차세대 인터넷 망관리 기술
2000. 12. 12
이재용
연세대학교 전기전자공학과
jyl@nasla.yonsei.ac.kr
차세대 인터넷
~2002
TCP/IP 기반의
유선 Web 응용 서비스
~2005
QoS 제공 기반의
Web 응용 서비스
(Intserv/Diffserv)
개 인: ADSL (1.544Mbps)
사무실: 고속 LAN (10Mbps)
유·무선 고속 통합 인터넷
무선 인터넷
무선 모뎀 (64Kbps)
IMT-2000 (128K ~ 2Mbps)
All-IP 무선 인터넷
개 인: 6Mbps
사무실: 10Mbps
Traditional SNMP Management
 Basic Functions
 Admin framework
DB
Server
For Long-term
Analysis
NMS
Functions
handling
 MIB browser
 Applications
 Fault mgmt
 Configuration mgmt
 Accounting mgmt
 Performance mgmt
 Security mgmt
Periodic polling
Using SNMP
Agent
Agent
Agent
Device
Device
Device
 Other functions
 DB interface
차세대 인터넷 망 관리 요구사항
통합 망으로 인한
관리 망 크기의 증대
확장성
(Scalability)
새로운 서비스 출현으로
인한 서비스 관리
유연성
(Flexibility)
End-to-End QoS
보장 관리
강인성
(Robustness)
고속화에 따른
관리
End-to-end
Scope
분산 관리
Paradigm의
필요성
- 구조
•관리 통신
•Agent
•Master
- 관리 객체
분산 망 관리 동향 (1)
 구조적 측면
 OSF (Open Software Foundation)
 DME(Distributed Management Environment)
 IETF (Internet Engineering Task Force)
 AgentX (Agent Extensibility Protocol)
 ITU/TMN
 ODMA (Open Distributed Management Architecture)
 FIPA (Foundation for Intelligent Physical Agents)/OMG
 Mobile Agent
분산 망 관리 동향 (2)
 관리 객체 측면
 OMG
 CORBA (Common Object Request Broker Architecture)
 SUN etc.
 Java RMI(Remote Method Invocation)
 JMX(Java Management eXtension)
 IETF
 RMON I, RMON II
 Functional MIB (Expression MIB, Event MIB, Scheduling MIB)
 ITU
 Event Notification / M-Action
WBEM Architecture
Other
Windows
Management App
Management App
DCOM / XML
DCOM / XML
Managed
Node
Common
Information
Model (CIM)
CIM Object Manager
COM
Object Providers
XML
Managed
Objects
CMIP
CMIP
Objects
SNMP
SNMP
Objects
RPC
DMI
Objects
Win32
Win 32
Objects
BMC software 구조
CORBA-based Inter-domain Manager
Using Web
HTML
JAVA Applet
JAVA Applet
CORBA (Orbix Web)
HTML(CGI)
WEB
Browser
RMI
CORBA – based
Inter-domain Manager
ORB
CORBA/SNMP gateway
CORBA/SNMP gateway
SNMP Sub-domain
Agent
Agent
Agent
CORBA Sub-domain
Agent
Agent
Agent
CMIP Sub-domain
Agent
Agent
Agent
망관리에서의 분산화 :
Event Notification/M-Action
 NM client의 load를 줄여줌
 Event filtering / Correlation
NMS
Notification
이 요구됨
M-Action
 Event 발생은 미리 작성된
Scenario에 의함
 Event 발생에 대한 reaction
Server
Server
Server
Action
은 NMS에 의존하므로 신속한
대응 미흡
망관리에서의 분산화 : RMON
Host a
Host b
Host c
Interface 2
Subnet X
RMON
Probe
NMS
Subnet Y
Interface 1
Host d
Host e
- Network-layer address에 근거한
통계자료 모음 (nlHOST)
• Control table
Subnet Spec
Subnet Spec
X
Y
RMON 1
- Subnetwork-wide 통계 제공
- Off-line 관리 (data gathering)
- alarm defing and event reporting
- frame filtering and capturing
RMON 2
- End-to-End 통계자료 제공
• email, file transfer.www에 따른 응용계층
트래픽을 감시
• host들에서 특정 application의 트래픽을
기록 가능
단점 RMON 장비의 CPU, memory 낭비
• Data Table
Host related statistics
Host related statistics
Host related statistics
••
•
# of input packets / octets
# of output packets / octets
망관리에서의 분산화 : Mobile Agent
Distributed Management : Management by Delegation (MbD)
 지적능력을 스스로 갖고 새로운 프로세스를 만
들어 낼 수 있다 (Autonomy)
NMS
Script
(code, data, state)
 Server간에 이동이 가능하다 (Mobility)
(remote execution 또는 migration)
Results
Server
Server
분산된 일을 server를 지나며 수행 가능
(Intelligence)
비동기적으로 망 관리 수행 가능
(Asynchronousity)
망 관리에서 확장성과 유연성을 중대시한다
 표준화그룹 : FIPA, OMG MASIF
Server
 Platform : Aglet,Concordia,grasshopper,
Voyager
* FIPA : Foundation for Intelligent Physical
Agent
* OMG : Object Management Group
* MASIF : MOBILE Agent System Interoperability Facility
Distributed Objects
 Common Object Request Broker Architecture
 Web-Based Enterprise Management
 Java Management eXtensions
CORBA (1)
 Object Management Architecture
 standardized by OMG
 Joint Inter-Domain Management (JIDM) group
 Sponsored by Open Group and the TMF
(Telecommunication Management Forum)
 Provide tools that enable management system based on
CMIP, SNMP, and CORBA to work together.
