NMT ASSIGNMENT 1
Q1)
a) Explain two-tier network management organization model.
Ans- The organization model describes the components of network management and
their relationships below shows a representation of a two-tier model
Network objects consists of network elements such as hosts, hubs,
bridges, routers etc They can be classified into managed and unmanaged
objects of elements.
The managed elements have a management process winning in them, the
manager communicates with the agent in the managed elements. The
managed elements have a management process running in them called an
agent which is absent in unmanaged elements.
The manager managed the managed element, there is a database in the
manager but not in agent the manager queried & received management
data from agent processors them and stored in database. The agent can
also send a minimal set of alarm information to the manager unsolicited.
b) Compare between CMIS/CMIP and SNMP.
Ans-
CMIS/CMIP SNMP
It takes more memory and It takes less memory and
processing’s resources from a processing’s resources from a
device. device.
It is based on vector It is based on scalar
technology. technology.
It is a part of OSI protocol. It is part of TCP/IP protocol.
It provides with better reporting It doesn’t provide with good
of unusual network conditions. reporting of unusual network
conditions.
It is a safer system with built-in It is not as safe a system as
security for authorization, CMIS/CMIP.
access control etc.
c) Explain TNM conceptual model.
Ans- i. From a TMN point of view, the network management system (NMS) is
treated as an operations system, as shown in Figure2. It manages the data
communication and telecommunications network.
ii. It is logically a separate network, but it may or may not be physically separate,
based on the implementation selected.
iii. The telecommunications network shown consists of switching exchange and
transmission system network elements. It is primarily the WAN of
communications.
iv. The switching systems contain both analog and digital switches. Hence the
transmission systems are both analog and digital and include all transport facility
modes, including twisted pair, coaxial, fibre optics, and wireless.
d) Explain the challenges faced by network managers while managing a
network.
Ans- Top challenging activities in managing the network:
• Rapid advance of technology
• Problem analysis—needs human intuition and skill besides
sophisticated management tools
• Anticipate customer demands
• Acquire and retain human resources
• Manage client–server environment in converged networks
• Networking with emerging technology necessitates the need for
continuing education
• Collaborative research between academic institutions and industry
• Maintain reliability, that is, make changes, upgrades, etc. without
disrupting the network and impacting business
• Diagnose problems or outages in a non-disruptive manner (without
impacting other users on the network)
• Estimate the value of a technology transition
Q2)
a) Explain the purpose of TRAP and discuss SNMP TRAP’s.
Ans- SNMP traps are used in the management of a data network. SNMP traps
enable an agent to notify the management station of significant events by way of an
unsolicited SNMP message. In this diagram, the setup on the left shows a network
management system that polls information and gets a response. The setup on the
right shows an agent that sends an unsolicited or asynchronous trap to the network
management system (NMS).
The idea behind trap-directed notification is that if a manager is responsible for a
large number of devices, and each device has a large number of objects, it is
impractical for the manager to poll or request information from every object on every
device. The solution is for each agent on the managed device to notify the manager
without solicitation. It does this by sending a message known as a trap of the event.
After the manager receives the event, the manager displays it and can choose to
take an action based on the event. For instance, the manager can poll the agent
directly, or poll other associated device agents to get a better understanding of the
event. Trap-directed notification can result in substantial savings of network and
agent resources by eliminating the need for frivolous SNMP requests. SNMP
requests are required for discovery and topology changes. In addition, a managed
device agent cannot send a trap, if the device has had a catastrophic outage.
SNMPv1 traps are defined in RFC 1157, with these fields:
1. Enterprise—Identifies the type of managed object that generates the trap.
2. Agent address—Provides the address of the managed object that generates
the trap.
3. Generic trap type—Indicates one of a number of generic trap types.
4. Specific trap code—Indicates one of a number of specific trap codes.
5. Time stamp—Provides the amount of time that has elapsed between the last
network reinitialization and generation of the trap.
6. Variable bindings—The data field of the trap that contains PDU. Each variable
binding associates a particular MIB object instance with its current value.
b) Describe various SNMP commands with syntax.
Ans- SNMP commands:
DISABLE SNMP- Enter this command to disable SNMP and all
SNMP related commands. Be default, SNMP is disabled. Syntax-
disable snmp.
ENABLE SNMP- Enter this command to enable SNMP and all SNMP
related commands. By default, SNMP is disabled. Syntax- enable
snmp.
