TTM4128: Network and Service Management
With regards to the basic foundation of network mangement, there are three models: Organization Model, Information Model and Communciation model.
Organization model components:
- Manager in Management system
- Agent in Managed system
- Sends requests to agents.
- Monitors alarms from agents.
- Houses applications.
- Provides user services.
- Gathers information from managed object instances.
- Configures paramters of managed object instances.
- Responds to mangagers' requests.
- Generates alarms and sends them to manager.
- Structure of Management Information (SMI)
- Syntax and semantics for the defintion of the managed object types.
- Management Information base (MIB)
- The library system of the managed object types.
- Management Information tree (MIB tree)
- A hierarchical identification system for the managed object types.
Manager (which contains applications) sends requests to the Agent (which contains Network elements/Managed Objects). The Agent sends responds and notifications/traps to the Manager.
FCAPS, coined by ISO, presents some of the major challenges faced by the network manager:
- Fault management
- Detection and isolation of failures in network; Trouble ticket administration; Manageing the occurence of fualty events such as disconnetions at virtual connections, links, and interfaces.
- Configuration management
- Set and change network configuration and compontnet parameters; Set up alarm thresholds; tuning various network devices.
- Accounting management
- Charging and billing the use of resources in an enterprise.
- Performance management
- Measurements of performance metrics and actions.
- Security management
- Prevent unauthorized access, attacks, and protecting data.
Role of the Information model in the SNMP information model framework
The role of the Information Model framework is to define managed object types as well as an identification system for managed object types. Content is SMI and MIB. The role of SMI is to define a language basis for defintion and identifcation of Management Object Types. The language applied is ASN.1 Management Object Types are defined by the OBJECT-TYPE MACRO. MIB defines the collection of Managed Object Types. Management Object Types are identified by the posistion in the MIB tree.
5 different PDU. 3 From manager and 2 from agent.
- Manager requests value of a managed object from agent.
- Manager requests value of the next managed object ot the one specified.
- Manager initializes or changes the value of managed object.
- Agent responds with value for get and set requests from the manager.
- Alarm generated by an agent.
Web services can search for other web services through the invocation of a service provided by a service broker.
- The binding describes the message protocol with which the service can be reached. The protocol is HTTP
Operations between actors
- Publish: A service provider can tell the service broker about the services it provides by using the publish interface on the service broker.
- Find: The service requestor communicates with the Service broker to find a particular web service.
- Bind: Describes the message protocol with which the service can be reached, e.g. SOAP over HTTP. There can be multiple different bindings for the same portType in a WSDL document.
- Invoke: Represents the actual invocation of a Web Service and can be compared to a function call, where parameters are passed to the function and return values is received as result.
Random (but important) facts about NETCONF.
- NETCONF is an IETF network mangement protocol
- It is used for configuration (while SNMP turned out to be primarily used for monitoring)
- It evolved from the fact that operators widely used command line to configure equipment.
- It provides mechanisms to install, change, and remove the configuration of network devices.
- It uses SSH as transport protocol, and defines its operations on top of an RPC layer (rpc and rpc-reply)
- It uses the Yang language to define manged object types in its framework.
NETCONF has 4 layers:
- Content (Layer 4)
- The configuration data, typically XML.
- Operations (Layer 3)
- The command describing the task we want to execute. get, edit, copy, delete.
- Messages (Layer 2)
- The implementation of RPC (remote procedure calls) following the netconf standard.
- Secure transport (Layer 1)
- Transport protocol layer. Beep, SSH, HTTPS.
There are 4 NETCONF operations.
- get-config(source, filter)
- Retrieve a (filtered subset of a) configuration from the configurationdatastore source.
- edit-config(target, default-operation, test-option, error-option, config)
- Edit the target configuration datastore by merging, replacing, creating, or deleting new config elements.
- copy-config(target, source)
- Copy the content of the configuration datastore source to the configuration datastore soruce to the configuraiton datastore target.
- Delete hte named configuration datastore target.
Assuming a NETCONF tool will be used instead of SNMP or CIM. SSH would be a good transport protocol to use for the NETOCONF based management tool
When changing some of the parameters on one of the equipment using NETCONF, the basic steps that should be done to configure an equipment are:
- Lock: Prepare the configuration for change by locking it.
- Edit: Edit the configuration with appropriate XML.
- Commit the configuration.
- Unlock the configuration.
Part B: SNMP based management
B.1. Lecture Module 2: ASN.1 and BER
SNMP - Simple Network Management Protocol
SMI - Structure of Management Information
Defines SNMP specific ASN.1 syntax and semantics, nodes in the Internet Management tree, the OBJECT-TYPE Macro and mechanism to define Indexes.
A collection of related MIBs that are implemented as a whole in a managed system.
SNMP version 1 and 2 is prone to the following security threats:
- Modification of Information
- Reordering of message fragments (to modify meaning)
This is resolved in SNMPv3 by implementing the following security services:
- Data integrity
- Data origin authentication
- Prevention of redirection, delay and replay
RDF - Resource Description Framework
RDF is a framework for describing resources on the web. It is designed to be read and understood by computers, and written in XML. RDF is a W3C recommendation.
Example RDF document:
<?xml version="1.0"?> <RDF> <Description about="http://www.w4schools.com/rdf"> <author>Kris. K. Larsen</author> <homepage>http://www.w4schools.com</homepage> </Description> </RDF>
CIM - Common Information Model
Consists of three main components:
- CIM Specification
- CIM Schema
- CIM Extension Schema
Defines details for integration with other models, as well as syntax and rules and the CIM metaschema.
Defines the actual model descriptions for systems, applications, local area networks (LANs) and devices. It consists of the Core Model and the Common Models.