dayonixe / n7_realtimenetworkdeployment

Project realized within the course of Real Time Network Deployment at the ENSEEIHT.

Project - Real Time Network Deployment

Team : Nouhaila A. & Théo Pirouelle

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The AFDX switch is a software switch and is made with FPGA cards in airplanes.

A first attempt

Machine without DPDK

We modify the file send.py by thinking to modify the port of sending in the file :

#!/usr/bin/env python
from socket import *
import time

# opening a raw socket on eth0
socket= socket(AF_PACKET, SOCK_RAW)
socket.bind(("eth3", 0))                    # Sending port

# src and dest addr configuration
# ici src=dst=00:01:02:03:04:05
src_addr="\x00\x01\x02\x03\x04\x05"
dst_addr="\x00\x01\x02\x03\x04\x05"

# payload = chaine of 1000 characteres *
payload=("*"*1000)

# checksum non calcule = 0x00000000
checksum="\x00\x00\x00\x00"

# 0x0800 = IPv4
ethertype="\x08\x00"

socket.send(dst_addr+src_addr+ethertype+payload+checksum)

socket.close()

Machine with DPDK

After sending the machine without DPDK a packet to port number 1.

Result obtained:

> ./build/l2fwd -- -p 0x3

Port statistics ====================================
Statistics for port 0 ------------------------------
Packets sent:                        1
Packets received:                    0
Packets dropped:                     0
Statistics for port 1 ------------------------------
Packets sent:                        0
Packets received:                    1
Packets dropped:                     0
Aggregate statistics ===============================
Total packets sent:                  1
Total packets received:              1
Total packets dropped:               0
====================================================

We put the 0x3 to say that we use port 0 and port 1.

Switching table used:

src	dst
0	1
1	0

The switch table is in the file l2fwd.

Implementation of AFDX switching

In this PW, we have chosen to make a direct access data structure. That is to say, we made a table in the first part when we did not manage the multicast VLs. In the second part, we made a list. This allows to reduce the execution time of the code.

We also chose a static allocation because we have to take into account all the VLs we have (65536). Even if we don't use all the VLs.

Machine without DPDK

To test, we modify the destination address:

#!/usr/bin/env python
from socket import *
import time

# opening a raw socket on eth0
socket= socket(AF_PACKET, SOCK_RAW)
socket.bind(("eth3", 0))

# src and dest addr configuration
# ici src=dst=00:01:02:03:04:05
src_addr="\x00\x01\x02\x03\x04\x05"
dst_addr="\x00\x01\x02\x03\x00\x01"  # The last two bytes to modify for the VL_ID

# payload = chaine of 1000 characteres *
payload=("*"*1000)

# checksum non calcule = 0x00000000
checksum="\x00\x00\x00\x00"

# 0x0800 = IPv4
ethertype="\x08\x00"

socket.send(dst_addr+src_addr+ethertype+payload+checksum)

socket.close()

Machine with DPDK

In a first step, we set up a switching table using lists, and for each VL number we associate a random port between 0 and 1 of dimension 65536. For example:

VL number	Port number
0	0
1	1
2	1
3	1
4	0
5	1
6	0
7	0
...	...
65536	1

The switching table is filled with a random number between 0 and 1 as follows:

for (i=0 ; i<65536 ; i++) {
	dest_VL[i]=(int)(rand()/(double)(RAND_MAX+1)*2);
}

We retrieve the VL number from the destination address and retrieve the destination port from the VL number and the switch table and initialize t to calculate the execution time, as follows:

eth = rte_pktmbuf_mtod(m, struct ether_hdr *);
tmp1 = eth->d_addr/addr_bytes[4];
tmp2 = eth->d_addr/addr_bytes[5];
vl = (tmp1 << 8) + tmp2; 
dst_port = l2fwd_dst_ports[dest_VL[VL]];
t = rte_get_timer_cycles();

and we add this line just after sending the packet to recover the execution time which corresponds to the memory reading time of the destination port of the switching table:

t = (1000000*(rte_get_timer_cycles()-t)/rte_get_timer_hz());

The execution time is $1µs$, and we obtain the following result:

> ./build/l2fwd -- -p 0x3

Port statistics ====================================
Statistics for port 0 ------------------------------
Packets sent:                        3
Packets received:                    0
Packets dropped:                     0
Statistics for port 1 ------------------------------
Packets sent:                        2
Packets received:                    5
Packets dropped:                     0
Aggregate statistics ===============================
Total packets sent:                  5
Total packets received:              5
Total packets dropped:               0
====================================================

As you can see the program uses the switching table to send the packets that correspond to each VL to the right port.

