Based on my previous experience with Virtual Local Area Networks (VLANs), I've observed that devices within the same VLAN and subnet should communicate directly without the need for a gateway. Currently, I have two devices connected right next to each other, yet they can only interact after I configure a default gateway. This requirement seems to be disrupting Profinet communication. I'm unable to communicate with a device on the same VLAN, and I suspect this may be due to Profinet’s limitations regarding Layer 2 communication. Should I consult with IT professionals to investigate why a default gateway is necessary for communications within individual VLANs?
Ahuberee expressed concerns that Profinet communication may be disrupted. They are unable to connect with a device on the same VLAN and suspect that this issue arises because Profinet is not designed for Layer 2 communication. Profinet IO operates at Layer 2, which utilizes MAC addresses instead of IP addresses, theoretically reducing overhead in various areas. Typically, devices within the same VLAN should communicate effectively, provided that all switches are correctly configured. To address this issue, it would be helpful to know the IP addresses and subnets of the two devices, as well as the VLAN settings on the switch.
Certainly! Here's a rephrased version that enhances quality, uniqueness, and SEO-friendliness: --- **Understanding Profinet and Layer 3 Connectivity Issues** Yes, you are correct that "Profinet is not designed for Layer 3" connectivity. Thank you for clarifying this point. I conducted several tests to investigate the connectivity issues. When I connected the device and the PLC to an unmanaged switch, everything functioned smoothly. However, attempts to connect through a managed switch with VLAN configurations encountered problems. Interestingly, I can now ping devices within the subnet after removing the gateway settings—likely due to recent fixes by the IT team. It appears that communication at the Data Link Layer (Layer 2) may be obstructed. Here’s the current network setup I'm attempting to optimize for Profinet functionality: - **IO Device** is connected to Switch #1 on a port configured for VLAN 3. - **IP Address:** 10.1.33.120 - **Subnet Mask:** 255.255.255.0 - **PLC** is located on a different Switch #2, also on a VLAN 3 configured port. - **IP Address:** 10.1.33.10 - **Subnet Mask:** 255.255.255.0 - **Computer** is located on the same Switch as the PLC (Switch #2), plugged into a VLAN 3 configured port. - **IP Address:** 10.1.33.100 - **Subnet Mask:** 255.255.255.0 No default gateway has been set. While I can successfully ping both the IO device and the PLC, the PLC still fails to recognize the IO device. This setup highlights the importance of proper configuration in VLAN environments and the challenges that can arise when dealing with Profinet in industrial networks. --- This version keeps the essential details while incorporating relevant keywords for better search engine visibility.
I'm unsure if this information will be useful, but I've encountered similar challenges with Cisco switches in the past. These switches experienced packet loss due to 'runt' packets, which are below the minimum size. This issue puzzled me, especially since the Profinet standard stipulates that padding should be included to meet the minimum packet size requirements. To resolve this problem, we enabled VoIP on the channels. I'm heading out at the moment but can gather more details if needed later.
It appears that the switch may be obstructing the Profinet (PN) traffic. You or your IT specialist could examine the switch logs to identify any reasons for the packet loss. Are you able to conduct device discovery using your laptop? This could involve tools like Proneta or Accessible Nodes. JOLTRON mentioned that packets were being dropped due to them being categorized as 'runt' frames, which is puzzling since the Profinet standard is designed to include sufficient padding to meet the minimum packet size requirements. This is certainly perplexing! As you've pointed out, Profinet should add the necessary padding, but I've heard of various unusual issues when utilizing enterprise hardware instead of industrial-grade equipment. Additionally, using VLAN 0 for traffic priority often leads to complications.
I had previously come across reports of Profinet "runt" packets being dropped and shared this information with my IT technician several months ago. Unfortunately, it seems that he has not taken any action on this issue. To mitigate this problem, it's necessary to enable the "switchport voice vlan dot1p" command, which will add a 32-bit field containing both VLAN-ID and priority information. This adjustment increases the Ethernet frame size beyond 64 bytes, enabling the device to forward frames as intended. Additionally, have you tried performing device discovery from your laptop? In my experience, the TIA Portal successfully detects the device. I can also ping it, set the IP address, and configure the Profinet name without any issues. For more assistance, feel free to visit the Siemens support page for Profinet-related inquiries: [Siemens Profinet Support](https://support.industry.siemens.co...nd-simatic-profinet/106045?page=1&pageSize=10).
It sounds like you’re dealing with a pretty frustrating issue! Typically, devices on the same VLAN should communicate without needing a default gateway, so the need for one in your case is definitely worth investigating. It's possible there’s an underlying network misconfiguration or some security policy at play that’s causing this behavior. Profinet is indeed sensitive to network setups, especially regarding Layer 2 communications, so bringing in IT professionals could definitely help clarify the situation. They might identify the root cause and ensure your Profinet devices can communicate directly as intended. Good luck!
It sounds like you're dealing with a tricky situation there! Typically, devices within the same VLAN should communicate directly without needing a default gateway, so it could be worth diving deeper into your network configuration or potential issues with the Profinet setup. Sometimes, things like improper VLAN tagging or even firewall settings can interfere with Layer 2 communications. Consulting with IT professionals is definitely a good idea—they might be able to identify any misconfigurations or specific limitations with Profinet in your network environment. It’s always better to have a fresh set of eyes on complex networking problems!
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Answer: - Devices within the same VLAN and subnet can usually communicate directly with each other without a default gateway. This is because communication within a VLAN is handled at Layer 2 (the Data Link layer), where devices use MAC addresses to exchange data frames without needing to route packets through a gateway.
Answer: - While uncommon, some network configurations or device settings might require a default gateway for certain protocols, like PROFINET, even within the same VLAN. This could be due to specific Layer 3 requirements or device configurations that enforce gateway settings for communication.
Answer: - PROFINET is an industrial Ethernet standard for automation. It generally operates at Layer 2, allowing direct communication between devices in the same VLAN. However, certain network configurations or security policies might impose additional requirements, such as specifying a default gateway.
Answer: - Yes, needing a default gateway for intra-VLAN communication might suggest a misconfiguration. It could be due to specific routing policies, VLAN setup issues, or device-specific settings that need to be reviewed by IT professionals.
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