Lecture 11: Introduction to Network Management

Size: px

Start display at page:

Download "Lecture 11: Introduction to Network Management"

Eleanore Parker
6 years ago
Views:

1 Lecture 11: Introduction to Network Management Prof. Shervin Shirmohammadi SITE, University of Ottawa Prof. Shervin Shirmohammadi CEG Objective Manage a network by managing its components: routers, bridges, gateways, applications, Managing: Observing status Changing settings Networks are indispensable More complexity makes failure more likely We need automatic network management tools Standards required to allow multi-vendor networks interoperability Prof. Shervin Shirmohammadi CEG

2 Computer Networks Prof. Shervin Shirmohammadi CEG Network Management Systems Collection of tools for network management Single operator interface Powerful, user friendly command set Performing most or all management tasks Minimal amount of separate equipment i.e. use existing equipment View entire network as unified architecture Active elements provide regular feedback Prof. Shervin Shirmohammadi CEG

3 Management station or manager Agent Management information base (MIB) Network management protocol Key Elements Prof. Shervin Shirmohammadi CEG Management Station Stand alone system or part of shared system Interface for human network manager Set of management applications Data query and analysis Operational commands Fault recovery Interface to monitor and control network Translate manager s requirements into monitoring and control of remote elements Database of network management information extracted from managed entities Prof. Shervin Shirmohammadi CEG

4 Management Agent Hosts, bridges, hubs, routers,, equipped with agent software Allows them to be managed from management station Respond to requests for information Respond to requests for action Asynchronously supply unsolicited information. Prof. Shervin Shirmohammadi CEG Management Information Base (MIB) Representation of network resources as objects Each object a variable representing one aspect of managed object. Typically defined in ASN.1 MIB is a collection of access points at agent for management of station. Objects standardized across classes of system Bridge, router etc. There are pre-defined standard MIBs for many existing networking devices (ATM switches, Ethernet ports, IP routers, ) Prof. Shervin Shirmohammadi CEG

MIB Example IP-MIB DEFINITIONS ::= BEGIN IMPORTS MODULE-IDENTITY, OBJECT-TYPE, Integer32, Counter32, IpAddress, mib-2 FROM SNMPv2-SMI PhysAddress FROM SNMPv2-TC MODULE-COMPLIANCE, OBJECT-GROUP FROM

5 MIB Example IP-MIB DEFINITIONS ::= BEGIN IMPORTS MODULE-IDENTITY, OBJECT-TYPE, Integer32, Counter32, IpAddress, mib-2 FROM SNMPv2-SMI PhysAddress FROM SNMPv2-TC MODULE-COMPLIANCE, OBJECT-GROUP FROM SNMPv2-CONF;... ipdefaultttl OBJECT-TYPE SYNTAX INTEGER (1..255) MAX-ACCESS read-write STATUS current DESCRIPTION "The default value inserted into the Time-To-Live field of the IP header of datagrams originated at this entity, whenever a TTL value is not supplied by the transport layer protocol." ::= { ip 2 } ipinreceives OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "The total number of input datagrams received from interfaces, including those received in error." ::= { ip 3 } Prof. Shervin Shirmohammadi CEG MIB Viewer Prof. Shervin Shirmohammadi CEG

6 Management Layout May be centralized in a simple network May be distributed in large, complex networks Multiple management servers Each manages pool of agents Management may be delegated to intermediate manager Prof. Shervin Shirmohammadi CEG Example Configuration Prof. Shervin Shirmohammadi CEG

7 Network Management Protocol Protocol for exchange of information between management station and agent. TCP/IP uses Simple Network Management Protocol (SNMP) not very many capabilities but easy to implement most commonly used management protocol OSI uses Common Management Information Protocol (CMIP) Lots of capabilities but complicated to implement Used by large telecommunications companies SNMPv2 (enhanced SNMP) for OSI and TCP/IP Prof. Shervin Shirmohammadi CEG SNMP IETF standard SNMP v2 1993, revised 1996 RFC Stand alone management stations and bridges, routers workstations etc supplied with agents Defines limited, easily implemented MIB of scalar variables and two dimensional tables Capabilities: Get Retrieve information Set Configure settings Trap Unsolicited information Problems: Limited functionality Lack of security Prof. Shervin Shirmohammadi CEG