The VLs are multicast

For the multicast VLs, we have chosen to modify the data structure we used for the first configuration. We created a list of list of dimension $65536*2$. As follows:

// We initialize the VL 0 for the test              
dest_VL[0][0]=1;
dest_VL[0][1]=1;
for (i=1;i<65536;i++) {
	// We initialize the rest with a random value between 0 and 1
	dest_VL[i][0]=(int)(rand()/(double)(RAND_MAX+1)*2);
	dest_VL[i][1]=(int)(rand()/(double)(RAND_MAX+1)*2);
}

Each VL will have a list of two dimensions. For example, for VL number i: if dest_VL[i][0]=1 and dest_VL[i][1]=1 then the VL is multicast and we send on both ports. Otherwise, we send on port number dest_VL[i][0].

The execution time is $1µs$.

We use the following code:

// If the VL is multicast
if (dest_VL[VL][0]==1 && dest_VL[VL][1]==1) {
	buffer = tx_buffer[1];
	sent = rte_eth_tx_buffer(1, 0, buffer, m);
	if (sent)
		port_statistics[1].tx += sent;
	buffer = tx_buffer[0];
 	sent = rte_eth_tx_buffer(0, 0, buffer, m);
	if (sent)
		port_statistics[0].tx += sent;
} else {
	dst_port = l2fwd_dst_ports[dest_VL[VL][0]];
	buffer = tx_buffer[dst_port];
	sent = rte_eth_tx_buffer(dst_port, 0, buffer, m);
	if (sent)
		port_statistics[dst_port].tx += sent;
}

We can see that the machine without DPDK received 14 packets and sent 17 so there are 3 packets that were multicast.

> ./build/l2fwd -- -p 0x3

Port statistics ====================================
Statistics for port 0 ------------------------------
Packets sent:                        8
Packets received:                    0
Packets dropped:                     0
Statistics for port 1 ------------------------------
Packets sent:                        9
Packets received:                    14
Packets dropped:                     0
Aggregate statistics ===============================
Total packets sent:                  17
Total packets received:              14
Total packets dropped:               0
====================================================

VL control at the input

Machine without DPDK

We modify the send.py file to be able to loop without sending to the same recipient :

#!/usr/bin/env python
from socket import *
import time
import sys
import binascii

# Checking the parameter
if len(sys.argv) == 1:
	print("Ca marche pas, il y a un probleme !!!")
	print(sys.argv)
	exit()

# opening a raw socket on eth0
socket= socket(AF_PACKET, SOCK_RAW)
socket.bind(("eth3", 0))

# src and dest addr configuration
src_addr="\x00\x01\x02\x03\x04\x05"      # ici src=00:01:02:03:04:05
dst_addr="\x00\x01\x02\x03\x00" + binascii.unhexlify("0"+sys.argv[1])

# payload = chaine if 1000 characteres *
payload=("*"*1000)

# checksum non calcule = 0x00000000
checksum="\x00\x00\x00\x00"

# 0x0800 = IPv4
ethertype="\x08\x00"

socket.send(dst_addr+src_addr+ethertype+payload+checksum)

socket.close()

#!/bin/bash

while :
do
	randNumber=$((RANDOM % 9))
	echo "VL numero : ${randNumber}"
	./sendv2.py $randNumber
	sleep 1
done

When we run the end_system.sh script, we get the following display:

VL numero : 5

VL numero : 1

VL numero : 7

VL numero : 0

VL numero : 3

VL numero : 0

VL numero : 1

VL numero : 7

VL numero : 2

VL numero : 5

VL numero : 7

VL numero : 8

VL numero : 8

Machine with DPDK

After executing the end_system.sh script, we get the following display:

> ./build/l2fwd -- -p 0x3

Port statistics ====================================
Statistics for port 0 ------------------------------
Packets sent:                        7
Packets received:                    0
Packets dropped:                     0
Statistics for port 1 ------------------------------
Packets sent:                        9
Packets received:                    11
Packets dropped:                     0
Aggregate statistics ===============================
Total packets sent:                  16
Total packets received:              13
Total packets dropped:               0
====================================================

numero de VL : 5
le temps d'execution : 1 µs

numero de VL : 1
le temps d'execution : 1 µs

numero de VL : 7
le temps d'execution : 1 µs

numero de VL : 0
le temps d'execution : 1 µs

numero de VL : 3
le temps d'execution : 1 µs

numero de VL : 0
le temps d'execution : 1 µs

numero de VL : 1
le temps d'execution : 1 µs

numero de VL : 7
le temps d'execution : 1 µs

numero de VL : 2
le temps d'execution : 1 µs

numero de VL : 5
le temps d'execution : 1 µs

numero de VL : 7
le temps d'execution : 1 µs

numero de VL : 8
le temps d'execution : 1 µs

numero de VL : 8
le temps d'execution : 1 µs