1. Chapter 9: Network Management
Chapter goals:
introduction to network management
motivation
major components
Internet network management framework
MIB: management information base
SMI: data definition language
SNMP: protocol for network management
security and administration
presentation services: ASN.1
Network Management

2. Chapter 9 outline What is network management?
Internet-standard management framework
Structure of Management Information: SMI
Management Information Base: MIB
SNMP Protocol Operations and Transport Mappings
Security and Administration
ASN.1
Network Management

3. What is network management?
autonomous systems (“network”): 100s or 1000s of interacting hardware/software components
other complex systems requiring monitoring, control:
jet airplane
nuclear power plant
others?
"Network management includes the deployment, integration and coordination of the hardware, software, and human elements to monitor, analyze, evaluate, and control the network.
Network Management

4. What is network management?
Lets see One analogy first
Imagine that ur the head of a large organization that has several branch offices around the world
Its your job to make sure that the pieces of your organization are operating smoothly
How will you do so?
You will periodically gather data from your branch offices in the form of reports & budget
Network Management
9-4

5. Then pass order (make this change) to the branch office.
You will occasionally (but not always) be explicitly notified when there is a problem in one of the branch offices
The branch manager may send you unsolicited (unwanted) reports indicating how smoothly things are running at his or her branch
You will see the reports try to find out the solution on that problem that need your attention
You might initiate a one-on-one dialogue with one of your problem branch offices, gather more data in order to understand the problem
Then pass order (make this change) to the branch office.
Network Management
9-5

6. There are three major components of a network management architecture:
This is very common human scenario for controlling the organization – the boss (you), the remote sites being controlled (the branch offices), your remote agents (the branch office managers), communication protocols (for transmitting reports and data)
The architecture of a network management system is conceptually identical to our analogy
There are three major components of a network management architecture:
A managing entity (the boss), the managed devices (the branch office) and the network management protocol with agent data (branch manager)
Network Management
9-6

7. A managed device is a piece of network equipment (including its software) that resides on a managed network (branch office)
A managed device might be a host, router, hub, modem, within managed device there may be several managed objects
These managed objects are the actual pieces of hardware within managed device (ex: network interface card)
Network Management
9-7

8. In our human analogy the managed objects might be the departments within the branch office
In each managed device is a network management agent (a process running in the managed device that communicate with managing entity
The last piece of network management architecture is the network management protocol (protocol runs between managing entity & managed device)
Network Management

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

10. Internet-standard management Framework
SNMP: Simple Network Management Protocol
(SNMP) It is used for network management in the internet for moving management data between a management entity & its agents
started simple
deployed, adopted rapidly
growth: size, complexity
currently: SNMP V3
Network Management

11. Chapter 9 outline What is network management?
Internet-standard management framework
Structure of Management Information: SMI
Management Information Base: MIB
SNMP Protocol Operations and Transport Mappings
Security and Administration
ASN.1
Network Management

12. SNMP overview: 4 key parts
Management information base (MIB):
distributed information store of network management data( the MIB defines information conveyed between the branch office & main office)
Structure of Management Information (SMI):
data definition language for MIB objects (that defines data types, rules for writing & revising management information)
SNMP protocol (conveying information & commands between a managing entity & agent)
convey manager<->managed object info, commands
security, administration capabilities
major addition in SNMPv3(major enhancement)
Network Management

13. Structure of Management Information SMI
SMI: The Structure of Management Information is language used to define the management information residing in a managed network entity
Such a definition language is needed to ensure that the syntax and semantics of the network management data are well defined & unambiguous (clear-cut, unmistakable)
Basic Data Types
INTEGER
Integer32
Unsigned32
OCTET STRING
IPaddress(32 bit ip add.)
Counter32
Counter64
Time Ticks (Time Measured)
Network Management
9-13

14. In addition to the basic data types, the SMI data definition language also provides higher level language constructs
The OBJECT-TYPE construct is used to specify the data type, status and semantics of a managed object
Collectively these managed objects contain the management data that lie at the heart of network management
The OBJECT-TYPE constructs has four clauses
The SYNTAX clause of an OBJETC-TYPE definition specifies the basic data type associated with the object

15. The MAX-ACCESS clause specifies whether the managed object can be read, be written
The STATUS clause indicates whether the object definition is current and valid
The DESCRIPTION clause contains a human-readable textual definition of the object
ipInDelivers OBJECT TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
“The total number of input
datagrams successfully
delivered to IP user-
protocols
Counter32: keeps track of the number of IP datagrams that were received at managed device

16. The MODULE- IDENTITY construct allows related objects to be grouped together within a “module”
In addition to containing the OBJECT-TYPE definition of the managed objects within the module
The MODULE-IDENTITY constructs contains clauses to document contact information of the author of module
The date of the last update, a revision history and textual description of the module.
Ex: consider module definition for management of the IP protocol

17. Editors of this version:
MODULE-IDENTITY: ipMIB
ipMIB MODULE-IDENTITY
LAST-UPDATED “ Z”
ORGANZATION “IETF SNMPV2
Working Group”
CONTACT-INFO
“ Keith McCloghrie
Postal:Cisco Systems, 170 West
Tasman
Drive, CA , US
Phone:
……”
DESCRIPTION
“The MIB module for managing IP
and ICMP implementations”
IETF:
The Internet Engineering Task Force (IETF) develops and promotes Internet standards
Editors of this version:
The MODULE-IDENTITY statement is where information is collected such as the module's purpose, the organization responsible for the module, and contact information for the module's authors
Network Management

