![0 231
IpAddress ::= [APPLICATION 0] IMPLICIT
OCTET STRING (SIZE (4))
Counter ::= [APPLICATION 1] IMPLICIT
INTEGER (0..4294967295)
Gauge ::= [APPLICATION 2] IMPLICIT
INTEGER (0..4294967295)
TimeTicks ::= [APPLICATION 3] IMPLICIT
INTEGER (0..4294967295)
Opaque ::= [APPLICATION 4] IMPLICIT
OCTET STRING
160.85.128.1
0 231
[ms]
0
0
10
1
20
2
A0 55 80 01](https://image.slidesharecdn.com/4-231006163404-1141ea8b/85/4-Net-Mgmt-pdf-28-320.jpg)
4. Net Mgmt.pdf
- 1. SNMP V 1.0
- 2. § The representation of objects and information relevant to their management § This information is usually communicated between agents and management processes § SMI (Structure of Management Information) defines the syntax and semantics of management information stored in MIB (Management Information Base) Example sysDescr: { system 1 } Syntax: OCTET STRING Definition: "A textual description of the entity. " Access: read-only Status: mandatory MIB r Contains information about objects r Organized by grouping of related objects r Defines relationship between objects r Agent MIB vs. Manager MIB m MIB Agent: local information m MIB Manager: info. on all network components Network Mgmt. Concepts Models & Lags Dr. Ibrahim Almerhag 2
- 3. § MDB physical database; e.g.. Oracle § Contains measured or administratively configured values of NEs § MIB virtual database; schema compiled into management software § Info necessary for processes to exchange info. (e.g., #ports/hub) § A NMS can automatically discover (periodic broadcast of PING messages) a managed object, such as a hub, when added to the network § Once detected, its information (e.g., address, number of ports, etc.) is added to MDB § MIB does not need to be updated if another hub from same vendor already exist Manager Managed objects MDB MIB r The NMS can identify a new added object only after the MIB schema of the new added object is compiled into manager MIB. Network Mgmt. Concepts Models & Lags Dr. Ibrahim Almerhag 4-3
- 4. § Both Internet and OSI define objects uniquely by a tree structure § Each managed object occupies a node in the tree underneath the root Root Level 1 Level 2 Level 3 Management Information Tree Managed Objects Standard organizations: define management of objects under them iso-itu 2 itu 0 iso 1 org 3 dod 6 internet 1 OSI Management Information Tree q Designation of objects: iso 1 org 1.3 dod 1.3.6 internet 1.3.6.1 4-4
- 5. object ID unique ID descriptor and name for the object syntax used to model the object access access privilege to a managed object (read-only, etc) status implementation requirements (e.g., optional or mandatory) definition textual description of the semantics of object type Network Mgmt. Concepts Models & Lags Dr. Ibrahim Almerhag 4-5
- 6. object class managed object attributes attributes visible at its boundary operations access operations that can be applied to it Behavior behavior exhibited by it in response to an operation Notifications notifications emitted by the object 4-6
- 7. Characteristics Example Object type PktCounter Syntax Counter Access Read-only Status Mandatory Description Counts number of packets Internet Perspective Characteristics Example Object class Packet Counter Attributes Single-valued Operations get, set Behavior Retrieves or resets values Notifications Generates notifications on new value OSI Perspective Packet Counter As Example of Managed Object Network Mgmt. Concepts Models & Lags Dr. Ibrahim Almerhag 7
- 8. § Configuration management § set and change network configuration and component parameters § Set up alarm thresholds § Fault management § Detection and isolation of failures in network § Trouble ticket administration § Performance management § Monitor performance of network § Security management § Authentication § Authorization § Encryption § Accounting management § Functional accounting of network usage OSI Functional Model Fault Management Configuration Management Performance Management Security Management Accounting Management 4-8
- 9. qOrganization Model qCommunication Model qInformation Model oStructure of Management Information (SMI) oManaged Objects oManagement Information Base (MIB) qSNMP Administrative Model qSNMP Protocol Specs
