Optical Core Networks Management protocols

Optical Core Networks Management protocols
Place for logos of authors’ institutions Optical Core Networks Management protocols Barbara Martini, Scuola Superiore Sant’Anna, Fabio Baroncelli, Scuola Superiore Sant’Anna,

Outline Basic foundations of Network Management:
Overview on Management classification Motivation for Network Management Management paradigm Terminology and Basic Concept Standardization activity Description on the Management Information Simple Network Management Protocol (SNMP) Revision: date

Management Classification (1)
Provider structure (processes, services, policies) Service management Applications Applications Applications Information management data data System management From a technical point of view, we have 4 management concepts/category. They represents different aspects of the ICT management and are actually closely tied/related. The term Service Management is responsible for service delivery, such as order management, inventory management, provisioning and activation, network topology management and maintenance, and stability/performance diagnostics of communication service providers and their networks. A service management system automates manual operations of the network, delivery services, and support, making these areas more efficient and error-free. Information management is the handling of information acquired by one or many disparate sources in a way that optimizes access by all who have a share in that information or a right to that information. This involves the applications that handle this information. System management refers to enterprise-wide of distributed computers end-systems. System management is strongly influenced by network initiatives in telecommunication. The most known system management system are IBM Tivoli Framework, MS System Management Server, HP Open View, CA Unicenter. Network management refer to the communication resources that enable nodes to communicate. Workstation Host PC Printer Communication Network (hub, bridge, router, multiplexer,switch) Network management Revision: date

Management Classification (2)
Information & System Management LAN LAN LAN MAN MAN ISP WAN Gestione di rete di backbone (operatore di TLC): Apparati FR,ATM,SDH, WDM: usano protocolli proprietari per il trasporto di informazioni e gestione/segnalazione in WAN IP e GbitEth sempre piu’ usati, dunque gestione piu’ open source soprattutto agli edge della rete di dorsale (MAN/WAN) Gestione di rete locale (LAN system administrator): IP, ethernet, WLAN Linux sempre piu’ usato per gestire reti e servizi Service Management MAN Network management: Backbone network (WAN,MAN) Local Area Network (LAN) LAN Revision: date

The importance of Network management: use case
Data Server Low performance Application TCP IP LAN Eth Application TCP IP LAN FDDI User Throughput reduction FDDI Ethernet Sinchronism loss on E3 frame Consider for example a failure that consist in the loss of synchronism on the clock for E3 frame in a mux PCM. The synchronism loss on E3 traffic flow produces the loss of E3 frames. As a conseguence E1 frames are lost and the flow at 64kbps carried by E1 frames are corrupted. Therefore a huge amount of TCP connections will be affected by a high bit error rate. Since TCP uses a sliding window mechanism, this means a strong reduction of throughput on all carried TCP connections. This cause a tangible delay on application program and if the application are sensible to this delay, a huge amount of application transaction will be aborted. The user perceive low performance and protest against the system administrator. Since the Data Service is ok, the complain is reported to the local network administratore (LAN) that is ok, so the problem is reported to the backbone network operator that must pay for the violetion of the agreement. The importance of network managemant lies in the necessity to respect the traffic agreement and guarantee the cash receipts and payment from customer (business objectives) ATM SDH/WDM 64kbps PDH/SDH E1 MUX PCM E3/E1 E3 34Mbps Revision: date

Network management: basic concept
GUI LAN LAN WAN/MAN Support for: Remote investigation Real-time supervision Automatic data processing Planning future evolution Serve per capire da remoto cosa e’ successo ad un network system (both at a level of network element and network segment LAN/WAN). Management: set of procedure and tools that guarantees the effective and efficient use of a (communication) system and its resources according to the business objectives A network management system is a bundle of software designed to significantly improve network efficiency and productivity. Although the network engineer can perform manually the same services that a newtork management system can, it is preferable that the software perform these routine tasks, thus freeing up the engineer to work on sophisticated network issues (strategy definition, staff organization). Because a network management system is expected to accomplish many tasks simultaneously, it must have enough computing power. A common platform employed is a desktop workstation that uses a graphical window interface. Network management is the process of controlling a complex data network so as to maximize its efficiency and productivity Target: Increase the network reliability Minimize the network costs Improve network performance and QoS Plan future network evolution LAN LAN Revision: date

