Download Data Communications and NM Overview

Chapter 1
Data Communications
and
NM Overview
Outline
• Analogy of telephone network
•
Data and telecommunication network
•
Distributed computing environment
•
Internet
•
Protocols and standards
•
IT management
•
Network and system management
•
Current status and future of network management
Telephone Network
• Characteristics:
• Reliable - does what is expected of it
• Dependable - always there when you need
it (remember 911?)
• Good quality (connection) - hearing each
other well
• Reasons:
• Good planning, design, and implementation
• Good operation and management of
network
Telephone Network Model
Regional Center
Class 1 switch
Regional Center
Class 1 switch
Sectional Center
Class 2 switch
Sectional Center
Class 2 switch
Primary Center
Class 3 switch
Primary Center
Class 3 switch
Toll Center
Class 4 switch
Toll Center
Class 4 switch
End Office
Class 5 switch
End Office
Class 5 switch
To other
Regional centers
Sectional centers
Primary centers
Toll centers
End offices
To other
Primary centers
Toll centers
End offices
To other
Class 4 toll points
End offices
Legend:
Loop
Direct Trunk
Toll-Connecting Trunk
V oice
V oice
Figure 1.1 Telephone Network Model
Toll Trunk
Operations Systems / NOC
• Monitor telephone network parameters
• S/N ratio, transmission loss, call blockage, etc.
• Real-time management of network
• Trunk (logical entity between switches) maintenance
system measures loss and S/N. Trunks not meeting
QoS are removed before customer notices poor
quality
• Traffic measurement systems measure call blockage.
Additional switch planned to keep the call blockage
below acceptable level
• Operations systems are distributed at central offices
• Network management done centrally from Network
Operations Center (NOC)
Data and Telecommunication Network
Data communication network
Terminal
Terminal
Host
Modem
Modem
Loop
Loop
Modem
Loop
Voice
Voice
Telecommunication network
Figure 1.3 Data and Telecommunication Networks
IBM SNA Architecture
Workstation
Workstation
Cluster
controller
Cluster
controller
Communications
controller
Communications
controller
Mainframe
Figure 1.5 IBM Systems Network Architecture Model
DCE with LAN
DCE.. Distributed Computing Environment
Workstation
Host
Workstation
Ethernet
Workstation
Host
(a) Hosts and Workstations on Local LAN
LAN-WAN Network
LAN A
LAN B
Bridge /
Router
Bridge /
Router
Bridge /
Router
LAN C
WAN
communication link
Client/Server Model
Request
Control
transf er
Client
Server
Control
transf er
Response
Figure 1.7 Simple Client-Server Model
Client/Server Examples
Server
(a) Server with Multiple Clients
Client A
Client
(joe.stone)
Client Z
to [email protected]
Bridge
Mail server
Server
Domain
Name
Server
(b) Dual Role of Client-Server
(a) Server with Multiple Clients
Client
(joe.stone)
Figure 1.8 Client-Server in Distributed Computing Environment
to [email protected]
Bridge
TCP/IP Based Networks
• TCP/IP is a suite of protocols
• Internet is based on TCP/IP
• IP is Internet protocol at the network layer level
• TCP is connection-oriented transport protocol
and ensures end-to-end connection
• UDP is connectionless transport protocol and
provides datagram service
• Internet e-mail and much of the network mgmt.
messages are based on UDP/IP
• ICMP part of TCP/IP suite
Internet
Configuration
Workstation
(Joe)
Mail Server
Workstation
LAN A
Domain
Name
Server
LAN B
Bridge /
Router
Bridge /
Router
Bridge /
Router
LAN C
Gateway
WAN
Gateway
LAN X
Bridge /
Router
Bridge /
Router
Bridge /
Router
LAN Z
LAN Y
Workstation
PC (Sally)
Mail Server
Architecture, Protocols and Standards
• Communication architecture
• Modeling of communication systems, comprising
• functional components and
• operations interfaces between them
• Communication protocols
• Operational procedures
• intra- and inter-modules
• Communication standards
• Agreement between manufacturers on protocols
of communication equipment on
• physical characteristics and
• operational procedures
Communication Architecture
User A
User Z
Peer-Protocol Interface
Application Layers
