Computer Networking Chapter 9

Network Management9-1Chapter 9Network ManagementA note on the use of these ppt slides:We‟re making these slides freely available to all (faculty, students, readers). They‟re in PowerPoint form so you can add, modify, and delete slides (including this one) and slide content to suit your needs. They obviously represent a lotof work on our part. In return for use, we only ask the following:If you use these slides (e.g., in a class) in substantially unaltered form, that you mention their source (after all, we‟d like people to use our book!)If you post any slides in substantially unaltered form on a www site, that you note that they are adapted from (or perhaps identical to) our slides, and note our copyright of this material.Thanks and enjoy! JFK/KWRAll material copyright 1996-2007J.F Kurose and K.W. Ross, All Rights ReservedComputer Networking: A Top Down Approach ,4thedition. Jim Kurose, Keith RossAddison-Wesley, July 2007. Network Management9-2Chapter 9: Network ManagementChapter goals:introduction to network managementmotivationmajor componentsInternet network management frameworkMIB: management information baseSMI: data definition languageSNMP: protocol for network managementsecurity and administrationpresentation services: ASN.1Network Management9-3Chapter 9 outlineWhat is network management?Internet-standard management frameworkStructure of Management Information: SMIManagement Information Base: MIBSNMP Protocol Operations and Transport MappingsSecurity and AdministrationASN.1Network Management9-4What is network management?autonomous systems (aka “network”):100s or 1000s of interacting hardware/software componentsother complex systems requiring monitoring, control:jet airplanenuclear power plantothers?"Network managementincludes the deployment, integration and coordination of the hardware, software, and human elements to monitor, test, poll, configure, analyze, evaluate, and control the network and element resources to meet the real-time, operational performance, and Quality of Service requirements at a reasonable cost."Network Management9-5Infrastructure for network managementagentdataagentdataagentdataagentdatamanaged devicemanaged devicemanaged devicemanaged devicemanagingentitydatanetworkmanagementprotocoldefinitions:managed devicescontainmanaged objectswhose data is gathered into aManagement InformationBase (MIB)managing entityNetwork Management9-6Network Management standardsOSI CMIPCommon Management Information Protocoldesigned 1980’s: theunifying net management standardtoo slowly standardizedSNMP: Simple Network Management ProtocolInternet roots (SGMP)started simpledeployed, adopted rapidlygrowth: size, complexitycurrently: SNMP V3de factonetwork management standardNetwork Management9-7Chapter 9 outlineWhat is network management?Internet-standard management frameworkStructure of Management Information: SMIManagement Information Base: MIBSNMP Protocol Operations and Transport MappingsSecurity and AdministrationASN.1Network Management9-8SNMP overview: 4 key partsManagement information base (MIB):distributed information store of network management dataStructure of Management Information (SMI):data definition language for MIB objectsSNMP protocolconvey manager<->managed object info, commandssecurity, administration capabilitiesmajor addition in SNMPv3Network Management9-9SMI: data definition languagePurpose:syntax, semantics of management data well-defined, unambiguousbase data types: straightforward, boringOBJECT-TYPEdata type, status, semantics of managed objectMODULE-IDENTITYgroups related objects into MIB moduleBasic Data TypesINTEGERInteger32Unsigned32OCTET STRINGOBJECT IDENTIFIEDIPaddressCounter32Counter64Guage32Time TicksOpaqueNetwork Management9-10SNMP MIBOBJECT TYPE:OBJECT TYPE:OBJECT TYPE:objects specified via SMIOBJECT-TYPEconstructMIB module specified via SMI MODULE-IDENTITY(100 standardized MIBs, more vendor-specific)MODULENetwork Management9-11SMI: Object, module examplesOBJECT-TYPE:ipInDeliversMODULE-IDENTITY:ipMIBipInDelivers OBJECT TYPESYNTAX Counter32MAX-ACCESS read-onlySTATUS currentDESCRIPTION“The total number of input datagrams successfully delivered to IP user-protocols (including ICMP)”::= { ip 9}ipMIB MODULE-IDENTITYLAST-UPDATED “941101000Z”ORGANZATION “IETF SNPv2Working Group”CONTACT-INFO“ Keith McCloghrie……”DESCRIPTION“The MIB module for managing IPand ICMP