Network Management

Network Management 2110472 Computer Networks Natawut Nupairoj, Ph.D. Department of Computer Engineering Chulalongkorn University

Outline • Introduction to Network Management. • Overview. • Sample Applications. • Simple Network Management Protocol. • History of SNMP. • Basic SNMP Concepts. • MIB Standards. • SNMPv3. • ASN.1.

Overview • Typical System Administrator’s Life • Manage many hosts and network devices. • Detect and response to the PROBLEMS. • Administrators should know the problems BEFORE the users. • Must promise for some Service Level Agreement (SLA) levels • System availability. • Response time. • Throughput.

Overview • What is the scope of network management ? • Monitor for problems • Hosts and services. • Levels of status: up, minor, major, critical. • To reach SLA. • Monitor for tune-up • Should we add more network bandwidth ? For how much ? • Detect the intrusion • Intrusion detection against the hackers.

Overview • Why is it so hard ? • SLA is usually difficult to achieve without good planning and tools • Availability (uptime) – Five Nines = 99.999% • Thus, each host can be down only for • 1 Year = 365 * 24 * 60 = 525,600 minutes. • 0.001% (acceptable downtime) of 1 Year = 5.256 minutes. • This includes maintenance period !!! • How about Six Nines ??? • There are MANY…MANY devices.

System Reliability • Cause of downtime (by Gartner Group)

Sample Network Monitoring Applications • There are several network management applications • OS Tools • Ping, tracerout, netstat, etc. • Freewares • Netsaint, MRTG, snort, etc. • Commercial • CA Unicenter, HP Openview, IBM Trivoli, CiscoWorks.

SNMP SNMPv2 SNMPv2 SMP SNMPv3 SGMP SNMP security (parties) (community) l t t t d d d d d d d d l f f f u r r r r r r n e a e a e a f a a a a a a c r r r o s s i d d d d n d d d d d t o o a e n n n n n n p p i t r a a a n a a a o o e t t t t t t e r r p s s s s s s p p m x e e l p m i 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 SNMP • Simple Network Management Protocol.

Basic SNMP Concepts

Operational Modes

SNMP Structure

name uptime address SNMP MANAGER AGENT SNMP Frameworks – MIB • Management Information Base • MIB Objects • Variables that represent the resources of the system. • Can have several types of values.

SNMP Frameworks - MIB • Structure of Management Information (SMI) • Define a standard way to reference the information. • Describe what includes / what not for each device.

SMI - Example • address • Object ID = 1.1 • Value of Instance = 130.89.16.2 • info • Object ID = 1.2 • name • Object ID = 1.2.1 • Value of Instance = printer-1 • uptime • Object ID = 1.2.2 • Value of Instance = 123456 • ALTERNATIVE: • Object ID = NEW-MIB info uptime

Standard SMI

MIB-II – Internet MIB

MIB ExampleHost Resources MIB

SNMP Operations

PDU Structure

SNMPv3 – Security Enhancements

ASN.1 • Abstract Syntax Notation 1 • Similar to BNF notation for programming language. • Define how data should be sent, in what order. • The protocol designer must write ASN.1 to define the protocol • Programming language designer uses BNF to define the grammar of the language. • Encode in binary format.

ASN.1 - Example • How can I send an integer 65534 ? • 2 bytes: 1111 1111 1111 1110 • Big-endian or little-endian ? • Sender uses little-endian, receiver uses big-endian. • 1111 1110 1111 1111 = 65279 • What if I want to send a whole structure ? struct { char code; int x; }

ASN.1 Syntax Definition • Define a data type • Define based on built-in types and other data types defined in the file. • Built-in types: INTEGER, OCTET STRING, REAL, BOOLEAN, etc. • Newly-defined data type can be complicated • SEQUENCE, SEQUENCE OF, CHOICE, etc. • Format • <name> ::= <description -- components>

ASN.1 Examples -- -- The currency codes from ISO 4217 -- are used to identify a currency -- Currency ::= OCTET STRING ObjectId ::= INTEGER DateTime ::= SEQUENCE { timeOffsetCode TimeOffsetCode, localTimeStamp LocalTimeStamp }

ASN.1 Encoding Rules • Syntax definition defines the components of the data. • Encoding defines how to actually store the data. • Data can be encoded in several ways. • Basic Encoding Rule (BER). • Distinguished Encoding Rule (DER). • Packed Encoding Rule (PER).

BER Encoding • Basic Encoding Rule (BER) • Tag Length Value (TLV). TAG LENGTH VALUE MyId ::= [APPLICATION 12] INTEGER 12 4 1234 (this is not the actual encoded data.)

BER Encoding • Constructed Encoded Form T LT L T L V T L V DateTime ::= [APPLICATION 83] SEQUENCE { timeOffsetCode TimeOffsetCode, localTimeStamp LocalTimeStamp } TimeOffsetCode ::= [APPLICATION 232] Code LocalTimeStamp ::= [APPLICATION 16] NumberString Code ::= [APPLICATION 243] INTEGER

References • J. Kurose and K. Ross, Computer Networking: A Top-Down Approach Featuring the Internet, Addison Wesley, 2001. • Netsaint, http://www.netsaint.org. • The SimpleWeb Tutorials, http://www.simpleweb.org/tutorials/. • Electronic and telecommunication Institute, Lessons about SNMP, http://www.et.put.poznan.pl/snmp/main/mainmenu.html. • Yoram Cohen, SNMP – Simple Network Management Protocol, http://www.rad.com/networks/1995/snmp/snmp.htm.

Network Management