Management Activity Loop
Monitor status and receive event reports Interpret policy and make decisions Perform management operations Monitor the system to obtain up-to-date status information and to receive event reports Interpret the overall policy pertaining to the goals or requirements of the organization that owns the system in order to make decisions about what behaviour is required from the system Perform control actions on the system resources to change their behaviour and implement the management decisions Revision: date

Network Management definition
Network management is a service that employs a variety of tools, applications, and devices to assist human network managers in the control and maintenance of a network. Network management includes the deployment, integration and coordination of the hardware, software and human elements to monitor, test, poll, configure, analyze, evaluate the network resources to meet the real-time, operational performance and QoS requirements at a reasonable cost. The combination of hardware and software used to monitor and administer a network is called Network Management System (NMS) A Network Management System (NMS) is a combination of hardware and software used to monitor and administer a network. Network Management The execution of the set of functions required for controlling, planning, allocating, deploying, coordinating, and monitoring the resources of a network, including performing functions such as initial network planning, frequency allocation, predetermined traffic routing to support load balancing, cryptographic key distribution authorization, configuration management, fault management, security management, performance management, and accounting management. to be an end in itself Revision: date

Management System Requirements (1)
Guarantee the availability of the newtork operation Service maintenance (availability, response time) need to face with technological changes Security of the services through the control of security components Human mistake prevention and bottleneck identification/recovery Automatic or semiautomatic reaction on operation anomalies: Real-time configuration modification in case of error Activation of redundant components in case of error Dynamic reactions to changes on the network and environment: Changes regarding applications, users, components, services or fees Dynamic adaptation of the available transmission bandwidth according to request originated by the management system Target: Increase the network reliability Minimize the network costs Improve network performance and QoS Plan future network evolution Revision: date

Management System Requirements (2)
Network control: Collection and (compressed) representation of relevant network information Definition and maintenance of a database of network configurations When applicable, centralization of the control over peripherals and implemented functions (central management console) Integration of management procedures on heterogeneous environment Improvement of network administrators work conditions: Identify and implement gradual automation of management functions Good integration of tools into the existing operational sequences Progress through standardization: transition of existing, often proprietary, solutions in a standardized environment 8 by deri Revision: date

Functional Areas (OSI Management)
Fault Management Configuration management Performance management Security management Accounting Management Fault management is the process of locating problems, or faults on the data network. Configuration management is the process of finding and setting up critical device in the network. The problem here is a congruent configuration of different systems the inter-work each-others. The goal of performance management is to measure and make available various aspects of network performance so that internetwork performance can be maintained at an acceptable level. Security management is the process of controlling access to information on the data network. This is a very important question in this period. Accounting management involves tracking each individual and group user’s utilization of network resources so that engineer can better ensure users are provided the quantity of resources they need. The accounting is the driving force in network management because ensure incoming to the company. Revision: date

Managed Object (1) Management System Real telephone Managed Object
Attributes Operations Behaviour Notifications Push button receiver Warning: telephone equipment is operational but no voice is heard line represented as sees Management System Real telephone Managed Object Control, co-ordination and monitoring of network resources take place via the manipulation from Managed Objects (MO)s MO are an abstract representation of a network resource, both physical and logical The boundary of a management object specifies which details are accessible to a management system and which ones are shielded (black box) MO is an abstract representation of a physical (router, telephone, coffee machine) or logical (communication protocol) network entitiy The boundary of a management object specifies which details are accessible to a management system and which ones are shielded (black box). A managed object is caracterized by some attributes which represent its properties, its characteristics that need to be visible from the outside, the operations (methods) to which the MO responds, its behaviour and events (notifications) the MO emits asynchronously. The line can be free, engaged, working… Revision: date

Managed Object (2) Attributes:
describe the state/condition of managed objects can change when the condition of the real object changes can be manipulated by means of management operation Operations: make it possible to access a managed object. the number and type of operation influence the object performance and complexity Behaviour: determines the semantics and interaction with the real resources is normally defined using text in plain english Notifications the quantity and type of the messages, which can be generated by predefined situations by a managed object when specific situation occur Manageable resources are modelled by managed objects at different level of abstraction. Managed object encapsulate teh underlying resource and offer access interface at the boundary. The management aspects of entities such as network element or distributed applications are modeled trrough cluster of managed objects, seen collectively across a management interface. The management interface is defined thought as “exported” by applications in agent role and “imported” by applications in manager role. Manager applications access managed objects across interfaces in order to implement management policies. Typical opeartion are: get, set, create and delete Revision: date

