Network Management 9-1/27

Poglavlje 9Upravljanje mrežom

Computer Networking: A Top Down Approach Featuring the Internet, 3rd edition. Jim Kurose, Keith RossAddison-Wesley, July 2004.

Network Management 9-2/27

Poglavlje 9: upravljanje mrežomCiljevi: Uvod

motivacija glavne komponente

Okvir upravljanja mrežama na Internet-u MIB: baza upravljačkih informacija SMI: data definition language SNMP: protokol za mrežni menadžment bezbednost i administracija

prezentacioni servisi: ASN.1

Network Management 9-3/27

Poglavlje 9 kratak pregled

Šta je mrežni menadžment? Okvir Internet-standardnog menadžmenta

Structure of Management Information: SMI Management Information Base: MIB SNMP Protocol Operations and Transport Mappings Bezbednost i administracija

Abstract Syntax Notation 1 - ASN.1

Network Management 9-4/27

Šta je mrežni menadžment?

autonomni sistemi (“mreže”): 100 ili 1000 međusobno povezanih hardversko/softverskih komponenti

različiti složeni sistemi zahtevaju monitoring, kontrolu: avioni nuklearne centrale drugi?

"Mrežni menadžment uključuje razvijanje, integraciju i koordinaciju hardvera, softvera i ljudi da bi nadgledali, testirali,ispitivali, konfigurisali, analizirali, razvijali i kontrolisali mrežui resurse, da bi ispunili u realnom vremenu performanse radai zahteve kvaliteta servisa sa razumnim troškovima"

Network Management 9-5/27

Infrastruktura za upravljanje mrežom

agent data

agent data

agent data

agent data

managed device

managed device

managed device

managed device

managingentity data

networkmanagement

protocol

definicije:

managed devices sadržemanaged objects čije podatke sakupljaju u

Management InformationBase (MIB)

managing entity

Network Management 9-6/27

Standardi mrežnog menadžmenta

OSI CMIP Common Management

Information Protocol projektovan 1980:

unificira net management standard

isuviše sporo standardizovan

SNMP: Simple Network Management Protocol

Internet korene (SGMP) startovan prosto razvijan, prilagođen

rapidno veličina, kompleksnost trenutno: SNMP V3 de facto standard za

mrežni menadžment

Network Management 9-7/27

Poglavlje 9 kratak pregled

Šta je mrežni menadžment? Okvir Internet-standardnog menadžmenta

Structure of Management Information: SMI Management Information Base: MIB SNMP Protocol Operations and Transport Mappings Bezbednost i administracija

ASN.1

Network Management 9-8/27

SNMP pregled: 4 ključna dela

Management information base (MIB): distribuira informacije skladištenja podataka

mrežnog menadžmenta Structure of Management Information (SMI):

data definition language za MIB objekte SNMP protokol

prenosi manager<->managed object informacije, komande

security, administration sposobnosti glavni dodatak u SNMPv3

Network Management 9-9/27

SMI: data definition languagejezik za definiciju podataka

Purpose: 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 module

Basic Data Types

INTEGERInteger32

Unsigned32OCTET STRING

OBJECT IDENTIFIEDIPaddressCounter32Counter64Guage32

Time TicksOpaque

Network Management 9-10/27

SNMP MIB

OBJECT TYPE:

OBJECT TYPE:OBJECT TYPE:

objects specified via SMIOBJECT-TYPE construct

MIB module specified via SMI MODULE-IDENTITY

(100 standardized MIBs, more vendor-specific)

MODULE

Network Management 9-11/27

SMI: Object, module primeri

OBJECT-TYPE: ipInDelivers MODULE-IDENTITY: ipMIB

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-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}

