Network Management

1
Network Management

• SNMP
• Minimodule 2, 2006-03-03

By Ole Krog Thomsen TDC
2
Simple Network Management Protocol (SNMP)

• Management Framework
• a data definition language,
• definitions of management information (the
  Management Information Base, or MIB),
• a protocol definition, and
• security and administration.

3
SNMP Architecture

• several (potentially many) nodes, each with an
  SNMP entity containing command responder and
  notification originator applications, which have
  access to manage-ment instrumentation
  (traditionally called agents)
• at least one SNMP entity containing command
  generator and/or notification receiver
  applications (traditionally called a manager)
  and,
• a management protocol used to convey management
  information between the SNMP entities.

4
SNMP Architecture
5
SNMP
Management
Documents
RFC 1067
RFC 1065
RFC 1066
SMI
MIB I
RFC 1098
RFC 1155
RFC 1156
SNMPv1
STD 16
RFC 1157
Concise SMI
SNMPv1
STD 15
RFC 1212
Traps
STD 16
RFC 1215
RFC 1158
MIB II
RFC 1213
STD 17
RFC 1448
RFC 1449
RFC 1442
RFC 1443
RFC 1444
SNMPv2
SNMPv2
SMIv2 Txt
SMIv2
Protocol Ops
SMIv2
Transport Map.
Conventions
Conformances
RFC 1902
RFC 1905/3416
RFC 1906/3417
RFC 1903
RFC 1904
MIB II for
SNMPv2
RFC 1907/3418
Figure 4.4 SNMP Document Evolution
6
SNMPv1 documents

• RFC 1155 Structure and Identification of
  Management Information for TCP/IP-based Internets
  (SMI)
• RFC 1157 A Simple Network Management Protocol
  (SNMP)
• RFC 1212 Concise MIB Definitions
• RFC 1213 Management Information Base for Network
  Management of TCP/IP-based internets MIB-II
• RFC 1215 A Convention for Defining Traps for use
  with the SNMP

7
SNMPv2 documents

• RCF 1901 Introduction to Community-based SNMPv2
  (SNMPv2c)
• RFC 1902 Structure of Management Information for
  Version 2 of the Simple Network Management
  Protocol (SNMPv2)
• RFC 1903 Textual Conventions for Version 2 of the
  Simple Network Management Protocol (SNMPv2)
• RFC 1904 Conformance Statements for Version 2 of
  the Simple Network Management Protocol (SNMPv2)
• RFC 1905/3416 Protocol Operations for Version 2
  of the Simple Network Management Protocol
  (SNMPv2)
• RFC 1906/3417 Transport Mappings for Version 2 of
  the Simple Network Management Protocol (SNMPv2)
• RFC 1907/3418 Management Information Base for
  Version 2 of the Simple Network Management
  Protocol (SNMPv2)
• RFC 1908 Coexistence between Version 1 and
  Version 2 of the Internet-standard
  Network Management Framework
• RFC 1909 An Administrative Infrastructure for
  SNMPv2 (SNMPv2u)
• RFC 1910 User-based Security Model for SNMPv2
  (SNMPv2u)

8
SNMPv3 documents

• RFC 2570/3419, "Introduction to Version 3 of the
  Internet-standard Network Management Framework",
• RFC 2571/3411, "An Architecture for Describing
  SNMP Management Frameworks
• RFC 2572/3412, "Message Processing and
  Dispatching for the Simple Network Management
  Protocol (SNMP)
• RFC 2573/3413, "SNMP Applications
• RFC 2574/3414, "The User-Based Security Model for
  Version 3 of the Simple Network Management
  Protocol (SNMPv3)
• RFC 2575/3415, "View-based Access Control Model
  for the Simple Network Management Protocol
  (SNMP)

9
SNMP Communication Architecture
10
SNMP Messages

• Get-Request
• Get-Next-Request
• Set-Request
• Get-Response
• Trap
• Generic trap
• Specific trap
• Time stamp

11
Administrative Model

• Based on community profile and policy
• SNMP Entities
• SNMP application entities
• Reside in management stations and network
  elements
• Manager and agent
• SNMP protocol entities
• Communication processes (PDU handlers)
• Peer processes that support application entities

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Protocol Data
15
ASN.1 history

