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Chapter 7bge1 1500 00:16:35:80:ac:52 19972917 52791 222198790 0bge1 1500 81.91.129.64/ devbox 19755146 -22207004 - -This example shows the statistics for the bge1 network interface. There are two linesof statistics, one for the layer2 protocol (Ethernet in this example) information andanother for layer3 protocol (IP in this example).The first (after the header) indicates the interface name, current MTU size, Networkinformation (which is not available in layer2), address (which is MAC addressin layer2), number of Input Packets, number of Input Errors , Number of outputpackets, Number of output errors and finally the number of detected collisions onthe interface. The next line displays the same information (if applicable) for layer3.The information that is useful for troubleshooting is the number of packets, andmore importantly, the number of errors that might be caused due to faulty hardware.ARPFreeBSD maintains a layer2-to-layer3 address mapping database called ARP table.ARP is thoroughly explained in RFC 826. The arp(8) utility is used to manipulatethe system's ARP table.While the system automatically takes care of updating and refreshing the ARPdatabase, the systems administrator can manipulate (add or remove) the ARPdatabase entries, when needed. The arp(8) utility is used to display the contents ofthe system's ARP table:# arp -an? (172.21.0.13) at 00:10:db:58:4d:49 on bge1 [ethernet]? (172.21.0.1) at 00:11:0a:9c:fe:c5 on bge1 [ethernet]? (192.168.2.133) at 00:02:b3:8c:9f:c2 on bge1 [ethernet]If you want to remove a specific ARP entry from the table, you may use thearp –d command:# arp -d 172.21.0.1172.21.0.1 (172.21.0.1) deletedYou can also use the arp –d –a command to clean up the ARP table by removing allexisting entries.[ 125 ]