Network Management UnitVI Network Management Basic principals Infrastructure

Network Management Unit-VI: Network Management: Basic principals, Infrastructure 4 n/w management, The internet netowrk management framework: SMI, MIB, SNMP details, Security & administration, ASN. 1, Firewalls: Packet filtering and application Gateways r introduction to network management m motivation m major components r Internet network management framework m MIB: management information base m SMI: data definition language m SNMP: protocol for network management m security and administration r presentation services: ASN. 1 Unit 6 1

What is network management? r autonomous systems (aka “network”): 100 s or 1000 s of interacting hardware/software components r other complex systems requiring monitoring, control: m jet airplane m nuclear power plant m others? "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. Unit to 6 meet the 2

Infrastructure for network management definitions: managing entity agent data managing data entity network management protocol managed devices contain managed device managed objects whose data is gathered into a agent data Management Information Base (MIB) managed device agent data managed device Unit 6 3

Network Management standards OSI CMIP r Common Management Information Protocol r designed 1980’s: the unifying net management standard r too slowly standardized SNMP: Simple Network Management Protocol r Internet roots (SGMP) r started simple r deployed, adopted rapidly r growth: size, complexity r currently: SNMP V 3 r de facto network management standard Unit 6 4

SNMP overview: 4 key parts r Management information base (MIB): m distributed information store of network management data r Structure of Management Information (SMI): m data definition language for MIB objects r SNMP protocol m convey manager<->managed object info, commands r security, administration capabilities m major addition in SNMPv 3 Unit 6 5

SMI: data definition language Purpose: syntax, semantics of management data welldefined, unambiguous r base data types: m straightforward, boring r OBJECT-TYPE m data type, status, semantics of managed object r MODULE-IDENTITY m groups related objects into MIB module Basic Data Types INTEGER Integer 32 Unsigned 32 OCTET STRING OBJECT IDENTIFIED IPaddress Counter 32 Counter 64 Guage 32 Time Ticks Opaque Unit 6 6

SNMP MIB module specified via SMI MODULE-IDENTITY (100 standardized MIBs, more vendor-specific) MODULE OBJECT TYPE: objects specified via SMI OBJECT-TYPE construct Unit 6 7

SMI: Object, module examples OBJECT-TYPE: ip. In. Delivers OBJECT TYPE SYNTAX Counter 32 MAX-ACCESS read-only STATUS current DESCRIPTION “The total number of input datagrams successfully delivered to IP userprotocols (including ICMP)” : : = { ip 9} MODULE-IDENTITY: ip. MIB MODULE-IDENTITY LAST-UPDATED “ 941101000 Z” ORGANZATION “IETF SNPv 2 Working Group” CONTACT-INFO “ Keith Mc. Cloghrie ……” DESCRIPTION “The MIB module for managing IP and ICMP implementations, but excluding their management of IP routes. ” REVISION “ 019331000 Z” ……… : : = {mib-2 48} Unit 6 8

MIB example: UDP module Object ID Name Type Comments 1. 3. 6. 1. 2. 1. 7. 1 UDPIn. Datagrams Counter 32 total # datagrams delivered at this node 1. 3. 6. 1. 2. 1. 7. 2 UDPNo. Ports Counter 32 # underliverable datagrams no app at portl 1. 3. 6. 1. 2. 1. 7. 3 UDIn. Errors Counter 32 # undeliverable datagrams all other reasons 1. 3. 6. 1. 2. 1. 7. 4 UDPOut. Datagrams Counter 32 # datagrams sent 1. 3. 6. 1. 2. 1. 7. 5 udp. Table SEQUENCE one entry for each port in use by app, gives port # and IP address Unit 6 9

SNMP Naming question: how to name every possible standard object (protocol, data, more. . ) in every possible network standard? ? answer: ISO Object Identifier tree: m hierarchical naming of all objects m each branchpoint has name, number 1. 3. 6. 1. 2. 1. 7. 1 ISO-ident. Org. US Do. D Internet udp. In. Datagrams UDP MIB 2 management Unit 6 10

OSI Object Identifier Tree Check out www. alvestrand. no/harald/objectid/top. html Unit 6 11

SNMP protocol Two ways to convey MIB info, commands: managing entity request response agent data Managed device request/response mode managing entity trap msg agent data Managed device trap mode Unit 6 12

SNMP protocol: message types Message type Get. Request Get. Next. Request Get. Bulk. Request Inform. Request Set. Request Response Trap 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 Unit 6 13

SNMP protocol: message formats Unit 6 14

SNMP security and administration r encryption: DES-encrypt SNMP message r authentication: compute, send MIC(m, k): compute hash (MIC) over message (m), secret shared key (k) r protection against playback: use nonce r view-based access control m SNMP entity maintains database of access rights, policies for various users m database itself accessible as managed object! Unit 6 15

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 = 256; test. code=‘a’ test. code test. x a 000000011 host 1 format test. code test. x a 00000011 00000001 host 2 format problem: different data format, storage conventions Unit 6 16

A real-life presentation problem: grandma 2004 teenager aging 60’s hippie Unit 6 17

Presentation problem: potential solutions 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? Unit 6 18

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 grandma aging 60’s hippie 2004 teenager Unit 6 19

ASN. 1: Abstract Syntax Notation 1 r ISO standard X. 680 m used extensively in Internet m like eating vegetables, knowing this “good for you”! r defined data types, object constructors m like SMI r BER: Basic Encoding Rules m specify how ASN. 1 -defined data objects to be transmitted m each transmitted object has Type, Length, Value (TLV) encoding Unit 6 20

TLV Encoding Idea: transmitted data is self-identifying m T: data type, one of ASN. 1 -defined types m L: length of data in bytes m 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 Unit 6 21

TLV encoding: example Value, 259 Length, 2 bytes Type=2, integer Value, 5 octets (chars) Length, 5 bytes Type=4, octet string Unit 6 22

Network Management: summary r network management m extremely important: 80% of network “cost” m ASN. 1 for data description m SNMP protocol as a tool for conveying information r Network management: more art than science m what to measure/monitor m how to respond to failures? m alarm correlation/filtering? Unit 6 23