• 1984 X.409 (encoding rules included)
• 1986 ISO 8824 / ISO 8825
• 1988 X.208 / X.209 (Subtypes, Object Identifier)
• 1990 ISO 8824 / ISO 8824 rev (? X.208 / X.209)
• 1994 X.680-serie / X.690-serie

16
ASN.1 Standards (1990 version)

• CCITT Rec. X.208 (1988) ISO/IEC 88241990,
  Specification of abstract syntax notation one
  (ASN.1)
• CCITT Rec. X.209 (1988) ISO/IEC 88251990,
  Specification of basic encoding rules for
  abstract syntax notation one (ASN.1)

17
ASN.1 Standards (1994 version)

• ITU-T Rec. X.680 (1994) ISO/IEC 8824-11995,
  Abstract Syntax Notation One (ASN.1)
  Specification of basic notation
• ITU-T Rec. X.681 (1994) ISO/IEC 8824-21995,
  Abstract Syntax Notation One (ASN.1)
  Information object specification
• ITU-T Rec. X.682 (1994) ISO/IEC 8824-31995,
  Abstract Syntax Notation One (ASN.1) Constraint
  specification
• ITU-T Rec. X.683 (1994) ISO/IEC 8824-41995,
  Abstract Syntax Notation One (ASN.1)
  Parameterization of ASN.1 specifications
• ITU-T Rec. X.690 (1994) ISO/IEC 8825-11995,
  ASN.1 encoding rules Specification of Basic
  Encoding Rules (BER), Canonical Encoding Rules
  (CER) and Distinguished Encoding Rules (DER)
• ITU-T Rec. X.691 (1995) ISO/IEC 8825-21996,
  ASN.1 encoding rules Specification of Packed
  Encoding Rules (PER)

18
ASN.1 Types

• Abstract Data Type Definition Language
• Type
• a named set of values
• Simple type
• a type defined by directly specifying the set of
  its values
• Structured type
• a type defined by reference to one or more other
  types

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ASN.1 Simple types

• BOOLEAN
• INTEGER ()
• BIT STRING
• OCTET STRING ()
• NULL ()
• OBJECT IDENTIFIER ()
• REAL
• ENUMERATED
• Only those marked with () are used by SNMPv1

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ASN.1 Structured types

• SEQUENCE ()
• SEQUENCE OF ()
• SET
• SET OF
• CHOICE
• Only those marked with () are used by SNMPv1

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ASN.1 TLV - encoding
Definite encoding
Indefinite encoding
22
ASN.1 encoding
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Object Identifier tree
24
Company specific OIDs
internet 1 3 6 1
private (4)
enterprises (1)
3com (43)
ericsson (193)
cisco (9)
siemens (231)
25
OBJECT IDENTIFIER examples

• xatmInfoModel OBJECT IDENTIFIER ccitt(0)
  identified-organization(4) etsi(0) xcoop(1996)
  informationModel(0)
• jamesInfoModel OBJECT IDENTIFIER itu-t(0)
  network-operator(3) teleDanmark(2383) james(19)
  wp42-tc2(0)
• ftam-as OBJECT IDENTIFIER iso standard
  ftam(8571) abstract-syntax (1)
• umf-mo OBJECT IDENTIFIER joint-iso-ccitt
  ms(9) function(2) part10(10) managedObjectClass(3)
  
• internet OBJECT IDENTIFIER iso org(3)
  dod(6) 1
• mgmt OBJECT IDENTIFIER internet 2
• mib-2 OBJECT IDENTIFIER mgmt 1
• system OBJECT IDENTIFIER mib-2 1
• ip OBJECT IDENTIFIER mib-2 4

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ASN.1 encoding of Object Identifier

• Each sub-identifier is encoded as a sequence of
  7-bit binary codes, the first are marked with bit
  8 1 and the last with bit 8 0.

