1. Programming Multi-Core Processors based Embedded Systems A Hands-On Experience on Cavium Octeon based Platforms
Lab Exercises

2. Lab # 3: Network Packet Sniffing
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3. Lab Goals Objective Packet capture / filter / analyze - A case study
Learning parallel programming using threads
Utilizing many core systems efficiently
Performance measurement
Packet capture / filter / analyze - A case study
We will use series of labs to achieve our objectives. Today's lab is about packet sniffing
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4. Prerequisites Sniffing Mechanism
Capturing of network packets arriving or departing from a network interface
Mechanism
We use raw sockets as follows
rawSock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL))
This system call picks every packet going out or coming in on an Ethernet interface
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5. Prerequisites Testing
You can use loop back device as a network interface
Use Netperf or MPAC for traffic generation on the network interface
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6. Lab Setup System 1 System 2 1 GigE Link 3-6 Sender Receiver2 4 6 1 3 5 7
Sender
Receiver
Packet Sniffer
1 GigE Link
System 1
System 2
Data Packets
Core
Packet Mapping to Cores
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7. Sniffing Labs Framework
One thread, called the dispatcher, sniffs the packets from the interface and puts it in one of the workers’ queues
Filtering / Analysis
Any kind of processing on a packet is the responsibility of the workers
Each worker has its own queue or shared queue depending on sniffer application architecture
Dispatcher assigns packets to worker queues
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8. Sniffer Application Architecture
MPAC packet sniffer version 1
Single queue
Dispatcher can access whole queue
Each worker thread can access only dedicated locations
In-site sniffing
No copying from dispatcher to worker space
Each location access is mutually exclusive
Controlled by a flag per location
No locking overhead
Get packet, if flag = (workers)
Location Access Function =
Put packet, if flag = (Dispatcher)
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9. MPAC Packet Sniffer (Version 1) T1 T0 TN-1 Dispatcher putting space TN
Dispatcher putting direction
Workers getting direction TN
Worker Threads
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10. Lab 3 – Packet Sniffing Sniff a frame Objective
This lab captures Ethernet packets which are destined to or departing from a specific interface
Objective
Can a dispatcher sniff at the line rate
Hands on experience of plain sniffing
Observing the base case performance of the dispatcher – worker model
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11. Lab 3 - Sniffing Observations
Observe the throughput performance with increasing number of threads
Use core affinity and observe throughput
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12. Cross Compile for Target System
Cross Compile on Host System
Go to Cavium SDK directory and run the command
host$ source env-setup <OCTEON-MODEL>
(where <OCTEON-MODEL> is the model of your target board. E.g. OCTEON_CN56XX)
host$ cd /<path-to-mpac>/mpac_1.2
host$ ./configure --host=i386-redhat-linux-gnu
--target=mips64-octeon-linux-gnu export
CC=mips64-octeon-linux-gnu-gcc
host$ make clean
host$ make CC=mips64-octeon-linux-gnu-gcc
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13. Run on target system
Copy executable “mpac_net_bm” and “mpac_sniffer_app” from the directory mpac_1.2/apps/sniffer/sniffer_MQ_optimized/ on target system
target$ ./mpac_net_bm –c <Receiver> –d <duration>
–l <# of threads>
target$ ./mpac_net_bm –c <Sender> –d <duration>
–l <# of threads> -i <IP of Receiver>
target$ ./mpac_sniffer_app –n<# of Threads> –d<duration>
-f<interface to sniff> -e 3
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14. Lab 3 – Sniffing (MPAC sniffer version 3)
$ ./mpac_sniffer_app -f eth0 -d 30 -e 3 -q n <# of Threads>
$ ./mpac_sniffer_app -f lo -d 30 -e 3 -q n <# of Threads>
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