Simple Network Management Protocol

System and Network Management Network Management : ability to monitor, control and plan the resources and components of computer system and networks network management is a problem created by computer! Goal of network management : keep networks up and running

Goal of Management Keeping Network Running Maintaining Network performance Reducing the Cost of Ownership

Architecture of Management Components : Manager and agent Manager : monitor and control the agents Agents: softwarte componentes residing in mangaed devices responds to requests from manager Network Management Protocol protocol used to communicated between Manager and agents

agent Manager Network Management Protocol

SNMP Easy-to-implement network management tool fot TCP/IP suite of protocols SNMP : a collection of specification actual protocols definition of manage information other related components

SNMP model SNMP components manager, agent and protocol SNMP Manager Simple Network Management Protocol

SNMP agent Software process that respons to SNMP protocol resides in networks equipments such as hub, router, bridges or workstaions Two basic roles monitoring controlling Hardware Components Software SNMP agent request response

Components of SNMP agent Prortocol Engine request response Management Information Base SNMP agent Protocol engine : processing request from SNMP managers receving request decoding servicing the request sending response Management Information Base (MIB) : collection of managed objects each object is a data variable standardized across system of a particular class

MIB objects Each managed object has a unique identifier, called an MIB object identifier used for referencing an MIB object ALL SNMP standards agents are required to support a standard set of managed objects every MIB objects has an MIB definition that defines the managed object MIB definitions are created using Abstract Syntax Notation One (ASN.1) ASN.1 is a machine-independence data description (initially developed for use in OSI) Only a subset of ASN.1 is used for SNMP Rules for writing MIB definitions using ASN.1 are defined in Structure of Management Information (SMI)

SNMP protocol

SNMP operations Get Request Get Next Request Get Response Set Request Trap

Variable binding Each SNMP variable binding consists of a variable called obkject identifier (OID) and associated value Object identifier Object value

MIB Tree Structure for reference OID

ASN.1 Notation syscontact OID = 1.3.6.1.2.1.1.4 sysContact OBJECT-TYPE SYNTAX DisplayString (SIZE (0..255)) ACCESS read-write STATUS mandatory DESCRIPTION "The textual identification of the contact person for this managed node, together with information on how to contact this person." ::= { system 4 } syscontact OID = 1.3.6.1.2.1.1.4 = iso.org.dod.internet.mgmt.mib-2.system.sycontact

Basic Encoding Rule Each field is encoded by BER Tag : variable type Length Contents Tag : variable type Length : length of contents Contents : encoded data

Encoding example get request 1.3.6.1.2.1.1.1.0 30 27 sequence of 39 bytes 02 01 00 version 1 04 06 73 23 6E 6D 70 21 6 bytes of community string = #SNMP! A0 1B request of 25 bytes 02 04 23 41 3D 3E id =591478078 02 01 00 error status =0 02 01 00 error index=0 30 0E sequence of length 14 bytes 30 0C sequence of length of 12 bytes 06 08 2B 06 01 02 01 01 01 01 00 object id of 8 bytes 1.3.6.1.2.1.1.1.0 05 00 null of 0 bytes Version community str. PDU type request ID error status error index variable binding