IP issues in a LAN can cause network slowdowns, connectivity problems, or even security breaches. If you are experiencing any of these symptoms, you need to troubleshoot the IP configuration and communication of your devices. Here are some steps you can follow to diagnose and fix common IP issues in a LAN.
Before you dive into more advanced troubleshooting, make sure you check the basic elements of your IP network. These include the physical connections, the power supply, the network devices, and the IP addresses. For example, you can verify that the cables are plugged in correctly, the routers and switches are turned on and functioning, and the devices have valid and unique IP addresses. You can use the ipconfig or ifconfig commands to check the IP address, subnet mask, and default gateway of your device.
Know your OSI layers and work your way up, down or devide and conquer. As soon as you prove connectivity at a specific OSI layer, you then know that connectivity in the layers below is a given. Key elements are MAC addresses, ARP tables, routing tables and protocols, and service ports. Last but not least, don't forget that the firewall is part of your network too and may or may not participate in routing decisions.
The below are the basic troubleshooting tips for L3: - use the ping command and check the connectivity between two systems in the LAN. 1. if the ping command is successful then connectivity is good 2. the command shows the round trip time so you can measure how long it takes if you are troubleshooting for delays. 3. Also tcpdump will help to identify the issue since you can see all packets and its response.
The first thing you need to understand about LAN IP. 1. IP Address must be Unique to all your network devices and systems. 2. If you allocate IP Address manually to all device make sure there is no multiple ip or allocate same IP address to any other device. 3. IF you allocate IP address using DHCP Server make sure there is no manual ip in your network. 4. If any manual ip is their in your network make sure that ip exclude in DHCP Server. 5. Finally make sure there is no multiple DHCP server running in your network.
The next step is to ping the default gateway of your device, which is the IP address of the router or switch that connects you to the rest of the network. This will test the connectivity and latency between your device and the gateway. You can use the ping command followed by the gateway IP address to send a series of packets and measure the response time. If you get a reply, it means your device can communicate with the gateway. If you get a timeout or an error, it means there is a problem with the connection or the gateway configuration.
Use Command-Line Tools: Open a command prompt or terminal on the devices experiencing issues. Use commands like ipconfig (Windows) or ifconfig (Linux) to check the IP configuration. Verify that the device has obtained an IP address through DHCP or that a static IP is correctly configured.
If you can ping the gateway successfully, you can try to ping another device on the same network, such as a printer, a server, or another computer. This will test the connectivity and latency between your device and another device on the same LAN. You can use the same ping command followed by the IP address of the other device. If you get a reply, it means your device can communicate with the other device. If you get a timeout or an error, it means there is a problem with the device configuration, the network device, or the network topology.
Subnetting Issues: Ensure that devices within the same subnet can communicate with each other. Check that the subnet mask is consistent across devices.
If you can ping another device on the same network successfully, you can try to trace the route between your device and a remote destination, such as a website or a server on another network. This will test the connectivity and latency between your device and the destination, as well as show you the intermediate hops and devices along the way. You can use the tracert or traceroute commands followed by the destination IP address or domain name to send a series of packets and measure the response time from each hop. If you get a reply from all the hops, it means your device can communicate with the destination. If you get a timeout or an error, it means there is a problem with one of the intermediate devices, the routing table, or the firewall.
Please ensure to: ? Verify the gateway and troubleshoot any connectivity issues. ? Ping the relevant IPs to diagnose connectivity problems. ? Validate the subnet mask configuration for proper IP subnet status. ? Confirm that DNS records are correctly configured. ? If DHCP is utilized, ensure IP reservations are correctly set up.
Update Network Drivers: Ensure that network interface card (NIC) drivers are up-to-date on all devices. Review Logs: Check system logs on devices for any error messages related to networking. Look for clues about IP address conflicts, DHCP issues, or connectivity problems.
If you can trace the route to a remote destination successfully, you can try to check the DNS (Domain Name System) configuration and communication of your device. DNS is the service that translates domain names into IP addresses, and vice versa. If your device has a problem with DNS, it may not be able to resolve the domain names of the websites or servers you want to access. You can use the nslookup or dig commands followed by the domain name or the IP address of the destination to query the DNS server and get the corresponding IP address or domain name. If you get a valid response, it means your device can communicate with the DNS server. If you get an error, it means there is a problem with the DNS server, the DNS settings, or the network security.
Firewall Settings: Verify that firewalls on devices are not blocking necessary traffic. Temporarily disable firewalls for testing purposes (if safe to do so).
- Check STA local settings like IP, SubnetMask, GW, DNS are configured correctly - Verify connectivity with GW - Very DNS resolutions - Check local routing table of the device - For wired devices, check VLAN(tagging) and port security. - Verify if and from where the device MAC is learnt
A few steps: run a ping test to check out the response times. If not getting any response check the DNS or physical layer to the IP host. If reachable and the response time high. Do step two. Step two: run a trace route ( command based on the system operating software). Trace the number of hops to destination IP as well as the response time for each hop to further optimize.
En mi caso lo primero es tener claro el problema y realizar la revisión y análisis por capas. Validar cables de red e incluso eléctrico (tengo una anécdota sobre esto pero la dejaré para otro día) una vez validada la capa física vamos a la parte del enlace (tenemos operativo el servicio con el ISP?) ahora vamos a la configuración de tarjeta de red sea cableado o inalámbrica, validar el uso de dhcp o si contamos con ip estática, validado eso pruebas de comunicación tanto a la red interna como hacia internet (ping, tracert) luego vamos a la red de acceso, backbone o distribución (modelo usado hoy en día) validar vlan, tabla de mac, comunicación hacia el router, luego vamos a la aplicación validar bloqueos y permisos de FW
If none of the above steps help you resolve the IP issues in your LAN, you can try to reset the network settings and devices of your device. This will clear the cache, renew the IP address, and restart the network services and adapters. You can use the ipconfig /flushdns , ipconfig /release , and ipconfig /renew commands to reset the DNS cache, release the current IP address, and request a new IP address from the DHCP (Dynamic Host Configuration Protocol) server. You can also use the netsh command to reset the network stack and the netsh winsock reset command to reset the winsock catalog. Additionally, you can reboot your device, your router, and your switch to refresh the network configuration and communication.