Network Management 9-12/27

MIB primer: UDP modul

Object ID Name Type Comments

1.3.6.1.2.1.7.1 UDPInDatagrams Counter32 total # datagrams delivered

at this node

1.3.6.1.2.1.7.2 UDPNoPorts Counter32 # underliverable datagrams

no app at portl

1.3.6.1.2.1.7.3 UDInErrors Counter32 # undeliverable datagrams

all other reasons

1.3.6.1.2.1.7.4 UDPOutDatagrams Counter32 # datagrams sent

1.3.6.1.2.1.7.5 udpTable SEQUENCE one entry for each port

in use by app, gives port #

and IP address

Network Management 9-13/27

SNMP Namingquestion: kako dati ime svakom mogućem

standardnom objektu (protokol, podaci, ...) u svakom mogućem mrežnom standardu??

answer: ISO - Object Identifier tree

- stablo identifikacije objekata: hijerarhijski naming svih objekata svaka grana ima ime i broj

1.3.6.1.2.1.7.1ISO

ISO-ident. Org.US DoDInternet

udpInDatagramsUDPMIB2management

Network Management 9-14/27

Check out www.alvestrand.no/harald/objectid/top.html

OSI Stablo identifikacije objekata

Network Management 9-15/27

SNMP protokol

Dva načina da se prenesu MIB informacije, komande:

agent data

Managed device

managingentity

response

agent data

Managed device

managingentity

trap msgrequest

request/response mod trap mod

Network Management 9-16/27

SNMP protokol: tipovi poruka

GetRequestGetNextRequestGetBulkRequest

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 managerof exceptional event

Network Management 9-17/27

SNMP protokol: formati poruka

Network Management 9-18/27

SNMP bezbednost i administracija

encryption: DES-enkripcija SNMP poruke 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 održava bazu podataka prava pristupa, politike za različite korisnike

samoj bazi podataka je moguće pristupiti kao upravljanom objektu!

Network Management 9-19/27

Poglavlje 9 kratak pregled

Šta je mrežni menadžment? Okvir Internet-standardnog menadžmenta

Structure of Management Information: SMI Management Information Base: MIB SNMP Protocol Operations and Transport Mappings Bezbednost i administracija

Problem prezentacije: ASN.1

Network Management 9-20/27

Problem prezentacije

Q: da li savršeno memory-to-memory kopiranje rešava “komunikacioni problem”?

A: ne uvek!

problem: različiti formati poruka, konvencije skladištenja

struct { char code; int x; } test;test.x = 256;test.code=‘a’

a0000000100000011

a

0000001100000001

test.codetest.x

test.code

test.x

host 1 format host 2 format

Network Management 9-21/27

Problem prezentacije iz realnog života

aging 60’s hippie

2004 teenagergrandma

Network Management 9-22/27

Problem prezentacije: potencijalna rečenja

1. 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 Management 9-23/27

Rešavanje problema prezentacije

1. Translate local-host format to host-independent format

2. Transmit data in host-independent format3. Translate host-independent format to remote-host

format

aging 60’s hippie 2004 teenagergrandma

Network Management 9-24/27

ASN.1: Abstract Syntax Notation 1 ISO standard X.680

veoma se koristi na Internet-u like eating vegetables, knowing this “good for you”!

definisani tipovi podataka, konstruktori objekata like SMI

BER: Basic Encoding Rules određuju kako su ASN.1-definisani objekti podataka

koji treba da se prenose svaki objekat koji treba da se prenese ima Type,

Length, Value (TLV) encoding

Network Management 9-25/27

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

1234569

BooleanIntegerBitstringOctet stringNullObject IdentifierReal

Tag Value Type

Network Management 9-26/27

TLV encoding: primer

Value, 5 octets (chars)Length, 5 bytes

Type=4, octet string

Value, 259Length, 2 bytes

Type=2, integer

Network Management 9-27/27

Upravljanje mrežom: zaključak mrežni menadžment

ekstremno važan: 80% mrežnih “troškova” ASN.1 za opis podataka SNMP protokol kao alat za dopremanje

informacija Mrežni menadžment: više umetnost nego nauka

šta da se izmeri/nadgleda kako da se odgovori na greške?