Every network-enabled device has 2 types of addresses, logical (IP addresses) and physical (MAC addresses). An IP address (Internet Protocol address) is the address that is assigned to your device by the network. It uses Internet Protocol for communication. These IP addresses can change. The IP address is used to permit other network devices to use the address when communicating with other hosts. The IP address is part of layer 7 in the OSI model. Each host on a TCP/IP network has an assigned 32-bit logical address. This address is divided into 2 parts, the Network Number and Host Number. The Network Number identifies the network and is assigned by the InterNIC (Internet Network Information Center). The Host Number identifies a host in the network and is assigned by the local network administrator.
To troubleshoot IP addresses and IP connectivity, using a show IP route command will list all available routes and what interface is used to reach the specific IP address and network. After this is completed, the ping and trace command can both be useful. The ping command will use the ICMP protocol to verify the reachability and status of a host. The traceroute command is used to display the gateways used to reach a destination host. By using these commands, troubleshooting IP addresses should be relatively simple.
A MAC address is a hardware address. This means it is unique to the network card in your device. Being so, no devices should ever have the same MAC address; if this does happen, many problems will arise. The MAC address is permanently installed into the network card during the manufacturing process. MAC addresses are used at layer 2 of the OSI model. The MAC address is a 12-digit hexadecimal number or 48-bits in length. If a computer’s network card is replaced, you might have to reconfigure several systems to work with the new MAC address. Network switches generally store a list of MAC addresses that are seen at every port, which allows them to only forward packets to the ports needed. Wireless access points also use MAC addresses for access control; they only permit known devices (MAC addresses).
References:
King, Michael. (2011). How to Find Your IP Address and MAC Address. Retrieved from https://www.pcworld.com/article/240803/how_to_find_your_ip_address_and_mac_address.html.
Tetz, Edward. (n.d.). Cisco Networking: MAC Addressing. Retrieved from http://www.dummies.com/programming/networking/cisco/cisco-networking-mac-addressing/.
Categories: Networks
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