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Lecture 13 Network Management

Lecture 13 Network Management. Outline. Network management concepts Internet-standard management framework (SNMP) Structure of Management Information: SMI Management Information Base: MIB SNMP Protocol Operations and Transport Mappings Security and Administration

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Lecture 13 Network Management

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  1. Lecture 13 Network Management Khaled Mahbub, IICT, BUET, 2008

  2. Outline • Network management concepts • Internet-standard management framework (SNMP) • Structure of Management Information: SMI • Management Information Base: MIB • SNMP Protocol Operations and Transport Mappings • Security and Administration • Abstract Syntax Notation One (ASN.1) Khaled Mahbub, IICT, BUET, 2008

  3. Network Management • autonomous systems (aka “network”): 100s or 1000s of interacting hardware/software components • "Network management includes 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." • More specifically network management comprises of: • Performance management: quantify, measure, report, analyze and control the performance (e.g., utilization, throughput) of different network components. • Fault management: log, detect, and respond to fault conditions in the network. • Configuration management: track which devices are on the managed network and the hardware and software configurations of these devices. • Accounting management:specify, log, and control user and device access to network resources. • Security management: control access to network resources according to some well-defined policy. Khaled Mahbub, IICT, BUET, 2008

  4. managing entity data managed device data data data data network management protocol managed device agent agent agent agent managed device managed device Infrastructure for Network Management • definitions: managing entity is an application that controls the collection, processing, analysis, and/or display of network management information. managed deviceis a piece of network equipment, e.g. host, router (including its software) that contains managed objects e.g. interface card,whose data is gathered into a Management Information Base (MIB) network management protocolruns between the managing entity and the managed devices to query the status of managed devices and take actions in these devices. Khaled Mahbub, IICT, BUET, 2008

  5. Network Management standards OSI CMIP • Common Management Information Protocol • designed 1980’s: the unifying net management standard • too slowly standardized SNMP: Simple Network Management Protocol • Internet roots (SGMP) • started simple • deployed, adopted rapidly • growth: size, complexity • currently: SNMP V3 • de facto network management standard Khaled Mahbub, IICT, BUET, 2008

  6. Outline • Network management concepts • Internet-standard management framework (SNMP) • Structure of Management Information: SMI • Management Information Base: MIB • SNMP Protocol Operations and Transport Mappings • Security and Administration • Abstract Syntax Notation One (ASN.1) Khaled Mahbub, IICT, BUET, 2008

  7. SNMP overview: 4 key parts • Management information base (MIB): • distributed information store of network management data. Management information is represented as a collection of managed objects. A MIB object might be a counter, such as the number of IP datagrams discarded at a router due to errors in an IP datagram header or the number of carrier sense errors in an Ethernet interface, • Structure of Management Information (SMI): • data definition language for MIB objects • SNMP protocol • convey manager<->managed object information, commands • security, administration capabilities • major addition in SNMPv3 Khaled Mahbub, IICT, BUET, 2008

  8. Purpose: syntax, semantics of management data well-defined, unambiguous base data types: INTEGER, Integer32, Unsigned32, OCTET STRING, OBJECT IDENTIFIED, IP address, Counter32, Counter64, Guage32, Time Ticks OBJECT-TYPE used to specify the data type, status, and semantics of a managed object. The OBJECT-TYPE construct has four clauses. The SYNTAX clause specifies the basic data type associated with the object. The MAX-ACCESS clause specifies whether the managed object can be read, written, created, or have its value included in a notification. The STATUS clause indicates whether object definition is current and valid, obsolete or deprecated. The DESCRIPTION clause contains a human-readable textual definition of the object; MODULE-IDENTITY groups related objects into MIB module SMI: Data Definition Language Khaled Mahbub, IICT, BUET, 2008

  9. SMI: Data Definition Language • NOTIFICATION-TYPE • is used to specify information regarding "InformationRequest" messages generated by an agent, or a managing entity. This information includes a textual DESCRIPTION of when such messages are to be sent, as well as list of values to be included in the message generated. • MODULE-COMPLIANCE • defines the set of managed objects within a module that an agent must implement. • AGENT-CAPABILITIES • specifies the capabilities of agents with respect to object and event notification definitions. Khaled Mahbub, IICT, BUET, 2008

  10. MODULE SNMP MIB 100 standardized MIBs, even more vendor-specific are defined, e.g. [RFC 2011] specifies the MIB module that defines managed objects for managing implementations of the Internet Protocol (IP) and its associated Internet Control Message Protocol (ICMP). [RFC 2012] specifies the MIB module for TCP and [RFC 2013] specifies the MIB module for UDP. MIB module specified via SMI MODULE-IDENTITY OBJECT TYPE: OBJECT TYPE: OBJECT TYPE: objects specified via SMI OBJECT-TYPE construct Khaled Mahbub, IICT, BUET, 2008