 Provide CMIP/CORBA and SNMP/CORBA inter-working.
 Map between GDMO/ASN.1 and CORBA IDL.
 Map between SNMP SMI and CORBA IDL.
CORBA (2)
Manager
Client
(Caller)
Object
(Callee)
Stub
Skeleton
Middleware(ex. ORB)
SNMP CMIP
IDL
CORBA
Objects
Network
ASN.1
Objects
Object Request Broker (ORB)
SNMP domain
 Web 기술과의 통합을 시도
 Orbix Web from IONA
 CorbaWeb from academia
GDMO
Objects
CMIP domain
CORBA domain
WBEM
 Desktop Management Interface(DMI)에서 제기됨
 Web-Based Enterprise Management (WBEM)
 초기에는 HMMS, HMMP, and HMOM로 구성됨
 Drastic upheaval of WBEM
 Common Information Model (CIM)
 CIMOM이 HMOM을 대치.
 HTTP 과 XML 을 수용함.
 Current work
 Integrating CIM with CORBA and Java-based management.
 Developing SNMP/CIM, DMI/CMI, and CMIP/CIM gateway.
Java technologies
 Java RMI
 Can be combined with Object Serialization.
 Management objects (SNMP or CMIS/CMIP objects) are
mapped into distributed Java objects.
 JMAPI (Java Management API)
 Based on Java RMI
 Set of tools and guidelines to build management applets.
 Supports the most common SNMP MIB (MIB-II)
 JMX (Java Management eXtension)
 A management framework destined for object-oriented
web-based management.
 SNMP API, WBEM API, (already specified) and TMN API
(currently under definition)
 SNMP-to Java MIB compiler (translates the managed
objects into MBean Component)
JMX
 JMX Architecture
 Instrumentation level : give instant manageability to any
object
 Agent level : provide management agent.
 Manager level : provide management component operating
as manager or agent.
 JMX Components
 JMX Manageable Resource
 JMX Agent
 JMX Manager
 Services for management
 Addition Management Protocol APIs
 Interacting with other management environments.
Key Component of JMX
Proprietary Management
Application
Web Browser
Proprietary Management
Application
Manager
Level
JMX Manager
Protocol
Adaptors
Agent
Level
MBean
Server
Service
Object 2
Instrumentation
Level
Object 1
Object 3
Java virtual machine
MBean (registered in the server)
Java virtual machine
Plain JavaBeans Component (not registered)
AgentX (Agent Extensibility Protocol)
Motivation for AgentX
 Distributed management의 필요성
 Hierarchical framework.
 Management applications의 분산된 agent에 대한 투명한 접근
 Managed objects의 동적인 확장
 MIB 장비로부터 SNMP protocol engine을 분리
 MIB 구현 모듈의 동적인 추가
AgentX Framework
Manager
SNMP
SNMP
Entity
AgentX
Dispatcher
AgentX Master-Agent
Extensibility
protocol
SubAgent
SubAgent
SubAgent
 Master agent
 Agent 역할로서 SNMP 프
로토콜 메시지의 송수신.
 MIB에는 거의 직접적으로
접근하지 않음.
 Subagent(s)
 Master-agent에 의해 처
리되는 SNMP 메시지로부
터 “Shielded”됨.
 MIB을 직접 접근.
AgentX Roles – Master Agent
 기능
 Subagent로부터 AgentX session 확립 요구를 받아들임.