Managed Object (3) “A managed object is the abstracted view of a resource that present its properties as seen by (and for the purpose of) management (ISO )” A managed object may represent a relationship between several resources. Multiple managed objects may represent a single resources to provide different abstract view of the resource for different management purpose. Managed objects do not necessarily correspond to objects, as one knows from object-oriented programming. Simple variables correspond to the MOs in the Internet Management A managed object may represent a relationship between several resources, or a combination of resources such as an entire network. A single resources may be represented by multiple managed objects which provide different abstract view of the resource for different management purpose. Revision: date

Manager-Agent paradigm
operation (get,set) notification Manager Agent MO MO Management Communication protocol int’l object MO In the Manager-Agent paradigm, an application process called “manager” which reside in managing system and application process called “agent” which reside in the managed system. Manager and agent co-operate via standard protocols within a shared schema of management knowledge. The managed objects are system and network resources that are subject to management. Management activities are effected through the interrogation and manipulation of the managed objects. Using the management services expressed as messages and the messaging protocols, a manager can direct an agent to perform an operation on a managed object for which it is responsible. Such operation may involves setting an attribute, retrieving an attribute value or performing some action and returning the result. In addition the agent may spontaneously generate notification messages to the manager indicating the occurrence of events in the managed objects under its control. Although the protocols themselves make no assuptions about the asymmetry or otherwise of the relationships between the communicating application processes, the manager is considered to have the superior role and the agent correspondingly the subordinate role. Note that manager and agent applications contain other internal objects that support the implementation of relevant functionality. There are not visible externally, so they are depicted with dotted lines. Network Management System Managed Device Management Interface Revision: date

Agent role Implements the MOs by accessing the real resources
Receives requests from a manager, processes them and transmits appropriate responses Dispatches notifications about important changes in the MOs Protects MOs against unauthorised accesses using access control rules and communication authentication with the partner The manager/agent paradigm is a concept for the hierarchical exchange of management information between systems. A managing system assume the role of “manager” for the purpose of issuing directives and receiving notifications. A managed system assumes the role of “agent” for hte purpose of carrlying out directives and emitting notifications. A system that plays the role of “manager” to a lower system may simultaneously play the role of agent to a higher level system, allowing for a cascaded management hierarchy Revision: date

Manager role Exercises control: it controls functions hence it is the crucial instance Starts up management operations by appropriate protocol operations for the manipulation of MOs Receives messages from agents and passes them (for handling) to appropriate applications Revision: date

Management Protocol MOs Manager Agent
Implements access to distant managed objects by encoding management data that is then secure during the transfer Several protocols can be used for the implementation of the defined services The service primitive and the appropriate protocols operations influence considerably the efficiency and the complexity of the management system MOs Algorithm for the solution of management problem CMIP, SNMP Management protocol -- A management protocol is used to convey management information between agents and NMSs. SNMP is the Internet community's de facto standard management protocol. Mngm Prot Mngm Prot OSI layer 7 Communication protocol Manager Revision: date Agent

Management Information Base (MIB)
MO MIB Management Information Base (MIB) The collection of MOs is stored in a specific data base, called Managment Information Base (MIB) A MIB should be known both to the agent and the manager It represents a sort of “shared knowledge” of network resources The set of managed object classes and instances under the control of an agent is called MIB. The MIB is an abstraction of network resources, properties and states for the purpose of management. A managed object may represent a relationship between several resources, or a combination of resources such as an entire network. A single resources may be represented by multiple managed objects which provide different abstract view of the resource for different management purpose. Agent alias the implementer that make resource information available. Revision: date

Management Information Structure
Structure of the management information: Defines the rules of the description of Managed Objects Identification and designation of MOs Composition of MOs Behaviour of MOs Relations to other MOs Possible operations and internal messages of the MOs Definition of the datatypes, structure and syntaxt for the description of the MOs The quantity of the descriptions of MOs in accordance with these rules defines the Management Information Base (MIB) Revision: date