SET SNMP TRAPCOMMUNITY- Enter this command to set the trap
community string. By default, the value is “COMPAQ”. Syntax- set
snmp trapcommunity {<"Trap community string">}
SET SNMP TRAPDEST- Enter this command to set up to three
SNMP trap destinations. Trap destinations cannot be FQDN
addresses, you must use IPv4 addresses only. Specify none to
remove a trap destination. Syntax- set snmp trapdest {,1 / 2 / 3 }
{[none] / []}
SHOW SNMP- Enter this command to show all SNMP configuration
settings. Syntax- show snmp.
TEST SNMP- Enter this command to send a test trap to all of the
configured trap destinations. The command sends a standard test
trap (11003) for the test. See SNMP trap codes and descriptions for a
list of the SNMP trap codes and descriptions. Syntax- test snmp
Q3)
a) Explain ATM network management.
Ans- The Network Management Working Group of the ATM Forum has developed an
end-to-end generic management model that encompasses private and public
networks and lays out standards for interworking between them. The model defines
gateways between SNMP and CMIP systems, and between standards-based and
proprietary systems. Five key management interfaces are defined in this model,
labelled M1-M5.
M1 is concerned with the management of the end-user equipment connecting to
either private or public switches. M2 undertakes management of private ATM
switches and networks. Private ATM network management is addressed through MI
combined with M2. M4 deals with their public ATM switches and networks. M3 is the
link between private and public networks, used for exchanging fault, performance
and configuration information. Finally, M5 supports interactions between any two
public networks. The definition of these interfaces allows a complete management
service, ranging from a global view of the network (M5 management inter-face) to the
management of individual elements (M1 management interface). In some cases,
several management interfaces use the same information from a management
information base (MIB) tree.
M1/M2 Interfaces and the ILMI Implementation:
i) The Interim Local Management Interface (ILMI), which is an implementation of the
MI /M2 interfaces. ILMI enables the exchange of status, configuration, accounting
and control information between any two ATM devices - such as two ATM switches -
across a user-to-network inter-face (UNI).
ii) For ILMI to function, every ATM switch or network terminator and every ATM
network that deploys a public or private network UNI must be equipped with a UNI
Management Entity (UME) which supports an ILMI MIB. Two adjacent (or peer)
UMEs can communicate using the common attributes provided by the ILMI.
iii) By sending SNMP commands, a UME may obtain or modify information contained
in its ILMI MIB. The ILMI MIB is hierarchically organised (Table2). It contains
information concerning each group listed in Table. Also defined are functions that
allow retrieval and handling of information in the ILMI MIB.
iv) The ILMI has been deployed by some vendors to perform management tasks
across the UNI for some devices. However, since the ILMI provides a solution that is
applicable only at the UNI, it cannot support the management tasks that are involved
in a network comprising a range of ATM devices. Thus, on its own, the ILMI does not
provide the capability to manage multi-vendor ATM networks.
b) Explain security user model (USM) of SNMP v3.
Ans- RFC 2274 defines the user-based security model (USM) for SNMPv3. This
specification encompasses:
Authentication: Provides data integrity and data origin authentication. The
message authentication code HMAC, with either the hash function MD5 or
SHA1 provides authentication.
Timeliness: Protects against message delay or replay.
Privacy: Protects against disclosure of message payload. The cipher block
chaining (CBC) mode of DES is used for encryption.
Message format: Defines format of msgSecurityParameters field, which sup-
ports the functions of authentication, timeliness, and privacy.
Discovery: Defines procedures by which one SNMP engine obtains
information about another SNMP engine.
Key management: Defines procedures for key generation, update, and use.
USM Security Parameters: UsmSecurityParameters that specifies the internal format
of the msgSecurityParameters field in SNMPv3 message.
Authoritative SNMP Engine: In any message transmission, one of the two entities,
transmitter or receiver; is designated as the authoritative SNMP engine, according to
the following rules.
When an SNMP message contains a payload which expects a response, then
the receiver of such messages is authoritative.
When an SNMP message contains a payload, which does not expect a
response (for example an SNMPv2-Trap, Response, or Report PDU), then the
sender of such a message is authoritative.
Thus, for messages sent on behalf of a Command Generator and for Inform
messages from a Notification Originator, the receiver is authoritative.