8 SNMPv1 Configuration Prof. Shervin Shirmohammadi CEG SNMP Architecture Application-level protocol Typically implemented as part of TCP/IP protocol suite Runs over UDP What if messages are lost? From a management station, three types of SNMP messages are issued GetRequest, GetNextRequest, and SetRequest Port 161 Agent replies with GetResponse Agent may issue trap message in response to event that affects MIB and underlying managed Port 162 Prof. Shervin Shirmohammadi CEG

Role of SNMP v1 Prof. Shervin Shirmohammadi CEG 4185 11-17 Object Names and SMI Object Tree itu 0 iso 1 org 3 dod 6 iso-itu 2 In a MIB there is an identifier for each occurrence of an object.

9 Role of SNMP v1 Prof. Shervin Shirmohammadi CEG Object Names and SMI Object Tree itu 0 iso 1 org 3 dod 6 iso-itu 2 In a MIB there is an identifier for each occurrence of an object. internet OBJECT IDENTIFIER ::= {ISO(1) ORG(3) DOD(6) INTERNET(1)} internet 1 private 4 enterprise 1 IBM 2 Private type identifier for IBM Prof. Shervin Shirmohammadi CEG

10 SNMP MIB-2 {mgmt 1} Internet { } directory (1) mgmt (2) experimental (3) private (4) mib-2 (1) system (1) interfaces (2) at (3) ip (4) icmp (5) tcp (6) snmp (11) transmission (10) cmot (9) egp (8) udp (7) Figure 4.26 Internet MIB-II Group Prof. Shervin Shirmohammadi CEG This group has various information on the parameters of the IP protocol. ipforwarding: Gateway(1) and Router(2) IP Address Table contains table of IP addresses IP Route Table contains an entry for each route IP Network-to-Media Table is address translation table mapping IP addresses to physical addresses IP Group ipforwarding (1) ipdefaultttl (2) ipinreceives (3) ipinhdrerrors (4) ipinaddrerrors (5) ipforwdatagrams (6) ipinunknownprotos (7) ipindiscards (8) ipindelivers (9) ipoutrequests(10) ip (mib-2 4) iproutingdiscards (23) ipnettomediatable (22) iproutetable (21) ipaddrtable (20) ipfragcreates (19) ipfragfails (18) ipfragoks (17) ipreasmfails (16) ipreasmoks (15) ipreasmreqds (14) ipoutdiscards (11) ipreasmtimeout (13) ipoutnoroutes (12) Figure 4.29 IP Group Prof. Shervin Shirmohammadi CEG

11 ipaddrtable (ip 20) ipaddrentry (ipaddrtable 1) IP Address Table ipadentaddr (1) ipadentifindex (2) Legend: INDEX in bold ipadentnetmask (3) ipadentreasmmaxsize (5) ipadentbcastaddr (4) Figure 4.30 IP Address Table Entity OID Description (brief) ipaddrtable ip 20 Table of IP addresses ipaddrentry IpAddrTable 1 One of the entries in the IP address table ipadentaddr IpAddrEntry 1 The IP address to which this entry's addressing information pertains ipadentifindex IpAddrEntry 2 Index value of the entry, same as ifindex ipadentnetmask IpAddrEntry 3 Subnet mask for the IP address of the entry ipadentbcastaddr IpAddrEntry 4 Broadcast address indicator bit ipadentreasmmaxsize IpAddrEntry 5 Largest IP datagram that can be reassembled on this interface Prof. Shervin Shirmohammadi CEG Example Say a Router has this standard table status IpAdEntAddr IpAdEntIfIndex IpAdEntBcastAddr IpAdEntReasmMaxSize Bold Column indicates index. To get the maximum reassembly size at interface 3, the manager would send the SNMP command: get_request( ) To which the agent on the router replies: get_response( =12000) Prof. Shervin Shirmohammadi CEG