The first sub-identifier is calculated as
(S1 40) S2
27
MIBs

• MANAGEMENT INFORMATION BASES
• CONTAIN THE MANAGED OBJECTS (VARIABLES)
• THAT REPRESENT THE RESOURCES OF A SYSTEM
• AND WHICH MAY BE MONITORED AND MODIFIED BY A
  (REMOTE) MANAGER
• TO CONTROL THE BEHAVIOUR OF THAT SYSTEM

28
MIB DEFINITION AND MIB INSTANCE

• MIB DEFINITIONS SHOULD BE KNOWN BY
• THE IMPLEMENTORS OF THE MANAGED SYSTEM
• THE MANAGER
• THE MIB IS INSTANTIATED WITHIN THE MANAGED SYSTEM

29
OBJECT-TYPE (rfc1212)

• OBJECT-TYPE MACRO
• BEGIN
• TYPE NOTATION
• -- must
  conform to
• --
  RFC1155's ObjectSyntax
• "SYNTAX"
  type(ObjectSyntax)
• "ACCESS" Access
• "STATUS" Status
• DescrPart
• ReferPart
• IndexPart
• DefValPart
• VALUE NOTATION value (VALUE
  ObjectName)

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sysLocation Object (rfc1213)

• sysLocation OBJECT-TYPE
• SYNTAX DisplayString (SIZE
  (0..255))
• ACCESS read-write
• STATUS mandatory
• DESCRIPTION
• "The physical location of
  this node (e.g.,
• telephone closet, 3rd
  floor')."
• system 6

31
Tabular Representation of Aggregate Object
32
Tabular Representation of Aggregate Object
33
Lexicographic sorting
A B T E 1.1 1.2 2.1 2.2 3.1 3.2 Z
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ifTable Object (rfc1213)

• ifTable OBJECT-TYPE
• SYNTAX SEQUENCE OF IfEntry
• ACCESS not-accessible
• STATUS mandatory
• DESCRIPTION
• "A list of interface
  entries. The number of
• entries is given by the
  value of ifNumber."
• interfaces 2

36
ifEntry Object (rfc1213)

• ifEntry OBJECT-TYPE
• SYNTAX IfEntry
• ACCESS not-accessible
• STATUS mandatory
• DESCRIPTION
• "An interface entry
  containing objects at the
• subnetwork layer and below
  for a particular
• interface."
• INDEX ifIndex
• ifTable 1

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ifEntry Object (rfc1213)

• IfEntry SEQUENCE
• ifIndex INTEGER,
• ifDescr DisplayString,
• ifType INTEGER,
• ifMtu INTEGER,
• ifSpeed Gauge,
• ifPhysAddress PhysAddress,
• ifAdminStatus INTEGER,
• ifOperStatus INTEGER,
• ifLastChange TimeTicks,
• ifInOctets Counter,
• ifInUcastPkts Counter,
• ifInNUcastPkts Counter,
• ifInDiscards Counter,
• ifInErrors Counter,
• ifInUnknownProtos Counter,
• ifOutOctets Counter,
• ifOutUcastPkts Counter,
• ifOutNUcastPkts Counter,

38
ifDescr Object (rfc1213)

• ifDescr OBJECT-TYPE
• SYNTAX DisplayString (SIZE
  (0..255))
• ACCESS read-only
• STATUS mandatory
• DESCRIPTION
• "A textual string containing
  information about the
• interface. This string should
  include the name of
• the manufacturer, the product
  name and the version of the hardware
  interface."
• ifEntry 2

39
SNMP Message

• Message SEQUENCE
• version --
  version-1 for this RFC
• INTEGER
• version-1(0)
• ,
• community --
  community name
• OCTET STRING,
• data -- e.g.,
  PDUs if trivial
• ANY --
  authentication is being used

40
SNMP PDUs

• PDUs
• CHOICE
• get-request GetRequest-P
  DU,
• get-next-request GetNext
  Request-PDU,
• get-response GetResponse
  -PDU,
• set-request SetRequest-P
  DU,
• trap Trap-PDU

41
SNMP Supporting Definitions

• RequestID INTEGER
• ErrorStatus INTEGER
• noError(0),
• tooBig(1),
• noSuchName(2),
• badValue(3),
• readOnly(4)
• genErr(5)
• ErrorIndex INTEGER
• VarBind SEQUENCE
• name ObjectName,
• value ObjectSyntax
• VarBindList SEQUENCE OF VarBind

42
GET/SET PDU Types

• GetRequest-PDU 0 IMPLICIT SEQUENCE
• request-id RequestID,
• error-status ErrorStatus, -- always 0
  
• error-index ErrorIndex, -- always 0
  
• variable-bindings VarBindList
• GetNextRequest-PDU 1 IMPLICIT SEQUENCE
  
• GetResponse-PDU 2 IMPLICIT SEQUENCE
• SetRequest-PDU 3 IMPLICIT SEQUENCE