- 10. q Describes components of a network management system q Focuses on functions and infrastructure q Objects are network elements such as hubs, bridges, routers, etc. q Managed elements have a process running on them called an agent q Manager queries the agent, gets information, processes it and stores it in the MIB MIB agent agent Managed Objects Unmanaged Objects SNMP Manager A simplified hierarchical (2-tier) setup
- 11. Multiple managers, 1 agent § An agent responds to any management system that communicates with it using SNMP § A NMS provided by a vendor is in a better position to manage, monitor and configure all NEs coming from that same vendor Managed Object MIB Managed Objects SNMP Manager agent SNMP Manager Managers may have restricted access to managed objects
- 12. § Limiting the data that a manager wishes to obtain! § Remote Monitoring (RMON): acts as an agent and a manager § RMON gathers data from MO, analyses the data, and stores the data § Communicates the statistics to the manager Managed Object MIB Managed Objects SNMP Manager agent SNMP Manager Managers may have restricted access to managed objects RMON Probe 3-tier architecture
- 13. § Proxy server converts non-SNMP data from non-SNMP objects to SNMP compatible objects and messages Managed Object MIB Managed Objects SNMP Manager agent Proxy Server Wireless LAN unmanaged Objects
- 14. q Communicate mgnt information between network mgnt stations and managed elements q Goals: o Management functions maintained by agents are kept simple o Protocol flexibility (addition of new aspects of operation and management) o Transparency (should not be affected by the architecture of particular hosts and gateways) q Operation: 5 messages o get-request, get-next request, set-request o get-response, trap q SNMP messages are exchanged using UDP (connection less) transport protocol: ports 161 and 162
- 15. SNMP Manager Application Get-Response Get-Request GetNext-Request Set-Request Trap SNMP Manager SNMP Manager UDP IP DLC PHY SNMP Agent Application Get-Response Trap SNMP Agent SNMP agent UDP IP DLC PHY Physical Medium Manage- ment Data Get-Request GetNext-Request Set-Request Network or Internet Application Manages objects SNMP messages
- 16. Type Indication Cold-start of a system Agent is reinitializing itself since its Warm-start of a system configuration has changed Agent is reinitializing itself but its configuration has not changed Link down Link failure Link up Link restoral Failure of Authentication Request does not have proper authentication e.g., wrong SNMP community string EGP neighbor loss Exterior Gateway protocol neighbor gone Enterprise specific Specific to vendor implementing it
- 17. Type Format Cold-start of a system generic-trap INTEGER { coldStart (0), warmStart (1), linkDown (2), linkUp (3), authenticationFailure (4), egpNeighborLoss (5), enterpriseSpecific (6) } Warm-start of a system Link down Link up Failure of Authentication EGP neighbor loss Enterprise specific
- 18. q RFC 1155: Structure of Management Information q A common representation for data between both manager and agent q Defines the syntax (using ASN.1) to describe management information o Data types and o Rules used to define managed objects in a MIB q Generic objects and private (vendor specific) objects conforming to SMI rules (RFC 1155) can be managed by SNMP
- 19. q Objects have: object types and object instances q SMI is concerned with types and not instances q Object type § Name (unique descriptor and object identifier) § Syntax (ASN.1) § Encoding (BER) Object Object Instance Object Type Encoding: BER Syntax: ASN.1 Name: OBJECT IDENTIFIER Managed Object : Type and Instance
- 20. A hub with IP 172.16.46.3 is an instance of the object A hub is an object type 172.16.46.1 Backbone Network Hub 1 172.16.46.2 Hub 2 172.16.46.3 Router 1 172.17.252.1 Router 2 NMS 192.168.252.110 A Managed LAN Network Object Object Instance Object Type Encoding: BER Syntax: ASN.1 Name: OBJECT IDENTIFIER Managed Object : Type and Instance