Network Management Architecture
Network Management System NMS Manager Management Protocol Management Data Managed Network Most network management architectures use the same basic structure and set of relationships. End stations (managed devices), such as computer systems and other network devices, run software that enables them to send alerts when they recognize problems (for example, when one or more user-determined thresholds are exceeded). Upon receiving these alerts, management entities are programmed to react by executing one, several, or a group of actions, including operator notification, event logging, system shutdown, and automatic attempts at system repair. Management entities also can poll end stations to check the values of certain variables. Polling can be automatic or user-initiated, but agents in the managed devices respond to all polls. Agents are software modules that first compile information about the managed devices in which they reside, then store this information in a management database, and finally provide it (proactively or reactively) to management entities within network management systems (NMSs) via a network management protocol. Well-known network management protocols include the Simple Network Management Protocol (SNMP) and Common Management Information Protocol (CMIP). Management proxies are entities that provide management information on behalf of other entities. Figure 6-1 depicts a typical network management architecture. Agent Agent Agent MIB MIB MIB Managed Devices Revision: date

Management Network Data Network
The management network is to be considered a logically separated network from data network Management Interface Rete di gestione separata dalla rete gestita Management Data Management Network Revision: date

Target of the Current Developments
Implementation of integrated management systems which cover all the requirements for the management of heterogeneous networks and systems Good expandiblity and adaptability to the local network environment Good support during the automation of management flows and conversion of management guidelines Protection of the management against attacks of unauthorized people Scalability of both the size of the network and increasing demanding requests of the management systems Open interfaces to the existing infrastructure and their integration into operational sequences. Revision: date

Infrastructure for network management
Management Interface Management Information Base (MIB) Network Management System MIB Agent Managed Device Manager MIB Agent Managed Device Network Management Protocol MIB Agent Managed Device Managed devices represented as a set of managed objects whose data is gathered into a MIB Revision: date

Management of the Internet
"Internet" refers to a set of devices that is logically linked together by a globally unique address space based on the Internet Protocol (IP) is able to support communications using the Transmission Control Protocol/Internet Protocol (TCP/IP) suite These devices contain information (like parameters and statistics) that need to be managed about their: Configuration Running conditions Healthy neighborhoods Revision: date

Management of the Internet
Network Browser Packet Router Route Webserver Software The global Internet has thousands of networks Revision: date

Requirements Measurement tools to quickly, accurately and automatically identify Internet communication problems A common network management model for managing the TCP/IP protocols and the Internet devices as well Web services are in their early days, they have a steep learning curve, the schemas and not mature Revision: date

Why is internet management so important?
End users & network managers should be able to identify & track internet problems End users need to verify the service level agreement (SLA) stipulated with the Internet Service Provider (ISP) The ISP should be able to set expectations: Deciding which links need upgrading Deciding where to place network devices (e.g., routers) Forecast how well an application (e.g., VoIP) will work Revision: date

Why is internet management so difficult?
Internet's evolution is a composition of independently developed and deployed protocols, technologies, and core applications The phone connection oriented model (Poisson distributions of session length etc.) does not work for Internet traffic Internet management is not in the priority list of the vendors: Resources/skill focus on more interesting an profitable issues Tools lacking or inadequate Implementations poor & not fully tested with new releases For privacy issues, the ISPs worried about providing access to their core network making results public Revision: date

LAN vs WAN Managing the LAN Managing the WAN
Network admin has control so: Can read information from devices Can passively sniff traffic (e.g., using Ethereal) Know the routes between devices (manually for small networks, automated for large networks) Managing the WAN No admin control, unless you are an ISP Can’t read information out of routers May not be able to sniff/trace traffic due to privacy/security concerns Don’t know route details between points Revision: date

Passive vs. Active Traffic Monitoring
Active Monitoring Injects extra artificial traffic provides explicit control on the generation of packets for measurement scenarios testing what you want, when you need it Passive Monitoring does not inject extra traffic, measures real traffic parameters using: Probe Devices that capture/watch packets as they pass (e.g., Router, switch, sniffer) Network device that records network status information Generally we use both approaches, e.g. start active measurement and look at passively Revision: date

Active Monitoring tools: examples
Ping = for monitoring the destination reachability Traceroute = for tracing a path Pingroute = Combines ping & traceroute, Pathchar, Pipechar/abing = for path characterization Iperf = for measuring the network throughput Ping Traceroute Source Destination Revision: date

Passive Monitoring tools
Hardware probes = (e.g., Sniffer, NetScout) can be stand-alone or remotely access from a central management station Software probes = (e.g., snoop, tcpdump) Flow measurement = (e.g., netramet, Netflow) Revision: date