 Subagent로부터 MIB region의 등록 접수
 현재 등록된 MIB region에 따라, AgentX 프로토콜이 MIB에 접근
 Subagent를 위해 notification을 전달해줌.
AgentX Roles - Subagent
 기능
 Master-agent와 함께 AgentX session 시작
 Master-agent에게 MIB region을 등록
 등록된 MIB region내에서 OID와 실제 variable을 bind 시킴
 Variable에 대한 관리 동작을 수행
 관리 객체 (MO: Managed Object)를 초기화 시킴
 Notification을 주도
Example: Management with AgentX
Subagent
From a manager’s point of view, an
extensible agent behaves exactly as
would a monolithic agent.
Mail Server
Email MIB
AgentX
NMS
SNMP
Subagent
Master Agent
AgentX
MIB Registry
WWW MIB
AgentX
The master agent is MIB ignorant
and SNMP omniscient while the
subagent is SNMP ignorant and MIB
omniscient.
WWW Server
Subagent
10baseT Hub
Repeater MIB
AgentX Protocol Operations
 18 Protocol operations are defined.
 7 PDUs for Master agent  Subagent direction
 10 PDUs for Subagent  Master agent direction
 1 PDU for both Master agent and subagent.
 Master agent  Subagent
 Get-PDU, GetNext-PDU, Get-Bulk-PDU, TestSet-PDU, CommitSetPDU, UndoSet-PDU, and CleanupSet-PDU.
 Subagent  Master agent
 Open-PDU, Close-PDU, Register-PDU, Unregister-PDU, Notify-PDU,
Ping-PDU, IndexAllocation-PDU, IndexDeallocation-PDU,
AddAgentCaps-PDU, and RemoveAgentCaps-PDU.
 Both side
 Response-PDU
OID Registration
 Subagents may register single instances:
 E.g., 1.3.6.1.2.1.25.1.2.0 = HOST-RESOURCESMIB.hrSystemDate.0
 Subagents may register OID regions:
 E.g., 1.3.6.1.2.1.2.2.1.[1-22].7 = IF-MIB.ifIndex.7 – IFMIB.ifSpecific.7
 Only a single subagent can be “authoritative” for a
particular OID region.
 Priority values are used to identify the authoritative
subagent if regions overlap.
Transport Layer Mappings
 AgentX defines the following transport mappings:
 AgentX over TCP
 The master agent accepts TCP connection requests for the
well-known port 705.
 Subagents connect to the master agent using 705 port
number.
 AgentX over UNIX-domain Sockets
 The master agent creates a well-known UNIX-domain socket
endpoint called “/var/agentx/master”.
 AgentX PDUs are not encoded using the BER
 They are transmitted as a contiguous byte stream. (Unlike
SNMP PDUs)
Security Considerations
Community
NMS
USEC for v3
Master
Agent
No mechanism
Subagent
 Agent session 동안 SNMP 보안 관련 정보가 subagent에게 전달되
는 방법이 없다.
Implementations and Products
 JAX – A Java AgentX Sub-Agent Toolkit





 http://www.ibr.cs.tu-bs.de/projects/jasmin/jax.html
CMU AgentX Implementation
 http://www.net.cmu.edu/groups/netdev/agentx/
Compaq True64 UNIX version5.0
 mailto: daniele@zk3.dec.com
Epilogue Envoy
 http://www.isi.com
UC Davis, SNMP suites
 ucd-snmp.ucdavis.edu
Frank Fock, Agent++
 http://www.fock.de/agent++
AgentX Limitations
 Requires relatively complex operations on the master
agent side in order to realize SNMP lexicographical
ordering and access control efficiently.
 Only a single subagent can be “authoritative” for a
particular OID regions.
 Only one network device which has same MIB can be
managed at the same time.
 Security mechanism is not considered.
Functional MIBs
Expression MIB
Event MIB
Scheduling MIB
Remote Operations MIBs
Notification Log MIB
Expression MIB
expValueEntry
expObjectEntry
A table of object
definitions for each
Used by
expExpressionEntry
row
(OID, wildcard…)
A table of values
from evaluated
expressions
Produce
expExpressionEntry Result
Information about
a single expression
(Interval, Prefix…)
Produce
Error
expErrorEntry
Information about
errors in processing
an expression
 목적: 망관리 시스템에서 네트워크 트래픽 overhead를 줄이기
위함
 MIB variable에 대한 expression computation 수행
 Expression 구성시 3가지 MIB object sampling 형태 지원

absolute, delta, changed (boolean sampling).