- 21. Object Object Instance 3 Object Type Encoding: BER Syntax: ASN.1 Name: OBJECT IDENTIFIER Managed Object : Type with Multiple Instances Object Instance 2 Object Instance 1 Title: System Information: 172.16.46.2 Name or IP Address: 172.16.46.2 System Name : System Description : 3Com LinkBuilder FMS, SW version:3.02 System Contact : System Location : System Object ID : .iso.org.dod.internet.private.enterprises.43.1.8.5 System Up Time : (2475380437) 286 days, 12:03:24.37 System Information on 172.16.46.2 Hub Title: System Information: 172.16.46.3 Name or IP Address: 172.16.46.3 System Name : System Description : 3Com LinkBuilder FMS, SW version:3.12 System Contact : System Location : System Object ID : .iso.org.dod.internet.private.enterprises.43.1.8.5 System Up Time : (3146735182) 364 days,4:55:51.82 System Information on 172.16.46.3 Hub
- 22. § Each managed object is associated with an identifier (OBJECT IDENTIFIER) § Identifiers are used to name objects and they are unique for managed objects § identifier is a sequence of integers root ccitt(0) iso(1) joint-iso- ccitt(2) org(3) dod(6) internet(1) private(4) mgmt(2) experimental(3) enterprise(1) mib-2(1) internet OBJECT IDENTIFIER ::= { iso(1) org(3) dod(6) 1 } ::= {1 3 6 1 } ::= {iso standard dod internet} Name of managed object
- 23. mgmt (2) directory (1) experimental (3) private (4) Internet {1 3 6 1} Reserved for future use Used for objects defined in IAB-approved documents To identify objects used in Internet experiments Used heavily by commercial vendors Sub-nodes under Internet
- 24. mgmt (2) directory (1) experimental (3) private (4) Internet {1 3 6 1} mib-2 (1) system (1) interfaces (2) at (3) ip (4) icmp (5) snmp (11) transmission (10) cmot (9) egp (8) udp (7) tcp (6)
- 25. mgmt (2) directory (1) experimental (3) private (4) Internet {1 3 6 1} enterprises (1) hp (11) cisco (9) 3Com (43) Cabletron (52)
- 26. SNMP ASN. 1 Data Type Tag Structure Number Class Private Context specific Application universal Constructor or Structured Defined or Application Simple or Primitive
- 27. § Subtype: § INTEGER (0..255) § OCTET STRING (SIZE 0..255) § OCTET STRING (SIZE 8) error-status INTEGER { noError(0) tooBig(1) genErr(5) authorizationError(16) } r Special case of INTEGER data type (enumeration): Data Type Comments INTEGER Subtype INTEGER (n1..nN) Special case: Enumerated INTEGER type OCTET STRING 8-bit bytes binary and textual data Subtypes can be specified by either range or fixed OBJECT IDENTIFIER Object position in MIB NULL Placeholder
- 28. 0 231 IpAddress ::= [APPLICATION 0] IMPLICIT OCTET STRING (SIZE (4)) Counter ::= [APPLICATION 1] IMPLICIT INTEGER (0..4294967295) Gauge ::= [APPLICATION 2] IMPLICIT INTEGER (0..4294967295) TimeTicks ::= [APPLICATION 3] IMPLICIT INTEGER (0..4294967295) Opaque ::= [APPLICATION 4] IMPLICIT OCTET STRING 160.85.128.1 0 231 [ms] 0 0 10 1 20 2 A0 55 80 01
- 29. q SEQUENCE,SEQUENCE OF q SET and SET OF of ASN.1 are not included in SNMP-based management q Used to build lists and tables SEQUENCE {<type1>, <type2>,….., <typeN>} Object OBJECT IDENTIFIER ObjectSyntax 1 ipAdEntAddr {ipAddrEntry 1} IpAddress 2 ipAdEntIfIndex {ipAddrEntry 2} INTEGER 3 ipAdEntNetMask {ipAddrEntry 3} IpAddress 4 ipAdEntBcastAddr {ipAddrEntry 4} INTEGER 5 ipAdEntReasmMaxSize {ipAddrEntry 5} INTEGER 6 ipAddrEntry {ipAddrTable 1} SEQUENCE Managed objects Their location in the MIB Their data types
- 30. List: IpAddrEntry ::= SEQUENCE { ipAdEntAddr IpAddress ipAdEntIfIndex INTEGER ipAdEntNetMask IpAddress ipAdEntBcastAddr INTEGER ipAdEntReasmMaxSize INTEGER (0..65535) } Managed Object IpAddrEntry as a list Object Name OBJECT IDENTIFIER Syntax 7 ipAddrTable {ip 20} SEQUENCE OF Table: ipAddrTable ::= SEQUENCE OF IpAddrEntry Managed Object ipAddrTable as a table ipAddrTable is made up of instances of IpAddrEntry object
- 31. q Basic Encoding Rules, BER q Data Types and Tags q Encoding of Object Identifiers: Packs the first two integers into a single sub-identifier Type Tag OBJECT IDENTIFIER UNIVERSAL 6 SEQUENCE UNIVERSAL 16 IpAddress APPLICATION 0 Counter APPLICATION 1 Gauge APPLICATION 2 TimeTicks APPLICATION 3 Opaque APPLICATION 4
- 32. 0 Z = 40·X + Y X Y 43 0 6 0 1 0 4 0 1 06 05 2B 06 01 04 01 enterprise OBJECT IDENTIFIER ::={iso(1) org(3) dod(6) internet(1) private(4) 1}