Also, look for apps that are both using a lot of CPU time and that need the high-performance GPU (look under the Requires High Perf GPU column in Activity Monitor).Īlternatively, it's possible that an application - or maybe even the operating system - has crashed and is going rogue. You can check to see if you have any system-intensive applications by opening up Activity Monitor and looking for anything that's consuming a lot of CPU time (anything over 80 percent in the % CPU column). After all, without them, your Mac would quickly wither and die. If you are running a resource-heavy application such as Photoshop, or have a browser with loads of tabs open, then the fans might very well be just doing their job. See also: Five Apple products that are headed for the scrapheapįirst of all, it may just be normal.
This command means something completely different than the switch command show mac address-table.Are the fans in your Mac or MacBook roaring away at full speed, making it sound like your computer is getting ready to take off? Here are some simple things you can try that might save you a trip to the Apple Store. How many MAC addresses are in the table? Why?
The gateway address of the router interface is stored in the IPv4 configuration of the hosts.
The destination IP address is not 10.10.10.1.What is the target destination IP destination address of the ARP request? Enter arp -d to clear the ARP table and switch to Simulation mode.What is the IP address of the new ARP table entry? Part 3: Examine the ARP Process in Remote Communications Step 1: Generate traffic to produce ARP traffic. Why are two MAC addresses associated with one port?īecause both devices connect to one port through the Access Point. Enter the show mac- address-table command. Enter the show mac- address-table command.ĭo the entries correspond to those in the table above? Click 10.10.10.2 and open the Command Prompt.Ĭlose a command prompt Step 2: Examine the MAC address table on the switches.Part 2: Examine a Switch MAC Address Table Step 1: Generate additional traffic to populate the switch MAC address table. When it does not know the receiver’s MAC address. In general, when does an end device issue an ARP request? To what IP address does the MAC address entry correspond? Click 172.16.31.2 and enter the arp – a command.Switch back to Realtime and the ping completes.Open the PDU and examine the MAC addresses.ĭo the MAC addresses of the source and destination align with their IP addresses? How many copies of the PDU did the switch make during the ARP reply? Click Capture/Forward until the PDU returns to 172.16.31.2.Source became destination, turned into MAC address of 172.16.31.3 What happened to the source and destination MAC addresses? What is the IP address of the device that accepted the PDU? How many copies of the PDU did Switch1 make? Click Capture/Forward to move the PDU to the next device.Is this address listed in the table above? Open the PDU and record the destination MAC address. The ARP PDU moves Switch1 while the ICMP PDU disappears, waiting for the ARP reply. So the computer sends an ARP broadcast frame to find the MAC address of the destination. The ping command cannot complete the ICMP packet without knowing the MAC address of the destination. Enter Simulation mode and enter the command ping 172.16.31.3.Enter the arp -d command to clear the ARP table.
Click 172.16.31.2 and open the Command Prompt.Instructions Part 1: Examine an ARP Request Step 1: Generate ARP requests by pinging 172.16.31.3 from 172.16.31.2.
You will gather PDU information in simulation mode and answer a series of questions about the data you collect. This activity is optimized for viewing PDUs. Part 3: Examine the ARP Process in Remote Communications Background Part 2: Examine a Switch MAC Address Table