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The need for centralized management and monitoring

Centralized management and control are essential for Data Centers and other applications such as High Performance Clusters. Managers want to minimize the time and effort required to setup, configure, and operate large installations. Problems need to be identified before they create downtime and impact tasks that have long execution times. Failures are expensive in these environments, which makes management a critical factor in delivering application performance.

Centralized monitoring and management solutions using serial access (also known as console management or serial console) have been developed to address these types of challenges, reduce the risk of downtime, and lower operational costs. Today's serial console access systems have port densities and security features that make them a good choice for cluster management.

Importance of Out of band Management Access

In-band vs. Out of band

Management using the network that connects the nodes can be accomplished in-band, where the control and management data shares the same network as the data being processed, or out-of-band, where a separate network is maintained for management and control data. Using the in-band approach has its drawbacks. Management data must share the network bandwidth while resource and network failures can result in the infrastructure becoming unmanageable. An out of band management (OOB) option provides alternate access. Therefore, having a reliable out-ofband network is vital for accessing systems and devices in case of network failure.

Console Servers and Out-of-Band Management

Console servers have been developed to provide a way for users to access many serial devices from one centralized location. The console server terminates all the serial connections from each of the nodes in the cluster and provides management access to each cluster node. Console servers also include a network connection so that users can connect to the server and then to a node through a telnet or SSH connection.

Secure Out-of-Band Management

Most console servers have a CPU, embedded operating system, memory for running the embedded operating system (OS), non-volatile RAM (NVRAM) to record the settings and configuration, one or two network ports for remote access, and many RS-232 ports to connect to servers. Console servers are also widely used for managing communication devices such as modem pools, PBX, network switches, routers, and other devices. The communication standard currently used between the serial port concentrators and the nodes is EIA RS-232C. Most console servers use Category-5 (Cat-5) cables to replace the thick RS-232 full specification serial cables to reduce the thickness that often create cabling management difficulties.

Several reasons for selecting out-of-band management include:

Parallel Management

Out-of-band access allows parallel management of all devices. Broadcast functions facilitate remote installation, updates, and upgrades to the operating system and any software or applications on servers. Configuration scripts can be managed and applied in parallel to the devices. System administrators can use the broadcast function to perform operations on all devices simultaneously: remotely modifying the BIOS settings, editing, copying, and deleting files, and rebooting all nodes in a cluster.

Security Risk Reduction

Removing the management traffic from the in-band network provides enhanced security. The out- solutions provide specialized user interfaces and will limit the risk of virus introduction and unauthorized There are a variety of authentication protocols in use today, including Radius, SecurID and TACACS+.

Fault Analysis and Recovery

When in-band network failures cause a node to become unreachable, the out-of-band network allows the administrator to conduct fault analysis and access the node to carry out corrective actions without affecting the applications that are using the in-band network.

Network Traffic Reduction

Management and control network traffic is moved to the out-of-band network, allowing applications to take advantage of all the in-band network bandwidth.

Management Selection Criteria for Out-of-Band Management Solutions

Since many types of out-of-band management devices are available, it is necessary to understand the selection criteria and other factors to reduce potential implementation risks. These include:

Remote Accessibility and Manageability

A remote site can connect to a management device through a modem or network. The ability to manage and operate servers in a data center or cluster remotely provides various features such as remote diagnostics and joint debugging. Several factors to consider include bandwidth, number of remote login sessions, interface usability, port density, port replication and security level.

MRV's In-Reach products support high port densities that are an attractive match for data centers or high performance clusters. There are flexible options for remote accessibility (Telnet, SSH, optional V.90 modem support) with the best security and ease-of-use in the industry.


Today, many data centers are responding to increased security threats in a variety of ways, including disabling Telnet access to key servers and devices. Console servers can support a wide range of security capabilities, including protocols such as Radius, SecurID, TACACS, etc. Dialback capabilities can ensure that only known entities at specific locations can gain access. SNMP V3 provides encryption for secure access by centralized management applications.

The In-Reach LX Series offers support for all of these capabilities and more, providing a rich and broad set of security features, required by the most demanding customers.

Setup and Configuration

Ease-of-use is very important for the setup and configuration of data centers or high performance clusters. Deployment of console servers is made easier for the manager with script support and a user interface that was designed with ease-of-use in mind. With the console server providing a separation of the command and control network from the in-band data network, the manager could also use the out-of-band network to request the configuration files from the central configuration file server on demand.

The In-Reach LX Series has received rave reviews for management interfaces. Administrators can choose from an easy to use GUI or an industry standard style Command Line Interface (CLI).

Centralized Maintenance and Support

Ease of upgrading and maintenance are key features to consider. There should be no requirement to upgrade any servers on the upgrade of a console server. Software upgrades should be accomplished via the network from a central server. Large scale deployment provisions together with the ability to configure complex events and resulting actions for each port will enhance management capabilities.

Device scalability is an important issue. For example, some devices can manage 256 nodes or more, while others can scale up to only 16 ports per device. Low-density devices can bring down the centralized management integrity, whereas high-density devices require a well-designed GUI to reduce keystrokes for node identification.