  11. OBJECT-TYPE: ipInDelivers ipInDelivers OBJECT TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION “The total number of input datagrams successfully delivered to IP user- protocols (including ICMP)” ::= { ip 9} SMI: Object, Module Examples ipInDeliversobject type definition (from [RFC 2011]) defines a 32-bit counter which keeps track of the number of IP datagrams that were received at the managed node ipMIB module definition for management of the IP protocol: MODULE-IDENTITY: ipMIB ipMIB MODULE-IDENTITY LAST-UPDATED “941101000Z” ORGANZATION “IETF SNPv2 Working Group” CONTACT-INFO “ Keith McCloghrie ……” DESCRIPTION “The MIB module for managing IP and ICMP implementations, but excluding their management of IP routes.” REVISION “019331000Z” ……… ::= {mib-2 48} Khaled Mahbub, IICT, BUET, 2008

  12. SNMP Naming question: 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 branch point has name, number 1.3.6.1.2.1.7.1 udpInDatagrams UDP MIB2 management ISO ISO-ident. Org. US DoD Internet Khaled Mahbub, IICT, BUET, 2008

  13. OSI Object Identifier Tree Khaled Mahbub, IICT, BUET, 2008

  14. MIB Example: UDP Module Khaled Mahbub, IICT, BUET, 2008

  15. request managing entity managing entity data data trap msg response Managed device Managed device agent agent SNMP Protocol Two ways to convey MIB information and commands: request/response mode: used to query (retrieve) or modify (set) MIB object values associated with a managed device. trap mode: used to notify a managing entity of an exceptional situation that has resulted in changes to MIB object values. Khaled Mahbub, IICT, BUET, 2008

  16. Function Message type GetRequest GetNextRequest GetBulkRequest Mgr-to-agent: “get me data” (instance,next in list, block) InformRequest Mgr-to-Mgr: here’s MIB value SetRequest Mgr-to-agent: set MIB value Agent-to-mgr: value, response to Request Response Agent-to-mgr: inform manager of exceptional event Trap SNMP Protocol: Message Types Khaled Mahbub, IICT, BUET, 2008

  17. SNMP Protocol: Message Formats Khaled Mahbub, IICT, BUET, 2008

  18. SNMP Protocol: Message Formats Khaled Mahbub, IICT, BUET, 2008

  19. SNMP Applications • Typically a SNMP applicationsconsist of two parts: • managing entity includes • a command generator: generates the GetRequest, GetNextRequest, GetBulkRequest and SetRequest PDUs • notification receiver: receive and process Trap PDUs • proxy forwarder: forwards request, notification, and response PDUs. • agent in managed device includes • a command responder: receives, processes and replies to received GetRequest, GetNextRequest, GetBulkRequest and SetRequest PDUs. • notification originator: generates Trap PDUs. Khaled Mahbub, IICT, BUET, 2008

  20. SNMP Engine and Application Khaled Mahbub, IICT, BUET, 2008

  21. SNMP Security and Administration • encryption: DES-encrypt SNMP message • authentication: compute, send MIC(m,k): compute hash (Message Integrity Code: MIC) over message (m), and 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! Khaled Mahbub, IICT, BUET, 2008

  22. Outline • Network management concepts • Internet-standard management framework (SNMP) • Structure of Management Information: SMI • Management Information Base: MIB • SNMP Protocol Operations and Transport Mappings • Security and Administration • Abstract Syntax Notation One (ASN.1) Khaled Mahbub, IICT, BUET, 2008

  23. a 00000011 00000001 a 00000001 00000011 The Presentation Problem Q: does perfect memory-to-memory copy solve “the communication problem”? A: not always! struct { char code; int x; } test; test.x = 259; test.code=‘a’ test.code test.x test.code test.x host 2 format host 1 format 259 in decimal is equivalent to binary 1 00000011 problem: different data format, storage conventions Khaled Mahbub, IICT, BUET, 2008

  24. Presentation Problem: Potential Solutions 1. Sender learns receiver’s format. Sender translates into receiver’s format. Sender sends. 2. Sender sends. Receiver learns sender’s format. Receiver translate into receiver-local format 3. Sender translates host-independent format. Sends. Receiver translates to receiver-local format. Khaled Mahbub, IICT, BUET, 2008

  25. Solving the Presentation Problem 1. Translate local-host format to host-independent format 2. Transmit data in host-independent format 3. Translate host-independent format to remote-host format Khaled Mahbub, IICT, BUET, 2008

  26. ASN.1: Abstract Syntax Notation One • ISO standard X.680 • used extensively in Internet • 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) encoding Khaled Mahbub, IICT, BUET, 2008

  27. TLV Encoding Idea: 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 standard Tag ValueType Boolean Integer Bitstring Octet string Null Object Identifier Real 1 2 3 4 5 6 9 Khaled Mahbub, IICT, BUET, 2008

  28. Value, 259 Length, 2 bytes Type=2, integer Value, 5 octets (chars) Length, 5 bytes Type=4, octet string TLV Encoding: Example Khaled Mahbub, IICT, BUET, 2008

  29. Reading Material • Chapter 8 – text3 (Kurose) • Chapter 25 – text1 (Stevens) Khaled Mahbub, IICT, BUET, 2008

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