Application Layers
Transport Layers
Transport Layers
Physical Medium
(a) Direct Communication between End Systems
System A
Intermediate system
System Z
User A
User Z
Peer-Protocol Interface
Application Layers
Application Layers
Transport Layer
Transport Layers
Transport Layers
Conversion
Physical Medium
Physical Medium
(b) Communication between End Systems via an Intermediate System
OSI Reference Model
User / Application program
Layer 7
Application
Layer 6
Presentation
Layer 5
Session
Layer 4
Transport
Layer 3
Network
Layer 2
Data link
Layer 1
Physical
Physical medium
OSI Layers and Services
Layer
No.
Layer Name
Salient services provided by the layer
1
Physical
-Transfers to and gathers from the physical medium raw
bit data
-Handles physical and electrical interfaces to the
transmission medium
2
Data link
-Consists of two sublayers: Logical link control (LLC) and
Media access control (MAC)
-LLC: Formats the data to go on the medium; performs
error control and flow control
-MAC: Controls data transfer to and from LAN; resolves
conflicts with other data on LAN
3
Network
Forms the switching / routing layer of the network
4
Transport
-Multiplexing and de-multiplexing of messages from
applications
-Acts as a transparent layer to applications and thus
isolates them from the transport system layers
-Makes and breaks connections for connection-oriented
communications
-Flow control of data in both directions
5
Session
-Establishes and clears sessions for applications, and
thus minimizes loss of data during large data exchange
6
Presentation
-Provides a set of standard protocols so that the display
would be transparent to syntax of the application
-Data encryption and decryption
7
Application
-Provides application specific protocols for each specific
application and each specific transport protocol system
PDU Communication Model
End System A
User A
End System Z
User Z
UD
Application
(A) PCI
Presentation
(P) PCI
Session
(S) PCI
Transport
(T) PCI
Network
(N) PCI
Data link
(D) PCI
Application
UD
Presentation
(A) PDU
Session
(P) PDU
Transport
(S) PDU
(T) PDU
(N) PDU
Network
Data link
Physical
Physical
(D)PDU Data stream
Physical Medium
PDU: Protocol Data Unit
PDU
=
PCI
+
UD
Figure 1.14 PDU Communication Model between End Systems
PCI: Protocol
Control Information
UDn = PDUn+1
UD: User Data
DTE-A
A
Gateway
N
DTE-N1
Z
N1
N2
A-N-Z Standard Network
N-N1-N2-N3 Subnetwork under Node N
DTE :
Data Terminating Equipment
System A
T
N
D
P
N3
(a) Network configuration
Gateway System N
Transport
Transport
SNICP
SNICP
SNDCP
SNDCP
SNDAP
SNDAP
Subnet system N1
Transport
SNICP
SNDCP-SN
SNDAP-SN
SNDCP-SN
SNDAP-SN
Data link
Data link
Data link-SN
Data link-SN
Physical
Physical
Physical-SN
Physical-SN
Network Medium
Subnetwork Medium
(b) Protocol Communication
SNA, OSI, and Internet
SNA
OSI
End User Application
Application
Presentation Services
Presentation
Data Flow Control
Session
Transmission Control
INTERNET
Transport
SNICP
Path Control
Network
Application Specific
Protocols
Transport
Connection- Connectionless: UDP oriented: TCP
Network
IP
SNDCP
SNDAP
Data Link
Data Link
Not Specified
Physical
Physical
Application Protocols
NM Case Histories
Repeater
Repeater
Repeater
Repeater
Bridge
ISP
Backup ServerMail Server
(a) Multi-Segment Bus LAN with Single Port Bridge Connection
Repeater
Repeater
Repeater
Repeater
Bridge
ISP
Backup ServerMail Server
(b) Dual Multi-Segment Bus LANs with Two-port Bridge Connection
Backup Server Mail Server
Hub
Hub
Hub
Bridge
ISP
(c) Multi-Segment Hub Configuration
Common Network Problems
• Loss of connectivity (Link, Node, Interface)
• Duplicate IP address (Procedural)
• Intermittent problems
• Network configuration issues
• Non-problems
• Performance problems
Challenges of IT Managers
•
•
•
•
•
•
•
•
•
Reliability
Non-real time problems
Rapid technological advance
Managing client/server environment
Scalability
Troubleshooting tools and systems
Trouble prediction
Standardization of operations - NMS helps
Centralized management vs “sneaker-net”
Please refer to Sec. 1.7 for more details
Network Management (NM)

