Data Center Infrastructure: Data Collection via LAN or Serial Interfaces
TL;DR: Data center infrastructure equipment communicates via two primary interface types: serial (RS232/RS485) using vendor-specific ASCII command protocols, and LAN (Ethernet) using standardized protocols like SNMP with MIBs. Serial interfaces require physical and logical gateway devices for conversion to network-accessible data, while LAN interfaces offer direct, standardized access. For heterogeneous environments with mixed legacy and modern equipment, DCIM platforms like Modius OpenData Collectors can capture and normalize data from both serial and LAN sources.
What Types of Interfaces Exist on Data Center Equipment?
Nearly every piece of equipment built in the last 20 years includes at least one form of core controller interface. The engineering teams that build this equipment will tell you that one of the first portions of a control system developed is the console/monitor access interface, since it is used to develop and debug the controller itself. Every server, switch, router, and firewall, as well as every PDU, UPS, CRAC, and generator, has some form of management interface.
The technology for these interfaces has changed over time. RS232 (and the similar RS485) dominated in the 1970s and 1980s due to simplicity and low cost. With the advent of true networking, Ethernet became popular in the early 1990s for the same reasons and remains the standard interface today. However, the mechanisms for interacting with these two interface types are vastly different.
How Do Serial (RS232/RS485) Interfaces Work?
With serial interfaces, the most common protocol is an ASCII-based text command line protocol. Commands are built using character strings, and results are returned as character strings. For example, a user could send the text command “SHOW SYSTEM UPTIME” and receive “1D 23H10M” (1 day, 23 hours, 10 minutes) in response.
The critical point about command-line interface protocols is that they are specific to each vendor and, in many cases, each model number within that vendor’s catalog. This requires very model-specific device awareness to communicate with serial interfaces.
Serial-to-LAN Gateway Conversion
Since the information retrieved from serial interfaces is ultimately consumed by network-attached servers and monitoring applications, two conversion steps are needed:
- Physical conversion: Getting the information into a format suitable for network transport
- Logical translation: Converting ASCII commands and responses to networked packet values in tables
This is done using a “gateway” device with an RS232 or RS485 port on one side, a small conversion processor inside, and a LAN port on the other side. These gateways are typically purpose-built for specific equipment models.
How Do LAN-Based (Ethernet) Interfaces Work?
LAN-based interfaces are considerably easier to work with. Multiple standardized protocols exist to communicate natively from the device to the network, with the most common being SNMP and its inclusion of MIBs to describe how informational packets are organized.
SNMP (and the MIB) allows a network inquiry to be made against a table of operational values within the target device, with results formatted as expected values within the returned data packet. While there are some detail peculiarities, network-based protocols are much more standardized and widely accepted as the modern approach.
What Does This Mean for Your Data Center Monitoring Strategy?
If a device has a network interface, there is a high probability that you can easily access and understand its performance values without any conversions. Any modern intelligent iPDU (power strip) is a great example: it has a LAN connection and can report power at each outlet and unit temperature via simple SNMP commands. These devices have IP addresses and appear on the corporate network like any other component.
Conversely, if a device has only a serial interface, you will need a physical and logical gateway solution for conversion. These gateways are very specific (purpose-built) for each device model and are usually supplied by the application provider that intends to consume the performance data.
Unified Monitoring Across Mixed Environments
For data centers with a heterogeneous mix of equipment, Modius OpenData Collectors can capture data from both serial and LAN-based infrastructure, normalize it regardless of source protocol, and make it available for monitoring purposes, advanced analytics, or automated control.
Frequently Asked Questions
What is the difference between serial and LAN interfaces on data center equipment?
Serial interfaces (RS232/RS485) use vendor-specific ASCII text command protocols where each manufacturer and model has unique commands. LAN (Ethernet) interfaces use standardized protocols like SNMP with MIBs for structured data exchange. Serial requires gateway conversion hardware; LAN communicates directly over the network.
What is a serial-to-LAN gateway in data center monitoring?
A serial-to-LAN gateway is a device with an RS232 or RS485 port on one side and a LAN port on the other. It performs two conversions: physical (getting serial data onto the network) and logical (translating vendor-specific ASCII commands into network packet values). These gateways are typically purpose-built for specific equipment models.
What is SNMP and why does it matter for data center monitoring?
SNMP (Simple Network Management Protocol) is the most common standardized protocol for monitoring network-connected devices. Using MIBs (Management Information Bases) to describe data organization, SNMP enables any monitoring platform to query operational values from compliant devices without vendor-specific code.
Can DCIM software monitor both legacy serial and modern LAN equipment?
Yes. Modius OpenData Collectors are designed to capture data from both serial and LAN-based infrastructure, normalize the data regardless of source protocol, and make it available for unified monitoring, advanced analytics, and automated control across heterogeneous data center environments.
How common are serial interfaces in modern data centers?
While most equipment manufactured in the last 15-20 years includes Ethernet LAN interfaces, many data centers still contain older serial-only devices, particularly among facilities infrastructure like legacy UPS systems, generators, and older PDUs. A comprehensive monitoring strategy must accommodate both interface types.