The LX Console Servers offer rich management capabilities, including a powerful clustering feature which automates configuration or software updates, scripting and GUI or CLI interfaces. The MRV Megavision Network Management System offers full SNMP GUI based management, and robust fault management capabilities.

Power Management

For many sites, the ability to remotely manage power is essential, from knowing when a power failure occurs, to reducing maintenance time, and increasing security. Instead of having a separate management interface, administrators can monitor and control power through the console server. Typical features include control over individual power outlets, logical grouping and control, current monitoring, and power up sequencing.

The MRV 5150 Power Control Series is available in a wide variety of port densities and packages, including 8 and 16 port models, 15, 20 or 30-Amp power input feeds, and various mounting choices.


Other functionality related factors to consider include the maximum number of sessions, broadcast capability, user interface design, ability to partition, error handling, ease of diagnostics, and concurrent monitoring of servers. Depending on the application, alarm management for power, temperature, humidity, or automated dry contacts could be essential.

Rack Space

Rack space optimization can affect costs significantly. For example, some devices are in a 1U form factor with 16 ports per device and can be 0U mounted (mounted on the side of a rack). Others have higher port density, but are in a 3U or larger form factor. Adopting large form factors for management devices can require extra racks.

All LX Series products are in 1U form factor or smaller. The power solutions in the MRV product set (see below) are offered in 1U and 0U form factors.

KVM Switches - Another Choice

KVM (Keyboard Video Mouse) switches enable server networks to have a single point of access to all servers. If the servers need video capabilities, a KVM switch is a suitable option. A server can be connected to a KVM switch input port via a KVM cable, which consists of keyboard, mouse, and video cables. Three types of KVM switches include:

  • Analog KVM switch
  • Digital KVM switch, which can cascade with traditional analog KVM switches
  • Advanced KVM switch using Cat-5 cables
  • Analog KVM Switches

While KVM switches are transparent to the BIOS/OS of a server, there is a disadvantage in that accessibility is limited to the length of the KVM cable. There is a lack of support for remote access methods.

Digital KVM Switches

Digital KVM switches are derived from analog KVM switches to overcome the accessibility requirement. The digital KVM is also called KVM over IP. A digital KVM switch has a CPU, an embedded operating system, some RAM for the OS, some NVRAM for settings/configuration, one network port, and many KVM ports. Digital KVM switches also support secured connections over the network. KVM over IP solutions are frequently plagued by performance problems.

Advanced KVM Switch using Cat-5 Cable

The advanced KVM switch uses a Cat-5 cable and a dongle, which are paired to replace a traditional thick KVM cable. The advanced KVM switch connects to a digital console box, and the box connects to a keyboard, a monitor, and a mouse directly. The digital console box, which replaces a management computer, serves as the management node. Rack space is a limited resource for a data center or cluster implementation. The Cat-5 cable and dongle pair help to optimize cabling management and rack space. For high-density configurations, the dongle size can be an inconvenience. If improperly installed, the dongle can also cause potential cooling problems.

Comparing Management Devices

Although the easiest to implement, the drawback to analog KVM switches is the lack of remote accessibility. When frequently adding and moving racks, cable management also becomes a concern.

Console servers require more effort than the advanced KVM switch for setting up BIOS and configuring the OS on all servers. Both satisfy the need for remote accessibility. The console server can manage text mode applications smoothly. However, when the system requires remote high resolution/ frame-rate graphics screen monitoring, then the digital KVM switch may be the proper choice. Even when the KVM solution has remote accessability, it may not provide the required out-of-band management. For example, Microsoft has provided Emergency Management Services as part of The Microsoft® Windows® Server 2003 family, providing native support for server operations and management over a serial port. Using EMS, servers can be managed remotely even when the operating system is not running properly or when the GUI interface is non-responsive. All of the considerations of security, ease-of-use, rack space, scalability and maintainability need to be considered when making the choice for out-of-band management systems.

Selecting the proper management tool for monitoring can facilitate all the management tasks, reduce downtime, and make the installation easy to use, maintain, and expand.

Future Trends for Out-Of-Band Management

As the use of commodity server platforms continues to grow, out-of-band management becomes essential. Scalability, manageability, and usability of out-of-band management devices become critical to the data center's success. The out-of-band management trend is to provide flexible reconfiguration, support compressed highbandwidth remote management capability, and move from add-on devices to integrated solutions to reduce the installation and management effort.

Several vendors that include HP, Dell, Intel and NEC support a specification called the Intelligent Platform Management Interface (IPMI). It defines common interfaces to hardware that is used to manage the physical characteristics of systems, such as temperature, voltage, fans, power supplies and chassis. While only used by a small percentage of customers today, the usage will increase over time.

MRV is working with vendors to develop next generation systems that bring the best of console server out-ofband management together with new requirements for out-of-band management, and welcomes opportunities to discuss these topics.


The MRV In-Reach solution enhances data center infrastructure by offering console server management with out-of-band communication, plus remote power control. It offers high-densities, ease-of-use and a well-designed graphical user interface with the best security in the industry. MRV LX Series console server offerings have a record of excellent performance with an outstanding customer support organization to stand behind its products. MRV works with its customers to bring the best solutions to each customer's management requirements.