Implementation within TUN/TAP of the Priority Switching Scheduler (PSS)

June 4, 2026 ยท View on GitHub

Following A. Finzi, E. Lochin, A. Mifdaoui, F. Frances, Improving RFC5865 Core Network Scheduling with a Burst Limiting Shaper. IEEE Global Communications Conference (GLOBECOM), 4 December 2017 - 8 December 2017 (Singapore). Available https://hal.science/hal-04173550v1, if you use this code please cite this paper.

Copyright (C) 2018
Victor Perrier victor.perrier@student.isae-supaero.fr and Emmanuel Lochin emmanuel.lochin@isae-supaero.fr

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

2. Installation

Just type make. You can edit the Makefile and compile with the following options:

  • -DDEBUG to add debug messages concerning the sending and the receiving of TUN/TAP packets;
  • -DDUMP_STATS to dump the credit evolution vs time in a file;
  • -DDSCP to classify packets following a DSCP markng with EF: 1, AF: 2 else DF. The classification is done inside src/bls.c and src/pscheduler.c (seek for DSCP inside these files). Another option is to operate a classification on the packet port number (usefull if you do not wish to enable a DSCP marker). In that case compile without -DDSCP. By default, classification is done using destination port EF: 20000, AF: 20001 else DF. These values can be changed inside both files.

3. Usage

As soon as compiled, launch bin/pss -h for usage (see below):

./bin/pss -i <ifacename> [-s|-c <serverIP>] [-p <port>]
./bin/pss -h

-i <ifacename>: Name of interface to use (mandatory)
-s|-c <serverIP>: run in server mode (-s), or specify server address (-c <serverIP>) (mandatory)
-p <port>: port to listen on (if run in server mode) or to connect to (in client mode), default 30001
-h: prints this help text
-C: Capacity of the link in bit/s
-b: BW parameter for the AF class
-m: Lm parameter for the AF class
-r: Lr parameter for the AF class

4. Practical usecase with TUN/TAP

You first need to create a tun0 interface on the client:

sudo ip tuntap add mode tun dev tun0
sudo ip link set tun0 up
sudo ip addr add 192.168.10.1/24 dev tun0

Then same operation on the serveur side with a different IP adress for the tunnel interface:

sudo ip tuntap add mode tun dev tun0
sudo ip link set tun0 up
sudo ip addr add 192.168.10.2/24 dev tun0

First launch bin/pss -i tun0 -s on the server side and bin/pss -i tun0 -c W.X.Y.Z -C your_capacity_value -b your_bw_value -m your_Lm_value -r your_Lr_value on the client side to enable the tunnel with PSS where W.X.Y.Z is the server IP address (e.g. the IP address associated to eth0 for instance, not the tun0 IP address) .

5. Acknowledgements

The authors wish to thank CNES and TeSA for support.