.0.3
>
>
>
> #          Add route to TX
>
> route add dtn://tx.dtn/* link_ltp2
>
>
>
> #          Add route to RX
>
> route add dtn://rx.dtn/* link_ltp3
>
>
>
> Node3:
>
> interface add udp0 udp
>
> interface add ltp0 ltp local_addr=$shorthostname
>
>
>
> #          Create link to MK
>
> link add link_ltp1 mx:4556 ALWAYSON ltp local_port=4556 remote_port=4556
> remote_addr=10.0.0.2
>
>
>
> #          Add route to TX via MX
>
> route add dtn://tx.dtn/* link_ltp1
>
>
>
> Kind Regards,
> Nik
>
>
>