1. Chapter 8 Network Management
Communication Networks
P. Demeester
Chapter 8 Network Management
Computer networking - A top-down approach featuring the internet 4th Edition, 2008 Addison Wesley James F. Kurose, Keith W. Ross ISBN
Network Management

2. Chapter 8: 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
Network Management

3. Chapter 8 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
Network Management

4. What is network management?
autonomous systems (“network”): 100s or 1000s of interacting hardware/software components
"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 to meet the real-time, operational Performance, and Quality of Service requirements at a reasonable cost."
Network Management

5. FCAPS : fault, configuration, accounting, performance, security
Fault Management : log, detect, respond to fault conditions in the network
(similar to performance management, but short term; e.g.
link failure, power shut down, …)
Configuration Management : track which devices are in the network,
what the hardware and software configurations are, … (e.g. router,
hubs, switches, …)
Accounting Management : specify, log and control user and device access
to the network (e.g. usage quotas, usage based charging, …)
Performance Management : quantify, measure, report, analyze, and control
the performance of different network components (router, host,
link but also end-to-end abstractions) (long term, in contrast to
fault management, e.g. average packet loss rate, …)
Security Management : control access to resources (e.g. KDC and CA)
Network Management

6. Infrastructure for network management
definitions:
managed devices contain
managed objects whose
data is gathered into a
Management Information
Base (MIB)
managing device
agent
data
managing
entity
Central
MIB
managed device
network
management
protocol
agent
data
Examples :
- monitoring traffic
- detecting NIC failures
- monitoring hosts are up
- …
managed device
Network Management

7. Network Management standards
OSI CMIP
Common Management Information Protocol
designed 1980’s: the unifying net management standard
too slowly standardized
SNMP: Simple Network Management Protocol
Internet roots (SGMP)
started simple
deployed, adopted rapidly
growth: size, complexity
currently: SNMP V3
de facto network management standard
Network Management

8. Chapter 8 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
Network Management

9. SNMP overview: 4 key parts
Structure of Management Information (SMI):
data definition language for managed objects
Management information base (MIB):
distributed information store of network management data
SNMP protocol
convey manager<->managed object info, commands
security, administration capabilities
major addition in SNMPv3
Typically the whole framework is called SNMP (not only the protocol part)
Network Management

10. SMI: data definition language
Purpose: - syntax, semantics of management data
- well-defined, unambiguous
base data types:
straightforward
OBJECT-TYPE
base data type, status, semantics of managed object
MODULE-IDENTITY
groups related objects into a MIB module
Network Management

11. Basic Data Types INTEGER Integer32 Unsigned32 OCTET STRING
OBJECT IDENTIFIER
IPaddress
Counter32
Counter64
Guage32
TimeTicks
Opaque
Examples :
OCTET STRING : byte-string representing
arbitrary binary or textual data,
up to bytes long
OBJECT IDENTIFIER : assigned name to
object element (sequence of up
to 128 integers)
TimeTicks : time, measured in 1/100ths
of a second since some event
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12. OBJECT-TYPE Specify the data-type, status and semantics
of a managed object (nearly defined objects)
OBJECT-TYPE construct has 4 clauses :
- SYNTAX : basic data type associated with object
- MAX-ACCESS : what is allowed : read, write, create,
include value in notification
- STATUS : current and valid, obsolete, deprecated
- DESCRIPTION : human-readable definition of 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 (including ICMP)”
::= { ip 9}
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13. MODULE-IDENTITY
Allows related objects to be grouped together within a module
(MIB module)
ipMIB MODULE-IDENTITY
LAST-UPDATED “ Z”
ORGANZATION “IETF SNMPv2 Working Group”
CONTACT-INFO
“ Keith McCloghrie
……”
DESCRIPTION
“The MIB module for managing IP and ICMP implementations, but excluding their management of IP routes.”
REVISION “ Z”
::= {mib-2 48}
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e.g. RFC 2011 (MIB for the internet protocol using SMIv2)