The field msgSecurityParameters in SNMPv3 messages has a data type of octet
string. This designation serves two purposes. The first one is,
The timeliness of a message is determined with respect to a clock maintained
by the authoritative engine.
When an authoritative engine sends a message (Trap, Response, Report), it
contains the current value of its clock, so that the non-authoritative recipient
can synchronize on that clock.
When a non-authoritative engine sends a message (Get, GetNext, GetBulk,
Set, Inform), it includes its current estimate of the time value at the
destination, allowing the destination to assess the message's timeliness.
The second one is,
A key localization process, described later, enables a single principal to own
keys stored in multiple engines; these keys are localized to the authoritative
engine in such a way that the principal is responsible for a single key but
avoids the security risk of storing multiple copies of the same key in a
distributed network.
It makes sense to designate the receiver of Command Generator and Inform
PDUs as the authoritative engine, and therefore the possessor of the
authoritative clock in an exchange.
If a response or trap is delayed or replayed, little harm should occur. However,
Command Generator and, to some extent, Inform PDUs result in management
operations, such as reading or setting MIB objects.
Thus, it is important to guarantee that such PDUs are not delayed or replayed,
which could cause undesired effects
1) Elements of UsmSecurityParameters :
When an outgoing message is passed to the USM by the Message Processor,
the USM fills in the msgSecurityParameters field. When an incoming message
is passed to the USM by the Message Processor, the USM processes the
values contained in msgSecurityParameters.
The security parameters field consists of the following elements:
o MsgAuthoritativeEngineID: The snmpEnginelD of the authoritative
SNMP engine involved in the exchange of this message. Thus, this
value refers to the source for a Trap, Response, or Report, and to the
destination for a Get, GetNext, GetBulk, Set, or Inform.
o MsgAuthoritativeEngineBoots: The snmpEngineBoots value of the
authoritative SNMP engine involved in the exchange of this message.
The object snmpEngineBoots is an integer in the range 0 through
(2)^31-1 that represents the number of times that this SNMP engine
has initialized or reinitialized itself since its initial configuration.
o MsgAuthoritativeEngineTime: The snmpEngineTime value of the
authoritative SNMP engine involved in the exchange of this message.
The object snmpEngineTime is
an integer in the range 0 through (2)^31- 1 that represents the number of
seconds since this authoritative SNMP engine last incremented the
snmpEngineBoots object. Each authoritative SNMP engine is responsible for
incrementing its own snmpEngineTime value once per second. A non
authoritative engine is responsible for incrementing its notion of
snmpEngineTime for each remote authoritative engine with which it
communicates.
MsgUserName: The user (principal) on whose behalf the message is being
exchanged.
MsgAuthenticationParameters: Null if authentication is not being used for this
exchange. Otherwise, this is an authentication parameter. For the current
definition of USM, the authentication parameter is an HMAC message
authentication code.
MsgPrivacyParameters: Null if privacy is not being used for this exchange.
Otherwise, this is a privacy parameter. For the current definition of USM, the
privacy parameter is a value used to form the value (IV) in the DES CBC
algorithm.
Q4)
a) Explain various M interfaces used between ATM end user or device and
ATM network.
Ans- There are 5 interfaces between system and network.
fig: ATM forum mgmt. interface reference architecture
Private n/s s are managed by private n/w managers are private n/w systems
(NMS)
public n/w manages
M1 and M2 are interfaces between private NMS and either end user or private
N/W.
The end user can lie a work station ATM switch or any ATM device
A private ATM n/w is an enterprise n/w
A private NMS can access its own n/s related info in a public n/w via M3
interface to public NMS
M4 is the interface between NMS of turn service providers
The user interface to the private n/w is private user n/w interface (UNI) and the
interface to the public n/w is public UNI.
b) Explain ATM remote monitoring.
Ans- M1 Interface: Management of ATM Network Element: The M1 interface is
between an SNMP management system and an SNMP agent in an ATM device.
Four entities, ifInNUcastPkts, ifOutNUcastPkts, ifOutQLen, and ifspecific have been
deprecated. The interfaces (interfaces) and ifMIB (IF MIB) groups under the mgmt.
node.
