lab4 - Lab4: Network Monitoring and Debugging (Part I/II)...

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ab4: Network Monitoring and Lab4: Network Monitoring and ebugging (Part I/II) Debugging (Part I/II) • Network trouble shoot tools – ifconfig, netstat, iperf, arp, ping, aceroute traceroute • Traffic analysis by tcpdump – TCP and UPD data packets capture IEG 7006 (2010) 1
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Lab4: Network Monitoring and Debugging Network trouble shoot tools config ifconfig It provides information about the basic configuration of the interface. It is useful for detecting bad IP addresses, incorrect subnet masks, and improper broadcast addresses E.G. csh> ifconfig -a eth0 Link encap:Ethernet HWaddr 00:D0:09:28:F9:F9 inet addr:192.168.64.23 Bcast:192.168.64.255 Mask:255.255.255.0 P BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:10113996 errors:231 dropped:0 overruns:0 frame:231 TX packets:2575002 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 Interrupt:3 Base address:0xc000 IEG 7006 (2010) 2
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Lab4: Network Monitoring and Debugging Network trouble shoot tools heck for the error packets and collision values Check for the error packets and collision values The Input errors/Input packet ratio and Output errors/Output packet ratio should be < 0.025 % arge Input errs => the interface just discards the packet Large Input errs => the interface just discards the packet there may be faulty hardware on the network (Faulty hardware can be anything from another computer system that is generating packets improperly to a bad connector or terminator) r your system cannot receive packets fast enough or your system cannot receive packets fast enough IEG 7006 (2010) 3
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Lab4: Network Monitoring and Debugging Network trouble shoot tools heck for the error packets and collision values Check for the error packets and collision values Large Output errs => your system's network interface is faulty something wrong the CPU and the ethernet cable the problem should be local not from outsiders Collisions are normal events and don't indicate hardware problems. However, if Collision/Output packets > 10 % constantly => network ,p p y overloaded IEG 7006 (2010) 4
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Lab4: Network Monitoring and Debugging Network trouble shoot tools heck for the error packets and collision values Check for the error packets and collision values Besides "ifconfig -a", "netstat -i" and "cat /proc/net/dev" can also show the Input and Output packet statistics g e.g ntec23:/tmp> netstat -i Kernel Interface table Iface MTU Met RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg eth0 1500 0 10153378 231 0 0 2588097 0 0 0 BRU lo 3924 0 14174 0 0 0 14174 0 0 0 LRU IEG 7006 (2010) 5
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Lab4: Network Monitoring and Debugging Network trouble shoot tools Measure the throughput between two points iperf At the receive side, erf - iperf s At the send side, iperf -c receive_side_host_name or example, For example, ntec11-48:/root> iperf -l 2M -c ntec12-48 ------------------------------------------------------------ lient connecting to ntec12 8 TCP port 5001 Client connecting to ntec12-48, TCP port 5001 TCP window size: 58.6 KByte (default) ------------------------------------------------------------ [ 3] local 192.168.248.21 port 3809 connected with 192.168.248.22 port 5001 [ 3] 0.0-10.5 sec 52.0 MBytes 41.6 Mbits/sec IEG 7006 (2010) 6
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Lab4: Network Monitoring and Debugging Network trouble shoot tools
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This note was uploaded on 05/18/2010 for the course INFORMATIO IEG7006 taught by Professor Unknown during the Spring '10 term at CUHK.

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lab4 - Lab4: Network Monitoring and Debugging (Part I/II)...

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