In the technical data of the Managed Industrial Switches, L2, L2+, and L3 are the most frequently used in switch management level. Many people always easy to confuse them and after reading this article, you can understand the main difference between them, and it will become easy for choosing switch.
I. Managed Industrial Switches: Layer 2 Unmanaged Industrial Switch
The device operates at the data link layer and forwards traffic entirely based on the MAC address table. It has no Layer 3 routing capability and cannot realize communication across different IP subnets.The product is located in the field access layer equipment, which is responsible for the data access and forwarding of the same network segment.
The software agreement of the Layer 2 network type industrial switch, such as Cisco Industrial Managed Switches and MOXA Industrial Switches, is all around the stable communication and operational design of the network segment, covering basic Ethernet communication, link polymerization and flow control, ensuring the normal network of ports and bandwidth redundancy; Support for redundant agreements such as RSTP/MSTP. The network isolation is implemented through VLAN, and balanced security & anti-interference. It is equipped with web/command line, SNMP batch monitoring, port image, DHCP, log alarm, etc., for convenient remote configuration and fault checking. To coordinate the safety mechanism of portauthentication, broadcast storm suppression, encryption login, etc., to improve the protection of the network; Support QoS priority scheduling and group broadcast optimization, ensure that key data such as industrial control and video are transmitted stable. Provide NTP or PTP capabilities; All functions of the whole work in the Layer 2 network category, do not have the Layer 3 route forwarding ability of cross-ip segment.
2. Layer 2+ Light Layer 3 Managed Industrial Switches
The equipment is centered on layer 2, and the simple Layer 3 forward engine is usually built, and the VLANIF Layer 3 virtual interface and static routing can be configured to realize the interconnectivity between different VLAN and different networks. No dynamic routing protocol such as OSPF、BGP and the number of routing items is usually in dozens of levels. In general, the ability of ACLand QoS scheduling and group broadcast management also increased.
3. Layer 2 Managed Industrial Switches
In addition to supporting static routing, it also supports the major dynamic routing protocol such as RIP v2、OSPF. It supports Super VLAN, VLAN aggregation and QinQ termination. Compatible with dynamic routing protocols, it enables full intercommunication of multiple VLANs across devices and regions.
4.FAQ
Question :l2 + ,compare the l2 industrial switches. What additional core functions are supported?
Answer: l2 + is the cost-effective method of industrial scenario, adding the core value added function on the basis of l2;
Static routing enables inter-VLAN communication without an extra router.
IP-based ACL access control and IPv6 management are supported.
Enhanced QoS traffic scheduling and complete 802.1X port security functions available.
Improve industrial ring network (ERPS/MSTP) and group broadcast optimization (IGMP Proxy); l2 only have basic Vlan, simple STP, basic port speed limit, no IP layer control capability.
Question : What is the core functional difference between L2+ and L3 switches?
Answer: the core difference is on the dynamic routing protocol:
L2+：Only supported static route; all network segments must be manually configured, with no capability to dynamically learn full-network routes.
L3: Supports dynamic routing protocols including OSPF and RIP, enabling automatic route synchronization across multiple factory zones and subnets, be suitable for large-scale hierarchical industrial networks. Additionally, L3 switches support Layer 3 SVI virtual interfaces, policy-based routing, and full IP-layer firewall control.
Question: Which layer does PTP or 1588v2 belong to?
Answer: IEEE 1588 PTP v2 (Precision Time Protocol) is not strictly mapped to a single network layer and can operate at Layer 2 or Layer 3;
Layer 2: Encapsulated directly within Ethernet frames with an EtherType value of 0x88F7. It requires no IP addressing and works seamlessly over Layer 2 networks. This is the most widely deployed mode in industrial sites, so Layer 2 managed switches can support PTP v2 functions.
Layer 3: Carried via UDP (UDP ports 319, 320) and transmitted via IP networks. It requires Layer 3 IP reachability and is mainly used for distributed time synchronization across multiple network segments over a wide coverage area.
In short, PTP itself is not a Layer 3 routing function and has no mandatory binding to the Layer 2/Layer 3 managed industrial network switch. Layer 2, L2+ and Layer 3 switch models including different types of managed switches, can all be equipped with PTP time synchronization capability, which answers the question of what do managed switches do. In most industrial scenarios, PTP runs at Layer 2 protocol.
Question: Which layer does TSN belong to?
TSN (Time-Sensitive Networking) is not a single protocol, but a suite of Layer 2 deterministic communication standards. Its core capabilities including time synchronization (802.1AS/gPTP), time-aware scheduling (802.1Qbv), frame preemption (802.1Qbu), stream reservation (802.1Qcc) and seamless redundancy (802.1CB) are all processed based on Ethernet frame headers and VLAN priority tags. No IP addresses are required for addressing, and the full set of functions can operate entirely over Layer 2 networks.
4. Summary
Based on the above analysis for interface types, L2/L2+/L3 switching layers and protocol systems, you can clearly distinguish the functional positioning and product forms of different managed industrial switches, and compare factors such as managed switch price when selecting suitable managed industrial devices.
The agreement support range and functional capacity set of industrial switch is determined by the main control SOC chip, and the different hardware platform corresponds to different forward performance and functional boundary, and the product pricing is also differ.
Rayin Technology always adheres to labeling product specifications and parameters in full compliance with relevant standards and provides users with transparent, reliable network equipment selection scheme.