12 Structure of Management Information (SMI) Defines general framework with which MIB is defined and constructed Language for defining management information Based on ASN.1 Identifies data types Identifies how resources are represented and named Encourages simplicity and extensibility Scalars and two dimensional arrays of scalars (tables) only Prof. Shervin Shirmohammadi CEG SMI Definition from RFC1155 EXPORTS identifies the objects that any other module could import RFC1155-SMI DEFINITIONS ::= BEGIN EXPORTS -- EVERYTHING internet, directory, mgmt, experimental, private, enterprises, OBJECT-TYPE, ObjectName, ObjectSyntax, SimpleSyntax, ApplicationSyntax, NetworkAddress, IpAddress, Counter, Gauge, TimeTicks, Opaque; -- the path to the root internet OBJECT IDENTIFIER ::= { iso org(3) dod(6) 1 } directory OBJECT IDENTIFIER ::= { internet 1 } mgmt OBJECT IDENTIFIER ::= { internet 2 } experimental OBJECT IDENTIFIER ::= { internet 3 } private OBJECT IDENTIFIER ::= { internet 4 } enterprises OBJECT IDENTIFIER ::= { private 1 } Prof. Shervin Shirmohammadi CEG

13 SMI Definition from RFC1155 ( ) -- definition of object types OBJECT-TYPE MACRO ::= BEGIN TYPE NOTATION ::= "SYNTAX" type (TYPE ObjectSyntax) "ACCESS" Access "STATUS" Status VALUE NOTATION ::= value (VALUE ObjectName) Access ::= "read-only" "read-write" "write-only" "not-accessible" Status ::= "mandatory" "optional" "obsolete" END application-wide types NetworkAddress ::= CHOICE { internet IpAddress } IpAddress ::= [APPLICATION 0] -- in network-byte order IMPLICIT OCTET STRING (SIZE (4)) Counter ::= [APPLICATION 1] IMPLICIT INTEGER ( ).. Prof. Shervin Shirmohammadi CEG SNMPv2 SNMPv1 was developed as an interim solution to an eventual adoption of OSI. This never came about: OSI was not as widely adopted as originally hoped. We got stuck with SNMPv1, which was not a comprehensive solution. SNMPv2, released in 1996, was basically major revisions added to SNMP. Prof. Shervin Shirmohammadi CEG

Major Changes Bulk data transfer Manager-to-manager message Enhancements to SMI: SMIv2 Module definitions: MODULE-IDENTITY macro (information) Object definitions: OBJECT-IDENTITY macro (info about

14 Major Changes Bulk data transfer Manager-to-manager message Enhancements to SMI: SMIv2 Module definitions: MODULE-IDENTITY macro (information) Object definitions: OBJECT-IDENTITY macro (info about OID) Trap definitions: NOTIFICATION-TYPE macro Textual conventions (Help define new data types) Conformance statements (Compatibility to standard) Row creation and deletion in table MIB enhancements (added security & snmpv2) Transport mappings Security features, originally to be in SNMPv2, moved to SNMPv3 Hence, SNMPv2, like SNMPv1, uses a community-based administrative framework Prof. Shervin Shirmohammadi CEG SNMPv2 PDU Exchange of messages Outer message header deals with security (outside the scope of SNMPv2) Seven types of PDU (InformRequest used between managers) Prof. Shervin Shirmohammadi CEG

15 Key Features: SNMPv3 Modularization of documentation and architecture Enables the use of SNMPv1 and SNMPv2 with the newly developed SNMPv3. SNMP engine defined A model for the processing of SNMP messages. New Security features Secure information to prevent tampering of data Access control to determine proper access to MIB. Prof. Shervin Shirmohammadi CEG SNMPv3 Architecture An SNMP entity is a node with an SNMP management element either an agent or manager or both The architecture of an SNMP entity consists of the elements of the entity and the names associated with it. There are three names associated with an entity Entities: e.g. SNMP engine (snmpengineid) Identities: e.g. Principal and security name Management Information: Used when multiple objects are managed. E.g. Context engine SNMP entity SNMP Engine (identified by snmpengineid) Dispatcher Application(s) Command Generator Command Responder Message Processing Subsystem Security Subsystem Notification Receiver Notification Originator Access Control Subsystem Proxy Forwarder Subsystem Prof. Shervin Shirmohammadi CEG Figure 7.2 SNMPv3 Architecture Other 15