18. MODULE IDENTITY moduleIdentityName MODULE-IDENTITY
LAST-UPDATED "timestamp"
ORGANIZATION "text"
CONTACT-INFO "text"
DESCRIPTION “text"
The MODULE-IDENTITY statement is where information is collected such as the module's purpose, the organization responsible for the module, and contact information for the module's authors.
It also contains revision tracking information -- in the form of a timestamp (A timestamp is a sequence of characters, denoting the date and/or time at which a certain event occurred)for the last update
Network Management

19. Network Management

20. Network Management

21. Network Management

22. Network Management

23. Network Management

24. Network Management

25. SNMP Protocol Operations
The Simple Network Management Protocol is used to convey MIB information among managing entities and agents
The most common usage of SNMP is in a request response mode in which managing entity sends a request to agent
Who receives the request, performs some action, and sends a reply to the request
Network Management

26. A second common usage of SNMP is for an agent to send an unsolicited (unwanted) message, known as a trap message, to a managing entity
Trap messages are used to notify a managing entity of an exceptional situation
The network administrator might want receive a trap message for ex: when an interface goes down(system & hardware related problem), congestion in a network, or an authentication failure event, the loss of a neighbor, a link going up or down
Network Management

27. request/response mode
SNMP protocol
Two ways to convey MIB info, commands:
managing
entity
managing
entity
request
trap msg
response
agent
data
agent
data
Managed device
Managed device
request/response mode
trap mode
Network Management

28. SNMP protocol: message types
SNMP defines seven types of messages known generically as protocol data units-PDUs
The GetRequest, GetNextRequest and GetBulkRequest PDUs are all sent from a managing entity to an agent to request at the agents managed device
The SetRequest PDU is used by a managing entity to set the value (make changes) of one or more MIB objects in a managed device
An agent replies with a Response PDU with the “noError” message
Network Management

29. The InformRequest PDU is used by a managing entity to notify another managing entity of MIB information that is remote to receiving entity
The final type is the trap message (managing entity requires notification) congestion in a network, or an authentication failure event, the loss of a neighbor, a link going up or down
Network Management

30. SNMP protocol: message types
Function
GetRequest
GetNextRequest
GetBulkRequest
Mgr-to-agent: “get me data”
(instance, next in list, block)
Mgr-to-mgr: inform remote managing
Entity of MIB values
InformRequest
SetRequest
Mgr-to-agent: set MIB value (mke chng
Agent-to-mgr: value, response to
Request
Response
Trap
Agent-to-mgr: inform manager
of exceptional event
Network Management

31. Chapter 9 outline What is network management?
Internet-standard management framework
Structure of Management Information: SMI
Management Information Base: MIB
SNMP Protocol Operations and Transport Mappings
Security and Administration
The presentation problem: ASN.1
Network Management

32. 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 = 259;
test.code=‘a’
test.code
test.x a
test.code
test.x a
host 1 format
host 2 format
problem: different data format, storage conventions
Network Management

33. ASN.1 (Abstract Syntax Notation) is an ISO-originated standard that is used in a number of Internet-related protocols, particularly in the area of network management
The different computer architectures, different operating system and different compilers have different conventions for storing and representing data
So the different computers store and represent data in different ways though your data is same.(means exact copy from one host to another)
Network Management

34. Memory Address Big-Endian Byte Value Little-Endian Byte Value
Example
Four-Byte Integer: 0x
Memory Address Big-Endian Byte Value Little-Endian Byte Value
Little-Endian:
If the hardware is built so that the lowest, least significant byte of a multi-byte scalar is stored "first", at the lowest memory address, then the hardware is said to be "little-endian
Big-Endian:
If the hardware is built so that the highest, most significant byte of a multi-byte scalar is stored "first", at the lowest memory address, then the hardware is said to be "big-endian"
Network Management

35. Real World Presentation Problem:
Neither receiver understands the essential idea being communicated –that the speaker likes something
The Phrase whose meaning is great, special, incredible(usually indicating stylishness in 1920)
Network Management

36. A real-life presentation problem:
grandma
2004 teenager
aging 60’s
hippie
Network Management

37. Presentation problem: potential solutions
Sender learns receiver’s format and translates into receiver’s format. Sender sends.
Sender sends. Receiver learns sender’s format and translate into receiver-local format
Sender translates host-independent format and sends. Receiver translates to receiver-local format.
Third option is to have a machine-independent , OS-independent, language-independent
A presentation service can solve this problem by translating the idea into a commonly understood(by presentation service), person-independent language, sending that information to receiver, then translating into a language understood by the receiver

38. 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
aging 60’s
hippie
grandma
2004 teenager
Network Management

39. ASN.1: Abstract Syntax Notation 1
ISO standard
used extensively in Internet
defined data types, object constructors
like SMI
BER: Basic Encoding Rules
specify how ASN.1-defined data objects to be transmitted
each transmitted object has Type, Length, Value (TLV) encoding
(here value 259 decimal which equals , in binary or byte value of 1 followed by byte value of 3)
Network Management

40. 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
Tag (Type)Value Type 1 2 3 4 5
Boolean
Integer
Bitstring
Octet string
Null
Network Management

41. TLV encoding: example Value, 259 Length, 2 bytes Type=2, integer
Value, 5 octets (chars)
Length, 5 bytes
Type=4, octet string
Network Management

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