Definition



OAM&P of Network and Services
OAM&P: Operations, Administration,
maintenance, and Provisioning)
Goal

To ensure that the users of a network receive
the IT services with the quality of service
(QoS) that they expect.
Top-down View of NM functions
Network
Management
Network
Provisioning
Network
Operations
Network
Maintenance
Planning
Fault Management / Service Restoration
Fault Management
Design
Configuration Management
Trouble Ticket
Administration
Performance Management / Traffic Management
Network Installation
Security Management
Network Repairs
Accounting Management
Reports Management
Facilities Installation
& Maintenance
Inventory Management
Routine Network
Tests
Data Gathering & Analyses
Figure 1.21 Network Management Functional Groupings
TT
Trouble Ticket
NM Functional Flow Chart
NOC: Network Operation
Center
I&M: Installation &
Maintenance
Network
Users
Configuration Data
Management
Decision
New
Technology
Performance & Traffic Data
Engineering Group
- Network Planning &
Design
TT Restoration
Operations Group
NOC
I & M Group
-Network Installation &
Maintenance
- Network Operations
Fault TT
Installation
網管五大管理功能領域

管理功能領域 (Management Functional
Areas, MFAs)
 障礙管理 (Fault Management)
 組態管理 (Configuration Management)
 安全管理 (Security Management)
 效能管理 (Performance Management)
 計量管理 (Accounting Management)
ITU-T X.700
障礙管理 (Fault Management)



Fault Management (FM)
 Detection of a problem, fault isolation
and correction to normal operation.
FM involves the following steps:
 Discover the problem.
 Isolate the problem
 Fix the problem (if possible)
Use of Trouble-Ticket Systems
障礙管理之功能





Maintain and examine error logs
Accept and act upon error detection
notifications
Trace and identify faults
Carry out sequences of diagnostic tests
Correct faults
障礙管理實例
DNS
UNIX
...
User
PC
FDDI
....
RMON
Device
Firewall
/ Router ....
Internet
....
UNIX
PC
...
Mail
Server
WWW
Server
UNIX
PC
FM例子：障礙存錄
組態管理 (Configuration Management)

Configuration Management (CM)


The process of finding and setting up
(configuring) network devices.
CM identifies, exercises control over,
collects data from, and provides data to
networked systems.
組態管理之功能






Set the parameters that control the routine
operation of the networked system.
Associate names with managed objects and
sets of managed objects.
Initialize and close down managed objects.
Collect information on demand about the
current condition of the networked system.
Obtain announcements of significant changes
in the condition of the networked system.
Change the configuration of the networked
system.
CM 例子: Auto Discovery
CM 實例: 中華電信(CHTNet)
安全管理 (Security Management)

Security Management (SM)


The process of controlling access to
information on the networked system.
安全管理之功能



The creation, deletion, and control of security
services and mechanisms.
The distribution of security-relevant information.
The reporting of security-relevant events.
效能管理 (Performance Management)

Performance Management (PM)


Measuring the performance of network
hardware, software, and media.
幾個量測例子：




Overall throughput
Percentage utilization
Error rate
Response time
效能管理之功能




Gather statistical information.
Maintain and examine logs of system
state histories.
Determine system performance under
natural and artificial conditions.
Alter system modes of operation for the
purpose of conducting PM activities.
PM
例
子
|
網
路
訊
務
量
監
測
計量管理 (Accounting Management)