Event MIB
 목적
 MIB variable이 threshold를 지나치거나, 변화된 값을 가질 때
event를 발생시키기 위함
 다른 MIB과의 관계
 [RFC1757] RMON alarm, event group의 능력에 대한
superset 제공
 [RFC1905] SNMPv2의 Manager-Manager MIB의 계승/보완
 [RFC2573] SNMPv3 Management Target과 Notification MIB
의 서비스에 의존
 [RFC2982] 분산 관리 Expression MIB을 보완한다.
Scheduling MIB
schedEntry
schedOwner SnmpAdminString,
schedName SnmpAdminString,
schedDescr SnmpAdminString,
schedInterval Unsigned32,
schedWeekDay BITS,
schedMonth BITS,
schedDay BITS,
schedHour BITS,
schedMinute BITS,
schedContextName SnmpAdminString,
schedVariable VariablePointer,
schedValue Integer32,
schedType INTEGER,
schedAdminStatus INTEGER,
schedOperStatus INTEGER,
schedFailures Counter32,
schedLastFailure SnmpPduErrorStatus,
schedLastFailed DateAndTime,
schedStorageType StorageType,
schedRowStatus RowStatus
 목적
 주기적 또는 주어진 날짜와 시
간에 수행될 action에 대한
scheduling
 동작
 Control object를 변경시켜
schedule을 enable/disable
시킴
 다른 관리 기능에 의해 활성화/
비활성화 되는 schedule을 미
리 구성할 수 있게 함.
Remote Operations MIBs
 Ping MIB
 Remote host에서 관리 응용으로 하여금 Ping 수행 가능케 함.
 Traceroute MIB
 Remote host에서 Traceroute 수행케 함.
 Lookup MIB
 Remote host에서 Name lookup 가능케 함.
Notification Log MIB
 목적
 Local loggin 기능의 형태로 다른 MIB에게 common
infrastructure 제공
 주로 sender의 Notification을 위해 사용되나 receiver도 사용 가
능.
nlmLogEntry
nlmStatsLogEntry
nlmConfigLogEntry
A table of Notification
A table of logging
log statistics entries statistics
control entries.
(logged or bumped)
(entry limit, filter…)
contains
A table of Notification
log entries
(variables…)
has
nlmLogVariableEntry
A table of variables
to go with Notification
log entries
(values…)
Script MIB
Overview of the Script MIB(1)
 Defined in RFC2592
 SNMP-compliant MIB
 Script MIB
 분산된 장소로 Script 전달
 Script를 위한 argument 전달
 동작중인 script의 monitor, control이 원격으로 가능
 Running script로 부터 결과 받음.
Overview of the Script MIB(2)
• Consists of six tables
mib - II
scriptMIB(mib-2 64)
smObjects
smLangTable
smExtsnTable
smScriptObject
smScriptTable
smCodeTable
smRunObjects
smLaunchTable
smRunTable
–
–
–
–
–
–
Language
Extension
Script
Code
Launch
Run
• OID is (mib-2 64)
Table (1)
 Language Table
 Agent가 지원하는 언어 정보 제공.
 E.g. Java, and Tcl etc.
 Extension Table
 Language 확장에 대한 정보 제공
 Local resource나 network protocol에 대한 interface제공 가능.
Table (2)
 Script Table
 Script MIB을 지원하는 network 장비에 설치된 모든 script를 나
열
 Script를 설치/제거, script 상태를 변경/읽기 등을 가능케하는
object 가짐.
 지정된 URL로 부터 script를 Agent에 의해 영원히 설치되고, 받아
질 수 있음.
 Code Table
 SNMP set operation에 의해 Agent에게 script를 도착하게(push)
함.
Table (3)
 Launch Table
 준비된 script를 서술
 List의 각 entry는
 Script에서 전달된 argument
 Script 수행중의 신뢰도, 허가등을 나타냄.
 Run Table
 최근 끝나거나, 돌고 있는 script list
 Manager로 하여금 동작되고 있는 script에 대한 정보 추출이나 제
어 가능케 함.
Operations of Script MIB
Manager
Script Repository
HTTP or other
push script
pull script
smLangTable
Java
JDK1.1.8
Perl
5.004
③
①
smScriptTable
Preinstalled
Preinstalled
Dynamic
-loaded
Dynamic
-loaded
SNMP agent
②
⑤
④
smLaunchTable
smRunTable
ⓢ
Info
Access
ⓢ
args secutiry
Launch
ⓢ
args
state
result
ⓢ
Info
Access
ⓢ
args secutiry
Launch
ⓢ
args
state
result
ⓢ
Info
Access
ⓢ
args secutiry
Launch
ⓢ
args
state
result
ⓢ
Info
Access
ⓢ
args secutiry
Launch
ⓢ
args
state
result
Network
Node
Applications of Script MIB
 Scripts as Agent
 Scripts as Mid-level manager
 Monitoring
 Service testing (QoS monitoring)
 Service management and control
 Fault handling
Scripts as Agent
 Agent를 확장하거나 구현
 표준 MIB로 부터 관리정보를 computing하는 서비
manager
스 제공
 Agent의 확장성 제공.