M2 Interfaces and the ILMI Implementation: Interim Local Management Interface
(ILMI), which is an implementation of the M I /M2 interfaces, enables the exchange of
status, configuration, accounting and control information between any two ATM
devices - such as two ATM switches - across a user-to-network interface (UNI). For
ILMI to function, every ATM switch or network terminator and every ATM network
that deploys a public or private network UNI must be equipped with a UNI
Management Entity (UME) which supports an ILMI MIB. Two adjacent (or peer)
UMEs can communicate using the common attributes provided by the ILMI. By
sending SNMP commands, a UME may obtain or modify (if the object is indeed
modifiable) information contained in its ILMI MIB. The ILMI has been deployed by
some vendors to perform management tasks across the UNI for some devices.
However, since the ILMI provides a solution that is applicable only at the UNI, it
cannot support the management tasks that are involved in a network comprising a
range of ATM devices.
M3 Interface: Customer Network Management of Public Networks: The M3
management interface is between the private NMS and the public NMS. It allows
customers to monitor and configure their portions of the public ATM network. Class I
requirements are those that a public NMS offers to the customer, monitoring and
management of configuration, fault, and performance of a specific customer's portion
of a public ATM network. This service is offered only for a permanent virtual circuit
(PVC) configuration. Examples of this service are (1) retrieving performance and
configuration information for a UNI link and (2) public NMS reporting of a UNI link
failure via an alarm or trap message to the user NMS. Class II service provides
greater capability to the user, who can request the public NMS to add, delete, or
change virtual connections between pairs of the customers’ UNIs. An example would
be a customer wanting to establish a new virtual path or increase the number of
virtual circuits in a given virtual path. A customer network management (CNM)
manages both private and public ATM networks. A CNM agent residing in the public
ATM network provides the M3 service. The service is limited to the portion of the
public service provider's network that the user's circuit traverses. If the user's circuit
traverses multiple service providers, a separate interface with each provider is
needed. The CNM sends requests to the carrier management system (see Figure1),
which acts as an agent to the CNM. The carrier management system then invokes
the request on the network elements or other NMS and returns the responses to
CNM.
M4 Interface: Public Network Management: The management of public ATM network
is primarily the responsibility of network service providers, carriers and Postal
Telephone and Telegraph (PTT) companies. They have the challenge of not only
managing the public network, but also keeping up with new technology.
M5 Interface: The final interface M5 is between the NMSs of two service providers. It
is most complicated of all interfaces. M5 supports interactions and exchange of
management information between any two public networks. M5 supports interactions
and exchange of management information between any two public networks.
Q5)
a) Describe network management information model.
Ans- Information model:
Network management information model is concerned with the
structure and storage of information.
It is the representation of objects and information that are relevant
to their management forms. It forms the management information
model.
The information base is called the management information base.
The information model specifies the information base to describe
managed objects and relationships between many objects.
The structure defining syntax and semantics of management
information is specified by SMI (structure of management
information).
The manager has both MDB and MIB.
MDB is the real database whereas MIB is the virtual database.
b) Describe network management communication and function model.
Ans- The third model in OSI management is the communication model, which
has three components: management application processes that function in
the application layer, layer management between layers, and layer
operation within the layers. Communication Model deals with the way that
information is exchanged between the agent and the manager and between
the managers. There are three key elements in the communication model:
transport protocol, application protocol and the actual message to be
communicated.
The functional model is the fourth component of OSI management, and it
deals with the user-oriented requirements of network management. OSI
defines five functional application areas, namely, configuration, fault,
performance, security, and accounting. These are defined as system
management functions in OSI. Functional Model comprises five functional
areas of network management, which are discussed in more detail in the
next section.
Q6)
a) Explain the need for TNM and hence OSI network management
architecture.
Ans-
b) Explain the services offered by CMISE.
Ans- The Common Management Information Service (CMIS) is the service
interface specified in ITU. It defines the service interface that is
implemented by the Common Management Information Protocol (CMIP)
as specified in ITU-T Recommendation.
The OSI CMISE management services are presented in figure1.
OSI CMISE management services
Management operation services:
M-CREATE – Create an instance of a managed object
M-DELETE – Delete an instance of a managed object
M-GET – Request managed object attributes (for one object or a set of
objects)
M-CANCEL-GET – Cancel an outstanding GET request
M-SET – Set managed object attributes
M-ACTION – Request an action to be performed on a managed object
Management notification services:
M-EVENT-REPORT
Management association services:
M-INITIALIZE
M-TERMINATE
M-ABORT