14. Chapter 8 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
Network Management

15. MIB : Management Information Base
- MIB : virtual information store, holding managed objects whose values
collectively reflect the current status of the network
- managed objects specified by OBJECT-TYPE SMI
- managed objects grouped in MIB modules (using MODULE-IDENTITY)
- over 100 standards-based MIB modules (even larger number vendor
specific (private) MIB modules)
MODULE
OBJECT TYPE:
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16. Object Naming
How to name every possible standard object (protocol, data, more..) in every possible network standard ?
ISO Object Identifier tree:
hierarchical naming of all objects
each branchpoint has name, number
ISO
ISO-ident. Org.
US DoD
Internet
udpInDatagrams
UDP
MIB2
management
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17. ASN.1 Object Identifier Tree
ISO(1)
ISO identified
Organization (3) US
DoD (6)
Internet (1)
management (2)
MIB-2 (1)
UDP(7) x
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18. MIB example: UDP module
Object ID Name Type Comments
UDPInDatagrams Counter32 total # datagrams delivered
at this node
UDPNoPorts Counter32 # undeliverable datagrams
no app at port
UDPInErrors Counter32 # undeliverable datagrams
all other reasons
UDPOutDatagrams Counter32 # datagrams sent
udpTable SEQUENCE one entry for each port
in use by app, gives port #
and IP address
Network Management

19. Chapter 8 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
Network Management

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

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

22. SNMP protocol summary SNMP manager UDP IP DL PHY Management
application
SNMP agent
UDP IP DL
PHY
Management agent
application
managed
objects
SNMP managed objects
GetRequest
GetResponse
GetRequest
GetResponse
GetNextRequest
Trap
GetNextRequest
Trap
SetRequest
SetRequest
SNMP
messages
Public Internet
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23. SNMP Example subtree : ipRouteTable 1.3.6.1.2.1.4.21 ipRouteEntry
ipRouteDest
ipRouteMetric1
ipRouteNextHop 3 5
ipRouteTable
subtree :
ipRouteEntry =X
ipRouteDest
X.1
ipRouteMetric1
X.3
ipRouteNextHop
X.7
ipRouteDest X
ipRouteDest X
ipRouteDest X
ipRouteMetric X
ipRouteMetric X
ipRouteMetric X
ipRouteNextHop X
ipRouteNextHop X
ipRouteNextHop X
See : “Advanced Network Administration” S. Wisniewski, Prentice Hall, 2003
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24. SNMP Example
GetRequest (ipRouteDest , ipRouteMetric ,
ipRouteNextHop )
GetResponse ((ipRouteDest = , ipRouteMetric = 3,
ipRouteNextHop = )
GetNextRequest (ipRouteDest, ipRouteMetric1, ipRouteNextHop)
GetResponse ((ipRouteDest = , ipRouteMetric = 3,
ipRouteNextHop = )
GetNextRequest (ipRouteDest , ipRouteMetric ,
ipRouteNextHop )
GetResponse ((ipRouteDest = , ipRouteMetric = 3,
ipRouteNextHop = )
GetNextRequest (ipRouteDest , ipRouteMetric ,
ipRouteNextHop )
GetResponse ((ipRouteDest = , ipRouteMetric = 5,
ipRouteNextHop = )
ipRouteDest
ipRouteMetric1
ipRouteNextHop 3 5
Network Management

25. SNMP : message formats : PDU
PDU-type
Request-id
Variable bindings
GetRequest, GetNextRequest, SetRequest
PDU-type
Request-id
Error-status
Error-index
Variable bindings
GetResponse
name1
value1
name2
value2
name3 …
Request-id : each request has a unique identification number
Error-status : (0) noError, (1) tooBig, (2) noSuchName, (3)badvalue, …
Error-index : additional information by indicating which variable caused
the exception
Variable bindings : list of names and corresponding values
(value Null in case of request)
Network Management

26. Chapter 8 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
Network Management

27. SNMP security and administration
application
Command
generator
Notification
receiver
Proxy
forwarder
Command
responder
originator
Others
PDU
Dispatching
Message
Processing
system
Timeliness
Authentication
Privacy
Access
control
SNMP
engine
Security/message header
PDU
Transport layer
Network Management

28. SNMP security and administration
encryption: DES-encrypt SNMP PDU (symmetric key !)
authentication/integrity: HMAC (Hashed Message Authentication Codes)
Authentication (using K, key known by sender and receiver)
Protection against tampering (using H(.))
protection against playback: use nonce
view-based access control
SNMP entity maintains database of access rights, policies for various users
database itself accessible as managed object! K + m
H(.)
H(m,K)
Internet + m
Network Management

29. Network Management: summary
extremely important: 80% of network “cost”
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

30. Table of contents What is network management ? 3
Internet-standard management framework
Structure of Management Information: SMI 8
Management Information Base: MIB 14
SNMP Protocol Operations and Transport Mappings 19
Security and Administration 26
Table of contents
Network Management