Run wireshark on your DHCP server to verify you are seeing the clients DHCP discover making it to your server and that the response has the correct destination MAC address.Run packet captures off your other devices along the path between the client and the DHCP server.Ensure the switches uplink has the correct allowed VLANs if using VLANs and VTP within your infrastructure.Verify 802.1q is correct setup on the Switch port.If you are not seeing a response back, here are some other things worth looking into: The two most common problems are: 1-) The client device never receives a response from the DHCP server or 2-) The client device gets an IP from the wrong DHCP server.įor the latter, please take a look at the following KB - Tracking down a rogue DHCP server Figure 5 shows my client device "Source: f0:de:f1:a3:5d:d6 " sending out a broadcast to "Destination ff:ff:ff:ff:ff:ff " and Figure 6 shows the available DHCP server "Source: 00:18:0a:42:3e:b5 " responding back to my client with a DHCP Offer. Validate your host device is sending out a discovery broadcast, and 2-) we want to validate the DHCP server is responding back. The figure bellow shows the four-way DHCP process as well as the the Transaction ID which is very important as this groups each DHCP process/handshake together:įigure 5: Packet capture illustrating the DHCP handshakeĦ. This filter will show any part of the DHCP process in the capture: DHCP discover, DHCP offer, DHCP request, DHCP acknowledge.This will give you great insight of where the DHCP process is potentially failing. Perform this step a few times in order to generate traffic that is being captured by the packet capture toolĥ. Open the saved PCAP file which has been downloaded from Dashboard with Wireshark and enter the bootp display filter, click Apply. If your DHCP server is connected to the same switch you will want to capture off the specific port the client is connected to instead of the uplink.įigure 3: Packet capture view on DashboardĤ. Open the Command prompt from the client machine and perform an ipconfig /release then ipconfig /renew. This will force the client machine to perform a DHCP broadcast.
#Handshaker mac review download#
You will need to set your packet capture tool to download file to PCAP file and capture for 60 seconds. Set up your packet capture tool to gather data from the switch uplink port and the client on the same switch. Navigate to Monitor > Packet capture. In a combined network you will want to navigate to N etwork-wide > Packet capture and select which Cisco Meraki Appliance you would like to capture off of:Ģ. The DHCP handshake is illustrated in Figure 1 below.ġ. In this example, a client device is connected to a Cisco Meraki switch port but is unable to get IP information from the DHCP server. This requires Wireshark installed in order to open PCAP file that will be downloaded from Dashboard.
#Handshaker mac review how to#
This article describes how to use the Packet capture tool in Dashboard to troubleshoot client-side DHCP issues on your network. Using Packet Capture to Troubleshoot Client-side DHCP Issues
0 kommentar(er)
