ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Lecture 13 Network Management

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 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)

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 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.

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Infrastructure for Network Management definitions: agent data agent data agent data agent data managed device managing entity data network management protocol managed device is 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) managing entity is an application that controls the collection, processing, analysis, and/or display of network management information. network management protocol runs between the managing entity and the managed devices to query the status of managed devices and take actions in these devices.

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 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

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 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)

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 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

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 SMI: Data Definition Language 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

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 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.

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 SNMP MIB objects specified via SMI OBJECT-TYPE construct MIB module specified via SMI MODULE-IDENTITY OBJECT TYPE: MODULE 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.

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 SMI: Object, Module Examples 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} MODULE-IDENTITY: ipMIB ipMIB MODULE-IDENTITY LAST-UPDATED “ Z” 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 “ Z” ……… ::= {mib-2 48} 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:

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 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 ISO ISO-ident. Org. US DoD Internet udpInDatagrams UDP MIB2 management

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 OSI Object Identifier Tree

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 MIB Example: UDP Module Object IDNameTypeComments UDPInDatagramsCounter32total number of UDP datagrams delivered to UDP users UDPNoPortsCounter32total number of received UDP datagrams for which there was no application at the destination port UDInErrorsCounter32number of received UDP datagrams that could not be delivered for reasons other than the lack of an application at the destination port UDPOutDatagramsCounter32total number of UDP datagrams sent from this entity udpTableSEQUENCE of UdpEentry a sequence of UdpEntry objects, one for each port that is currently open by an application, giving the IP address and the port number used by application

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 SNMP Protocol Two ways to convey MIB information and commands: agent data Managed device managing entity trap msg agent data Managed device managing entity response request 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.

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 SNMP Protocol: Message Types GetRequest GetNextRequest GetBulkRequest Mgr-to-agent: “get me data” (instance,next in list, block) Message type Function InformRequest Mgr-to-Mgr: here’s MIB value SetRequest Mgr-to-agent: set MIB value Response Agent-to-mgr: value, response to Request Trap Agent-to-mgr: inform manager of exceptional event

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 SNMP Protocol: Message Formats

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 SNMP Protocol: Message Formats

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 SNMP Applications Typically a SNMP applications consist 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.

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 SNMP Engine and Application

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 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!

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 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)

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 The Presentation Problem Q: does perfect memory-to-memory copy solve “the communication problem”? A: not always! problem: different data format, storage conventions struct { char code; int x; } test; test.x = 259; test.code=‘a’ a a test.code test.x test.code test.x host 1 format host 2 format 259 in decimal is equivalent to binary

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 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.

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 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

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 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

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 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 Boolean Integer Bitstring Octet string Null Object Identifier Real Tag Value Type

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 TLV Encoding: Example Value, 5 octets (chars) Length, 5 bytes Type=4, octet string Value, 259 Length, 2 bytes Type=2, integer

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Reading Material Chapter 8 – text3 (Kurose) Chapter 25 – text1 (Stevens)