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

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

3. 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.

4. 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.

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

7. System Reliability
Cause of downtime (by Gartner Group)

8. 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.

13. SNMP Simple Network Management Protocol. SGMP SNMP SMP SNMPv2d 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

14. Basic SNMP Concepts

15. Operational Modes

16. SNMP Structure

17. 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

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

19. SMI - Example address info name uptime ALTERNATIVE: Object ID = 1.1
Value of Instance =
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 =
ALTERNATIVE:
Object ID = NEW-MIB info uptime

20. Standard SMI

21. MIB-II – Internet MIB

22. MIB Example Host Resources MIB

23. SNMP Operations

24. PDU Structure

25. SNMPv3 – Security Enhancements

26. 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.

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

28. 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>

29. 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 }

30. 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).

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

32. 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

33. References
J. Kurose and K. Ross, Computer Networking: A Top-Down Approach Featuring the Internet, Addison Wesley, 2001.
Netsaint,
The SimpleWeb Tutorials,
Electronic and telecommunication Institute, Lessons about SNMP,
Yoram Cohen, SNMP – Simple Network Management Protocol,