Notes On Chapter Thirty-Nine -- Network Management (SNMP)

• 39.1 Introduction
  
  
  • Software that network administrators use to monitor and control network devices.
  
  
• 39.2 Managing An Internet
  
  
  • The manager works to detect and correct problems.
    
    
  • The networks often have large numbers of devices and software components of widely differing type and manufacture.
  
  
• 39.3 The Danger Of Hidden Failures
  
  
  • Devices and protocols may partially mask and compensate for intermittent failure (e.g. as TCP does by retransmitting).
    
    
  • Nonetheless failures in network hardware and software tend to reduce effective network bandwidth and increase delay.
  
  
• 39.4 Network Management Software
  
  
  • Use net management software to monitor and control:
    • hosts
    • routers
    • switches
    • bridges
    
    
  • Determine status
    
    
  • Obtain statistics (example: number of dropped or scrambled packets)
    
    
  • Control devices (examples: change routes, or configure a network interface)
  
  
• 39.5 Clients, Servers, Managers, And Agents
  
  
  • Much software used for network management follows the familiar client/server paradigm, however in this context client = manager and server = agent.
    
    
  • The agents run on the devices that are monitored.
  
  
• 39.6 Simple Network Management Protocol
  
  
  • The current standard protocol for internet management is Simple Network Management Protocol, version 3 (SNMPv3).
    
    
  • SNMP defines:
    • the format of requests that a manager sends to an agent,
    • the format of replies that an agent returns,
    • the exact meaning of each possible request and reply,
    • the language, Abstract Syntax Notation.1 (ASN.1) in which SNMP messages are to be encoded.
    
    
• 39.7 Fetch-Store Paradigm
  
  
  • SNMP implements a fetch-store paradigm under which fetch commands are used to monitor devices and store commands are used to control devices.
  
  
• 39.8 The MIB And Object Names
  
  
  • The set of all objects that SNMP can access is known as a Management Information Base (MIB). Specification of MIB variables is separate from SNMP.
  
  
• 39.9 The Variety of MIB Variables
  
  
  • Separate specification of MIB variables provides flexibility for new variable definitions as needed.
    
    
  • There are MIB variables for UDP, TCP, IP, ARP, Ethernet, bridges, switches, and printers.
  
  
• 39.10 MIB Variables That Correspond To Arrays
  
  
• 39.11 Summary