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Lecture 13

Network Management

Khaled Mahbub, IICT, BUET, 2008 ICT 6621 : Advanced Networking

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 ICT 6621 : Advanced Networking

Network Management

• autonomous systems (aka “network”): hardware/software components 100s or 1000s of interacting • " 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 ICT 6621 : Advanced Networking

Infrastructure for Network Management • definitions:

managing entity data

network management protocol

agent data managed device Khaled Mahbub, IICT, BUET, 2008 agent agent data managed device data managed device

managing entity

is an application that controls the collection, processing, analysis, and/or display of network management information.

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)

agent data managed device

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 Networking

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 ICT 6621 : Advanced Networking

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 ICT 6621 : Advanced Networking

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 ICT 6621 : Advanced Networking

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 Khaled Mahbub, IICT, BUET, 2008 ICT 6621 : Advanced Networking

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 ICT 6621 : Advanced Networking

SNMP MIB

MIB module specified via SMI MODULE-IDENTITY MODULE OBJECT TYPE: objects specified via SMI OBJECT-TYPE construct Khaled Mahbub, IICT, BUET, 2008 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 Networking

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 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} 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 ICT 6621 : Advanced Networking

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 1.3.6.1.2.1.7.1

udpInDatagrams UDP MIB2 management Khaled Mahbub, IICT, BUET, 2008 ICT 6621 : Advanced Networking

OSI Object Identifier Tree

Khaled Mahbub, IICT, BUET, 2008 ICT 6621 : Advanced Networking

MIB Example: UDP Module

Object ID 1.3.6.1.2.1.7.1

1.3.6.1.2.1.7.2

1.3.6.1.2.1.7.3

1.3.6.1.2.1.7.4

1.3.6.1.2.1.7.5

Name UDPInDatagrams UDPNoPorts UDInErrors UDPOutDatagrams udpTable Khaled Mahbub, IICT, BUET, 2008 Type Counter32 Counter32 Comments total number of UDP datagrams delivered to UDP users total number of received UDP datagrams for which there was no application at the destination port Counter32 Counter32 SEQUENCE of UdpEentry number of received UDP datagrams that could not be delivered for reasons other than the lack of an application at the destination port total number of UDP datagrams sent from this entity 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 Networking

SNMP Protocol

Two ways to convey MIB information and commands: managing entity request response agent data Managed device request/response mode: used to query (retrieve) or modify (set) MIB object values associated with a managed device.

managing entity trap msg agent data 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 ICT 6621 : Advanced Networking

SNMP Protocol: Message Types

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

SNMP Protocol: Message Formats

Khaled Mahbub, IICT, BUET, 2008 ICT 6621 : Advanced Networking

SNMP Protocol: Message Formats

Khaled Mahbub, IICT, BUET, 2008 ICT 6621 : Advanced Networking

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.

Khaled Mahbub, IICT, BUET, 2008 ICT 6621 : Advanced Networking

SNMP Engine and Application

Khaled Mahbub, IICT, BUET, 2008 ICT 6621 : Advanced Networking

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 ICT 6621 : Advanced Networking

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 ICT 6621 : Advanced Networking

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

a 00000001 00000011 host 1 format 259 in decimal is equivalent to binary 1 00000011 test.code

test.x

a 00000011 00000001 host 2 format problem: different data format, storage conventions Khaled Mahbub, IICT, BUET, 2008 ICT 6621 : Advanced Networking

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 ICT 6621 : Advanced Networking

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 ICT 6621 : Advanced Networking

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 ICT 6621 : Advanced Networking

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 Value 1 2 3 4 5 6 9 Type Boolean Integer Bitstring Octet string Null Object Identifier Real Khaled Mahbub, IICT, BUET, 2008 ICT 6621 : Advanced Networking

TLV Encoding: Example

V alue, 259 L ength, 2 bytes T ype=2, integer V alue, 5 octets (chars) L ength, 5 bytes T ype=4, octet string Khaled Mahbub, IICT, BUET, 2008 ICT 6621 : Advanced Networking

Reading Material

• Chapter 8 – text3 (Kurose) • Chapter 25 – text1 (Stevens) Khaled Mahbub, IICT, BUET, 2008 ICT 6621 : Advanced Networking