Download Chapter 36 Network Management & SNMP

Chapter 36 Network
Management & SNMP
Network management

monitors network related hardware & software;
troubleshoot network problems
 Detects major failures
– eg. total hardware failure, bogus routing entry

intermittent failures difficult to detect and isolate
– Eg.a bad NIC card may lead to many retransmissions,
reducing available bandwidth to others

network management software runs at layer 7 of
the ISO 7-layer model
 client application program (manager) runs on
network management computer
 Server process (agent) listens on UDP port 161 on
network device
Simple Network
Management Protocol

defines format of manager requests and agent replies
 SNMP message is encoded using Abstract Syntax
Notation (ASN.1)
– Eg. to encode an integer, ASN.1 sends a pair of values: a
length L followed by L octets that contain the integer

SNMP uses fetch/store (get/set) paradigm
– manager retrieves data from agent or sets an objects within
the network device to a certain state

Eg. MRTG
Management Information
Base

the set of all objects SNMP can access
 each object (MIB variable) is uniquely represented
by a sequence of numbers corresponding to
sequence of names
– eg. 1.3.6.1.2.1.4.3 represents
iso.org.dod.internet.mgmt.mib.ip.ipInReceives

there are MIB variables for
– protocols such as UDP, TCP, IP, ARP
– hardware such as Ethernet, TokenRing, FDDI, bridge,
switch
– tables such as routing tables.