The ICMP Protocol Internet Control Message Protocol (ICMP), documented in RFC 792, is a protocol that uses IP for out-of-band messages related to network operation Since ICMP uses IP, ICMP packet delivery is unreliable, so hosts cannot count on receiving ICMP packets for any network problem. Some of ICMP's functions are to: Announce network errors, such as a host unreachable due to any failure. Announce network congestion. When a router begins buffering too many packets, due to an inability to transmit them as fast as they are being received, it will generate ICMP Source Quench messages. Directed at the sender, these messages should cause the rate of packet transmission to be slowed. Assist Troubleshooting. ICMP supports an Echo function, which just sends a packet on a round-trip between two hosts. Ping, a common network management tool, is based on this feature. Ping will transmit a series of packets, measuring average round-trip times and computing loss percentages. Announce Timeouts. If an IP packet's TTL field drops to zero, the router discarding the packet will often generate an ICMP packet announcing this fact. Revision: date

Ping Ping is common network management tool based on ICMP:
Client sends ICMP echo request, server sends reply Client measures average round-trip times and computes loss percentages Client can specify the number of data bytes transmitted, can puts timestamp in data bytes and can compares timestamp with time when echo comes back Revision: date

Ping (2) “Host Unreachable” Error Message Router “Echo” “Echo Reply”
ICMP Message IP Header Revision: date

Ping example Remote host Repeat count Summary
syrup:/home$ ping -n 6 thumper.bellcore.com PING thumper.bellcore.com ( ): 64 data bytes 72 bytes from : icmp_seq=0 ttl=240 time=641.8 ms 72 bytes from : icmp_seq=2 ttl=240 time= ms 72 bytes from : icmp_seq=3 ttl=240 time= ms 72 bytes from : icmp_seq=4 ttl=240 time=758.5 ms 72 bytes from : icmp_seq=5 ttl=240 time=482.1 ms --- thumper.bellcore.com ping statistics packets transmitted, 5 packets received, 16% packet loss round-trip min/avg/max = 482.1/880.5/ ms Repeat count Summary Revision: date

Traceroute Traceroute is an ICMP utility that traces a packet from local to a remote host, showing how many hops the packet requires to reach the remote host and how long each hop takes. If you're visiting a Web site and pages are appearing slowly, you can use traceroute to figure out where the longest delays are occurring. TraceRoute maps network routes by sending packets with small Time-to-Live (TTL) values and watching the ICMP timeout announcements. Revision: date

Lost packet or router ignores
Traceroute example Max hops Remote host -m 20 lhr.comsats.net.pk traceroute to lhr.comsats.net.pk ( ), 20 hops max, 40 byte packets 1 RTR-CORE1.SLAC.Stanford.EDU ( ) ms 2 RTR-MSFC-DMZ.SLAC.Stanford.EDU ( ) ms 3 ESNET-A-GATEWAY.SLAC.Stanford.EDU ( ) ms 4 snv-slac.es.net ( ) ms 5 nyc-snv.es.net ( ) ms 6 nynap-nyc.es.net ( ) ms 7 gin-nyy-bbl.teleglobe.net ( ) ms 8 if bb5.NewYork.Teleglobe.net ( ) ms 9 if bb6.NewYork.Teleglobe.net ( ) ms ( ) ms ( ) ms 12 islamabad-gw2.comsats.net.pk ( ) ms 13 * 14 lhr.comsats.net.pk ( ) ms No response: Lost packet or router ignores Revision: date

Pingroute Pingroute = Ping + Traceroute
It runs traceroute, then ping each founded router n times Pingroute helps identify the route where the problem starts to occur Revision: date

Path characterization
sends multiple packets of varying sizes to each router along route measures minimum response time plot min RTT vs packet size to get bandwidth calculate differences to get individual hop characteristics measures for each hop: BW, queuing, delay/hop can take a long time Pipechar/abing Also sends back-to-back packets and measures separation on return Much faster Finds bottleneck Bottleneck Min spacing At bottleneck Spacing preserved On higher speed links Revision: date

Iperf Iperf measures the network throughput
Client generates & sends UDP or TCP packets Server receives receives packets Can select port, maximum window size, port , duration, Mbytes to send etc. Client/server communicate packets seen etc. Reports on throughput Requires sever to be installed at remote site, i.e. friendly administrators or logon account and password Revision: date

Iperf example 3 parallel streams Max window size TCP port Remote host
-p w 512K -P 3 -c sunstats.cern.ch Client connecting to sunstats.cern.ch, TCP port 5008 TCP window size: 512 KByte [ 6] local port connected with port 5008 [ 5] local port connected with port 5008 [ 4] local port connected with port 5008 [ ID] Interval Transfer Bandwidth [ 4] sec MBytes Mbits/sec [ 5] sec MBytes Mbits/sec [ 6] sec MBytes Mbits/sec Total throughput =3*15.3Mbits/s = 45.9Mbits/s Remote host Revision: date