Launch script
Retrieving result
Internet Server
Script
Repository
Polling
Script MIB
agent
MIB-II
(ex. tcpConnTable)
response
Scripts for monitoring
 Monitoring
 Detecting irregular
condition
 Collecting accounting data
 More scalable
 The number of node to be
monitored
 MIB objects per node
 Significantly decrease
M : Manager
A : Agent
manager
mid-level M
manager A
M
A
management traffic.
 Pre-process monitored data
A
A
 More flexible
 Easy to add nodes to be
monitored
 Easy to modify the set of
MIB objects monitored.
A
A
Script for service testing
 Service testing (QoS
monitoring)
manager
 Checking the availability and
the static and dynamic
parameters of a given services.
Internet
Server
Launch
script
 Introducing new MIB module
 Lacks flexibility for new
services
Send
test packet
result
 Service testing by Script MIB
Receive
services
MIB
Agent
User
Rapidly adaptable to new
situation.
 Script MIB agent is located
where potential users are
(differ from central manager).
 Script MIB can be installed on
several remote location which
require service monitoring.
Script for service deployment and
control
 Local mid-level managers
 can control server
processes
 are running on the same
node as the processes.
Web
server
manager
Download script
Check
service
 The Script MIB offers a
convenient solution for
the rapid development
and installation of
network services.
 example)
 Remote service
deployment on
programmable switch.
Programmable
switch
Control network
Scripts for fault handling

Web server
(repository)
②Choose
manager
Adequate script

③Install script

①Fault
notification
④Execution
⑤Remove script
Fault handlings can be
distributed to mid-level
manager as script.
Central manager only
required to decide which
fault handling procedure to
apply.
Procedures
①
②
③
④
⑤
Fault identification
Choose adequate script
Install script
Start and execute script
Remove script
References (1)
 Sun, “Java Management Extension White Paper,”


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http://java.sun.com/products/JavaManagement
WBEM Initiative, Online: http://www.dmtf.org/wbem
CORBA, Online: http://www.omg.org/
M. Daniele et al., “Agent Extensibility (AgentX) Protocol
Version 1,” , RFC2741, January 2000.
L. Heintz et al., “Definitions of Managed Objects for
Extensible SNMP Agents,” , RFC2742, January 2000.
R. Kavasseri and Bob Stewart, “Event MIB,” , RFC2981,
October 2000
R. Kavasseri and Bob Stewart, “Distributed Management
Epression MIB,” , RFC2982, October 2000.
References (2)
 Bob Stewart and Ramanathan R. Kavasseri, “Notification
Log MIB,” , internet draft, draft-ietf-disman-notif-logmib-16.txt, February 2000.
 Kenneth White, “Definitions of Managed Objects for
Remote Ping, Traceroute, and Lookup Operations,” ,
RFC2925, September 2000.
 D. Levi and J. Schönwälder, “Definitions of Managed
Objects for Scheduling Management Operations,” ,
RFC2591, May 1999.
 D. Levi and J. Schönwälder, “Definitions of Managed
Objects for the Delegation of Management Scripts,” ,
RFC2592, May 1999
References (3)
 J Schönwälder, “Emerging Internet Management Technologies,”
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IM’99 Tutorial, 1999.
Jürgen Schönwälder, Jürgen Quittek and Cornelia Kappler,
“Building Distrubuted Management Applications with the IETF
Script MIB,” IEEE Journal on Selected Areas in
Communications, vol. 18, no. 5, May 2000.
David Levi, “Introduction to the Script MIB,” Simple Times, vol.
7 no. 2, Nov. 1999.
Éamonn McManus, “Script MIB Implementation Experience,”
Simple Times, vol. 7 no. 2, Nov. 1999.
Frank Strauß, “Script MIB Performance Analysis,” Simple
Times, vol. 7 no. 2, Nov. 1999.
Jürgen Quittek and Cornelia Kappler, “Practical Experiences
with Script MIB Application,” Simple Times, vol. 7 no. 2, Nov.
1999.