16 Telecommunications Management Network (TMN) There is Necessity for interoperability Need for management of more than just the network components Networks / subnetworks need to be managed Services - internal and external need management Business management needs to be addressed TMN joint effort by ITU-T and ISO Prof. Shervin Shirmohammadi CEG Operations System Refers to operations support system (OSS) E.g., Trunk is a logical connection between two switching nodes Periodic measurement of loss and S/N of all trunks Failing threshold set for QoS; failing trunks removed out of service before the customer complains Transmission Test System Trunk Test System Telecommunication Network Nodes Transmission Test System Voice Public Switch Transmission Links Public Switch Voice Figure 11.1 Operations System for Network Transmission Prof. Shervin Shirmohammadi CEG

17 OS: Telephone Switch Traffic Traffic monitored at switch Call blocking statistics obtained Traffic and call-blocking statistics provide data for planning Importance of Operations, administration, maintenance, and provisioning Traffic Measurement System Traffic Counter Data / Telecommunication Network Nodes Traffic Counter Router / Switch Transmission Links Router / Switch Prof. Shervin Shirmohammadi CEG Figure 11.2 Operations System for Traffic Measurement TMN in Data and Telecom Networks Logically separate networks NMS considered OS Telecommunications Management Network Operations System Operations System NMS Operations System Workstation Data Communication Network Switching System Transmission System Switching System Transmission System Switching System Voice Telecommunication Network Voice TMN: A Network of Operation Systems (OSs). Figure 11.3 TMN Relationship to Data and Telecommunication Network Prof. Shervin Shirmohammadi CEG

18 TMN Architecture Functional architecture: Functional modules or blocks Reference points between modules Physical architecture: Physical blocks Physical interfaces between the blocks Informational architecture: Information exchange between entities Object oriented TMN Architecture Functional Architecture Physical Architecture Informational Architecture Figure 11.6 TMN Architecture Prof. Shervin Shirmohammadi CEG Functional Architecture OSF: Functions performed by Operations systems E.g., NMS, testing, accounting, trouble tracking NEF: Functions needed to support network elements; network elements themselves are not part of TMN: e.g., NM agent, MIB, collision rate MF: Operations on the information between network elements; e.g. filtering, protocol conversion MF can be shared between multiple OSs; e.g. RMON WSF: Human-TMN activities interface; e.g., GUI QAF: Adapter function to accommodate non-tmn entities; e.g. proxy server, SNMP-to-CMIP TMN A Prof. Shervin Shirmohammadi CEG NEF TMN B q3 qx OSF x OSF q3 MF qx QAF q3 f OSF WSF Figure 11.7 TMN Functional Architecture MF Mediation Function NEF Network Element Function OSF Operations Systems Function QAF Q Adapter Function WSF Workstation Function 18

19 TMN Reference Point Function blocks connected by conceptual interfaces, called reference point Designated by lower case letters (upper case letter for physical interfaces) x: Interface between operations systems that belong to different domains; e.g., interface between two NMSs belonging to two different domains q3: Interface between two OSFs in the same domain qx: Interface between mediation function such as RMON and agent in the network element f: Interface to the workstation Function Block Reference Point Function Block Figure 11.8 TMN Reference Point Prof. Shervin Shirmohammadi CEG Management Service Architecture Network element: switches, routers, etc. Element management: manages the elements Network management: manages the network; e.g., bandwidth, performance, QoS, etc. Service management: manages services provided to customers. E.g., billing, order processing, complaints, trouble ticket. Business management: concerned with managing the operations: fiscal consideration, human resource needs, project management, customer satisfaction. Business Management Service Management Network Management Element Management Managed Network Element Prof. Shervin Shirmohammadi CEG q3 q3 q3 q3 Figure TMN Service Architecture 19

20 TMN Services & Functions TMN Management Services Business Management Service Management Network Management Element Management System Management Functional Areas Configuration Management Fault Management Performance Management Security Management Accounting Management DCF TMN Function Blocks OSF WSF NEF MF QAF System Management Functions Object Alarm Management Management TMN Functional Components NM Presentation Manager Function M-GET / GET-REQUEST M-SET / SET-REQUEST CMISE M-CREATE Remote Procedure Call ACSE ROSE Communication Transport Service (OSI Presentation Layer) Figure TMN Services and Functions Prof. Shervin Shirmohammadi CEG

Lecture 18: Network Management

Lecture 18: Network Management Prof. Shervin Shirmohammadi SITE, University of Ottawa Prof. Shervin Shirmohammadi CEG 4183 18-1 Objective Manage a network by managing its components: routers, bridges,