Accounting Management (AM)


Tracking each individual and group user's
utilization of network resources to better
ensure that users have sufficient resources.
AM enables charges to be established for the
use of network resources, and the costs to
be identified for the use of those network
resources.
計量管理之功能



Inform users of costs incurred or
resources consumed.
Enable accounting limits to be set and
tariff schedules to be associated with the
use of resources.
Enable costs to be combined where
multiple resources are invoked to achieve
a given communication objective.
NM Components
NMS
Network
Agent
Network
Agent
Network
Objects
Network
Objects
Figure 1.24 Network Management Components
Interoperability
NMS
Vendor A
Messages
Services & Protocols
NMS
Vendor B
Network
Agent
Network
Agent
Network
Agent
Network
Agent
Network
Objects
Network
Objects
Network
Objects
Network
Objects
Interoperability (cont.)
Application
Services
Objects
Objects
Vendor A
Management
Protocol
Objects
Vendor B
Objects
Transport
Protocols
(b)Services
Services and
Protocols
& Protocols
Figure 1.23 Network Management Dumbbell Architecture
Network Management Model
Management
Station
MA
Management Operation
Response
Event
Network
Element
MO
Manager
Agent
Communication
Protocols
Communication
Protocols
Network
Legend：
MA: Manager Applications
MO: Managed Objects
R: Real Resource
R
網路管理構成元素




管理者 (Manager)
代理者 (Agent)
網路管理通信協定 (Network Management
Protocol)
網路管理資訊 (Network Management
Information)
網路管理角色

管理者 (Manager)


執行各項用來監督(Monitor)及控制(Control)網
路設備的網管應用程式
代理者 (Agent)

位於網路設備端，負責接受從管理者端送來之
要求，執行所付予之工作，並將結果回報給管
理者。
網路管理協定



網路管理協定專為管理者與代理者所設計之通信協
定。
網路管理協定提供管理者與代理者間交換網管資訊
標準方式。
目前主要兩種網管通信協定

Internet網管通信協定：


SNMP (Simple Network Management)
OSI網管通信協定：

CMIS/P (Common Management Information Service / Protocol)
網路管理資訊

被管物件(Managed Object, MO)



將待管之網路資源，抽象化為物件，稱被管物
件，簡寫MO。
被管物件所代表之網路資源可大可小，大可至
代表整個網路設備如ATM交換器，小可至代表
某一網路元件之參數，如介面卡之狀態。
管理資訊庫 (Management Information
Base)

被管物件之集合，簡寫MIB。
Status and Future Trends
• Status:
• SNMP management
• Limited CMIP management
• Operations systems
• Polled systems
• Future trends:
• Object-oriented approach
• Service and policy management
• Business management
• Web-based management
管理金字塔
(Management Pyramid)
Business Management
Customer Management
Service Management
Distributed System Management
Network Management
Element Management
Functional Areas
Network Types
Configuration
Stages
Performance
IN
VPN
Accounting
Corporate Network
Change
Fault
WAN
Operation
MAN
Accounting
LAN
Installation
Planning
管理範圍 ?
Network Management
System Management
Data
Voice
Applications Management
Service Management
Eneterprise Management
Disciplines
Video
Multimedia
Information Types
網路管理基本方式
network
NM
PC
UNIX
...
網管系統
FDDI
....
Polling
Firewall
/ Router ....
Internet
Notification
RMON
Device
....
UNIX
PC
...
UNIX
PC
網路管理基本方式 (續)

Polling (輪詢)



網管系統主動至被管設備要求網管相關資訊 。
一般採用週期性輪詢，週期長短視需要而定，一
般設為5~15分鐘。
Notification (通報)

網路設備自行發現問題時，主動向網管系統發出
事件報告(Event Report)。