Transcription of Lecture 11: Introduction to Network Management
1 1 Prof. Shervin ShirmohammadiCEG 418511-1 Lecture 11: Introduction toNetwork Management Prof. Shervin ShirmohammadiSITE, University of OttawaProf. Shervin ShirmohammadiCEG 418511-2 Objective Manage a Network by managing its components: routers, bridges, gateways, applications, .. Managing: Observingstatus Changingsettings Networks are indispensable More complexity makes failure more likely We need automatic Network Management tools Standards required to allow multi-vendor networks interoperability2 Prof. Shervin ShirmohammadiCEG 418511-3 Computer NetworksProf. Shervin ShirmohammadiCEG 418511-4 Network Management Systems Collection of tools for Network Management Single operatorinterface Powerful, user friendly command set Performing most or all Management tasks Minimal amount of separate equipment use existing equipment View entire Network as unified architecture Active elements provide regular feedback3 Prof.
2 Shervin ShirmohammadiCEG 418511-5 Key Elements Management station or manager Agent Management information base (MIB) Network Management protocolProf. Shervin ShirmohammadiCEG 418511-6 Management Station Stand alone system or part of shared system Interface for humannetwork manager Set of Management applications Data query and analysis Operational commands Fault recovery Interface to monitor and control Network Translate manager s requirements into monitoringand controlof remote elements Database of Network Management information extracted from managed entities4 Prof.
3 Shervin ShirmohammadiCEG 418511-7 Management Agent Hosts, bridges, hubs, routers, .., equipped with agentsoftware Allows them to be managedfrom Management station Respond to requests for information Respond to requests for action Asynchronously supply unsolicited Shervin ShirmohammadiCEG 418511-8 Management Information Base (MIB) Representationof Network resources as objects Each object a variablerepresenting one aspect of managed object. Typically defined in MIB is a collection of access points at agent for Management of station. Objects standardized across classes of system Bridge, router etc.
4 There are pre-defined standard MIBsfor many existing networking devices (ATM switches, Ethernet ports, IP routers, ..) Shervin ShirmohammadiCEG 418511-9 MIB ExampleIP-MIB DEFINITIONS ::= BEGINIMPORTSMODULE-IDENTITY, OBJECT-TYPE, Integer32,Counter32, IpAddress, mib-2 FROM SNMPv2-SMIPhysAddressFROM SNMPv2-TCMODULE-COMPLIANCE,OBJECT-GROUP FROM SNMPv2-CONF;..ipDefaultTTL OBJECT-TYPESYNTAX INTEGER ( )MAX-ACCESS read-writeSTATUS currentDESCRIPTION"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.
5 "::= { ip 2 }ipInReceives OBJECT-TYPESYNTAX Counter32 MAX-ACCESS read-onlySTATUS currentDESCRIPTION"The total number of input datagrams received from interfaces, including those received in error."::= { ip 3 }Prof. Shervin ShirmohammadiCEG 418511-10 MIB Viewer 6 Prof. Shervin ShirmohammadiCEG 418511-11 Management Layout May be centralizedin a simple Network May be distributedin large, complex networks Multiple Management servers Each manages pool of agents Management may be delegated to intermediate managerProf. Shervin ShirmohammadiCEG 418511-12 Example Configuration7 Prof.
6 Shervin ShirmohammadiCEG 418511-13 Network Management Protocol Protocol for exchange of informationbetween 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/IPProf. Shervin ShirmohammadiCEG 418511-14 SNMP IETF standard SNMP v2 1993, revised 1996 RFC 1901-1908 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 security8 Prof.
7 Shervin ShirmohammadiCEG 418511-15 SNMPv1 ConfigurationProf. Shervin ShirmohammadiCEG 418511-16 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 withGetResponse Agent may issue trapmessage in response to event that affects MIB and underlying managed Port 1629 Prof. Shervin ShirmohammadiCEG 418511-17 Role of SNMP v1 Prof. Shervin ShirmohammadiCEG 418511-18 Object Names and SMI Object Treeiso-itu2iso1itu0org3dod6internet1pri vate4enterprise1 IBM2 Private type identifier for In a MIB there is an identifier for each occurrence of an OBJECT IDENTIFIER ::= {ISO(1) ORG(3) DOD(6) INTERNET(1)}10 Prof.
8 Shervin ShirmohammadiCEG 418511-19mgmt(2)directory(1)experimental (3)private(4)Internet{1 3 6 1}mib-2(1)Figure Internet MIB-II Groupsystem (1)interfaces (2)at (3)ip (4)icmp (5)snmp (11)transmission (10)cmot (9)egp (8)udp (7)tcp (6)SNMP MIB-2 {mgmt 1}Prof. Shervin ShirmohammadiCEG 418511-20IP Group 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 addressesipRoutingDiscards (23)ip(mib-2 4)ipForwarding (1)ipDefaultTTL (2)ipInReceives (3)ipInHdrErrors (4)ipInAddrErrors (5)ipForwDatagrams (6)ipInUnknownProtos (7)ipInDiscards (8)ipInDelivers (9)ipOutRequests(10)ipNetToMediaTable (22)ipRouteTable (21)ipAddrTable (20)ipFragCreates (19)ipFragFails (18)ipFragOKs (17)ipReasmFails (16)ipReasmOKs (15)
9 IpReasmReqds (14)ipOutDiscards (11)ipReasmTimeout (13)ipOutNoRoutes (12)Figure IP Group11 Prof. Shervin ShirmohammadiCEG 418511-21 EntityOIDD escription (brief)ipAddrTableip 20 Table of IP addressesipAddrEntryIpAddrTable 1 One of the entries in the IP addresstableipAdEntAddrIpAddrEntry 1 The IP address to which this entry'saddressing information pertainsipAdEntIfIndexIpAddrEntry 2 Index value of the entry, same asifIndexipAdEntNetMaskIpAddrEntry 3 Subnet mask for the IP address ofthe entryipAdEntBcastAddrIpAddrEntry 4 Broadcast address indicator bitipAdEntReasmMaxSize IpAddrEntry 5 Largest IP datagram that can bereassembled on this interfaceipAdEntAddr (1)
10 IpAddrEntry(ipAddrTable 1)ipAdEntReasmMaxSize (5)ipAdEntBcastAddr (4)Figure IP Address TableipAddrTable(ip 20)ipAdEntIfIndex (2)ipAdEntNetMask(3)Legend: INDEX in boldIP Address TableProf. Shervin ShirmohammadiCEG 418511-22 Example Say a Router has this standard table BoldColumn indicates index. To get the maximum reassembly sizeat interface3, the manager would send the SNMP command:get_request( ) To which the agent on the router replies:get_response( )status IpAdEntAddr IpAdEntIfIndex IpAdEntBcastAddr IpAdEntReasmMaxSize 1 1 0 12000 1 3 1 12000 1 2 0 10000 1 4 0 15000 12 Prof.
