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Network and computer equipment use various methods for management. Common methods use the Console port, TCP/IP and SNMP protocols. All equipment support at least one of these methods and in many cases all three. MRV Communications is leading provider of management solutions and has products in all three areas.
In-band Management (TCP/IP and SNMP)
Most networking equipment such as switches, routers, network appliances and servers include a TCP/IP stack that is directly connected to the network to which it's providing some type of service (ie. routing packets, serving web pages, etc...). Among the packet processing functions, these devices recognize management packets that are addressed to the device itself.
The simplest management packet is an ICMP Ping request, where the receiving device simply replies with an ICMP Ping Reply. More useful protocols such as TELNET, SSH and HTTP are often supported by network devices, where a terminal or web page interface is given to the user.
SNMP is a standard management protocol commonly found on networking devices. It has industry standard MIBs (Management Information Base) that include objects such as system uptime, interface statistics and TCP/IP statistics. SNMP also provides for vendor specific extensions called private MIBs. The central managing device in SNMP is called an NMS (Network Management System) and is usually responsible for managing every TCP/IP capable device in the network. With standard and private MIBs, 100s or 1000s of variables and counters per device can be management by an NMS.
An important management feature of SNMP is the ability to send traps. When an event occurs on a device that needs the Network Manager's attention, a trap message is sent to the NMS. A common trap is a link up/down trap to indicate to the Network Manager that a link on a device has changed state and probably needs investigation. The NMS logs the receipt of the trap and alerts the Network Manager.
SNMP is a poll and response protocol, where the NMS polls the network device. RMON (Remote Monitoring) is a management protocol that's event driven. When the event occurs, a trap is sent to the NMS. Unlike normal SNMP Traps that are pre-defined, devices that support RMON allow the Network Manager to choose the event he wishes to see traps for, example: if a counter exceeds 1000, send a trap.
MRV Communications' MegaVision Pro(r) is a full-featured, SNMP-based Network Management System (NMS). It provides comprehensive management and control for all MRV Communications manageable products
MegaVision Pro combines complete end-to-end network viewing and performance monitoring with robust configuration and fault management features. In addition, MegaVision Pro automatically detects and monitors any SNMP or TCP/IP compliant device from any vendor.
All configuration and monitoring is performed via MegaVision Pro's feature-rich graphic user-interface (GUI). The MegaVision Pro Server operates on all major OS platforms, including: Win95, Win98, WinNT, Win2000 and WinXP.
MegaVision Pro may be used to monitor the performance of Layer 7 network services, helping network administrators pinpoint potential bottlenecks. It also offers Layer 2 and Layer 3 management capabilities including support for policies, filters, VLANs, and routing. Other MegaVision Pro features include support for RMON groups 1, 2, 3, and 9, and north-bound interfaces for OSS (operations support systems) integration (TL1, XML, SQL and SNMP interfaces). A standard SQL database is used to keep network management information and history alarm logs
Out-of-Band Management, Console Management
Most networking equipment includes an EIA RS-232C interface. This interface connects to a terminal device to provide serial console access to a device. This access is character based and is presented to the user as a CLI (Command Line Interface). This interface is used for initial configuration and, for some devices, the primary means to configure and manage the device. Even when alternative management methods are supported, during times of network failures, mis-configurations and troubleshooting, the serial console interface is usually the only interface that can be used to remedy the problem.
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.
The term "out-of-band" management is used, since the devices' network ports are not used for management. This also adds a level of security by not using the network. Instead, each device has its own physical connection to the console server. The Network Manager then connects to the Console Server either local, remotely over a secure modem or over the network. In the latter case, the network may be either a private managed network separate from the main network or the main network itself. In the case of connecting to the main network, the Console Server only has one or two network connection making troubleshooting much easier than numerous network connections of the managed devices. For access to the console server over either network, TELNET or SSH is used.
In-Band vs. Out-Band Management
Both In-Band and Out-Band management methods have their pros and cons. In-Band takes advantage of TCP/IP Interface and SNMP agents commonly found on networking equipment. With SNMP, MRV's MegaVision Pro includes easy to use GUI support, Trap reception / logging and RMON support. It can be used to manage any TCP/IP or SNMP device from any vendor.
The main disadvantage is the "in-band" nature of TCP/IP and SNMP. Troubleshooting difficulties arise, since the network interfaces of the managed devices need to be up in order manage the device. Another disadvantage is that not all network equipment support management with TCP/IP or SNMP. Sometimes the only management option is to use serial console-ports.
Conversely, Console Servers don't require a network interface to be functional or even exist on the device. It uses the EIA RS-232C interface. The main disadvantage is that CLIs vary from vendor to vendor and even device to device. They also require commands to be entered manually, if scripting doesn't exist. MRV's MegaVision Pro has an easy to use GUI Interface and support for common MIBs and TCP/IP management.
MRV Communication is a leading provider in both In-Band and Out-of-Band management. Both MegaVision Pro and the In-Reach series of Console Servers can work together to provide best of both worlds.
Consider the case where a Network Manager manages a group of routers. One router is experiencing a problem with the router protocol OSPF on particular router. The router closest to the NMS will send an SNMP trap indicating an OSPF neighbor state change and the Network Manager will be immediately informed of the situation. Since OSPF routing is required to be functional to reach the faulty router, router configuration changes aren't possible over the network. Instead, the Network Manager connects to the faulty router's console port though the Console Server and makes the necessary changes to fix the situation.
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