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

Basic SNMP Concepts

Operational Modes

SNMP Structure

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

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 info name uptime ALTERNATIVE: 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 Example Host 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 Format 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).

(this is not the actual encoded data.) 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 L T 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.