implementations, butexcluding their management ofIP routes.”REVISION “019331000Z”………::= {mib-2 48}Network Management9-12MIB example: UDP moduleObject ID Name Type Comments1.3.6.1.2.1.7.1 UDPInDatagrams Counter32 total # datagrams deliveredat this node1.3.6.1.2.1.7.2 UDPNoPorts Counter32 # underliverable datagramsno app at portl1.3.6.1.2.1.7.3 UDInErrors Counter32 # undeliverable datagramsall other reasons1.3.6.1.2.1.7.4 UDPOutDatagrams Counter32 # datagrams sent1.3.6.1.2.1.7.5 udpTableSEQUENCEone entry for each portin use by app, gives port #and IP addressNetwork Management9-13SNMP Namingquestion:how to name every possible standard object (protocol, data, more..) in every possible network standard??answer:ISO Object Identifier tree:hierarchical naming of all objectseach branchpoint has name, number1.3.6.1.2.1.7.1ISOISO-ident. Org.US DoDInternetudpInDatagramsUDPMIB2managementNetwork Management9-14Check out www.alvestrand.no/harald/objectid/top.htmlOSI ObjectIdentifier TreeNetwork Management9-15SNMP protocolTwo ways to convey MIB info, commands:agentdataManaged devicemanagingentityresponseagentdataManaged devicemanagingentitytrap msgrequestrequest/response modetrap modeNetwork Management9-16SNMP protocol: message typesGetRequestGetNextRequestGetBulkRequestMgr-to-agent: “get me data”(instance,next in list, block)Message typeFunctionInformRequestMgr-to-Mgr: here’s MIB valueSetRequestMgr-to-agent: set MIB valueResponseAgent-to-mgr: value, response to RequestTrapAgent-to-mgr: inform managerof exceptional eventNetwork Management9-17SNMP protocol: message formatsNetwork Management9-18SNMP security and administrationencryption:DES-encrypt SNMP message authentication:compute, send MIC(m,k): compute hash (MIC) over message (m), secret shared key (k)protection against playback:use nonceview-based access controlSNMP entity maintains database of access rights, policies for various usersdatabase itself accessible as managed object!Network Management9-19Chapter 9 outlineWhat is network management?Internet-standard management frameworkStructure of Management Information: SMIManagement Information Base: MIBSNMP Protocol Operations and Transport MappingsSecurity and AdministrationThe presentation problem: ASN.1Network Management9-20The presentation problemQ:does perfect memory-to-memory copy solve “the communication problem”?A:not always!problem:different data format, storage conventionsstruct {char code;int x;} test;test.x = 256;test.code=„a‟a0000000100000011a0000001100000001test.codetest.xtest.codetest.xhost 1 formathost 2 formatNetwork Management9-21A real-life presentation problem:aging 60‟s hippie2007 teenagergrandmaNetwork Management9-22Presentation problem: potential solutions1.Sender learns receiver’s format. Sender translates into receiver’s format. Sender sends.–real-world analogy?–pros and cons?2.Sender sends. Receiver learns sender’s format. Receiver translate into receiver-local format–real-world-analogy–pros and cons?3.Sender translates host-independent format. Sends. Receiver translates to receiver-local format.–real-world analogy?–pros and cons?Network Management9-23Solving the presentation problem1.Translate local-host format to host-independent format2.Transmit data in host-independent format3.Translate host-independent format to remote-host formataging 60‟s hippie2007 teenagergrandmaNetwork Management9-24ASN.1: Abstract Syntax Notation 1ISO standardX.680used extensively in Internetlike eating vegetables, knowing this “good for you”!defined data types, object constructors like SMIBER: Basic Encoding Rulesspecify how ASN.1-defined data objects to be transmittedeach transmitted object has Type, Length, Value (TLV) encodingNetwork Management9-25TLV EncodingIdea:transmitted data is self-identifyingT:data type, one of ASN.1-defined typesL:length of data in bytesV:value of data, encoded according to ASN.1 standard1234569BooleanIntegerBitstringOctet stringNullObject IdentifierRealTag ValueTypeNetwork Management9-26TLVencoding:exampleValue, 5 octets (chars)Length, 5 bytesType=4, octet stringValue, 259Length, 2 bytesType=2, integerNetwork Management9-27Network Management: summarynetwork managementextremely important: 80% of network “cost”ASN.1 for data descriptionSNMP protocol as a tool for conveying informationNetwork management: more art than sciencewhat to measure/monitorhow to respond to failures?alarm correlation/filtering?