Questions OK the monitoring of the traffic but…
how about the management of the network devices? Revision: date

The fundamental of internet management
Internet Architecture Board (IAB) released RFC 1052 entitled "IAB Recommendations for the Development of Internet Network Management Standards" in April 1988. This RFC explains that the network management must : Be as large as possible. Have the wider diversity of implementation as possible. Have the wider diversity of administration/management as possible. Cover as many protocol layer as possible. Revision: date

The SNMP The Simple Network Management Protocol (SNMP) is an application layer protocol that facilitates the exchange of management information between network devices. SNMP is part of the Transmission Control Protocol/Internet Protocol (TCP/IP) suite. Nowadays SNMP is not limited to TCP/IP devices SNMP enables network administrators to manage network performance, find and solve network problems, and plan for network growth. Revision: date

SNMP RFCs The following RFCs are the first documents dealing with SNMP published in 1988 : RFC Structure and Identification of Management Information for TCP/IP-based internets RFC Management Information Base for Network Management of TCP/IP-based internets RFC A Simple Network Management Protocol (SNMP) Revision: date

SNMP nodes An SNMP nodes is a device of an SNMP managed network. There are different types of SNMP nodes: Managed nodes = Typically runs an agent process that services requests from a management node Management nodes = Typically a workstation running some network management & monitoring software Not manageable nodes = A node may not support SNMP, but may be manageable by SNMP through a proxy agent running on another machine Nodes can be both managed nodes and a management node at the same time Revision: date

SNMP Components SNMP agent is a software that runs on network nodes (host, router, printer, or others) and that maintains information in a database about its configuration and current state Management Information Bases (MIBs) is the database of the managed information An SNMP manager is an application program that contacts an SNMP agent to query or modify the database at the agent. SNMP protocol is the application layer protocol used by SNMP agents and managers to send and receive data. Revision: date

SNMP Components MIB MIB MIB Revision: date

SNMP Manager-Agent interaction
MIB SNMP MESSAGES UDP UDP IP IP ETHERNET ETHERNET Revision: date

Ports & UDP SNMP uses User Datagram Protocol (UDP) as the transport mechanism for SNMP messages Ethernet Frame IP Packet SNMP Message CRC UDP Datagram Like FTP, SNMP uses two standard ports to operate: UDP Port SNMP Messages UDP Port SNMP Trap Messages Revision: date

Advantages of using SNMP
Standardized Universally supported Extendible Portable Allows distributed management access Lightweight protocol Revision: date

SNMP and Functional Areas of Network Management
Configuration Management - inventory, configuration, provisioning Fault Management - reactive and proactive network fault management Performance Management - # of packets dropped, timeouts, collisions, CRC errors Security Management – configuration of security policy Accounting Management - cost management and chargeback assessment Asset Management - statistics of equipment, facility, and administration personnel Planning Management - analysis of trends to help justify a network upgrade or bandwidth increase Revision: date

SNMP supporting languages
Abstract Syntax Notation One (ASN.1) = It is used to define the format (syntax) of SNMP messages and managed objects (MIB modules) using an unambiguous data description format Structure of Management Information (SMI) = It defines the rules for describing management information, using ASN.1. specifies the format used for defining managed objects that are accessed via the SNMP protocol Basic Encoding Rules (BER) = It is used to encode the SNMP messages into a format suitable for transmission across a network Revision: date

SNMP Protocol Stack Revision: date

SNMP Basic Commands Managed devices are monitored and controlled using four basic SNMP commands: The Get command is used by an NMS to monitor managed devices. The NMS examines different variables that are maintained by managed devices. The Set command is used by an NMS to control managed devices. The NMS changes the values of variables stored within managed devices. The Trap command is used by managed devices to asynchronously report events to the NMS. When certain types of events occur, a managed device sends a trap to the NMS. Traversal operations are used by the NMS to determine which variables a managed device supports and to sequentially gather information in variable tables, such as a routing table. Revision: date

SNMP versions Three versions of SNMP exist:
SNMP version 1 (SNMPv1) 1990 SNMP version 2 (SNMPv2) 1996 = same features of SNMPv1 but it offers enhancements, such as additional protocol operations. SNMP version 3 (SNMPv3) 2002 = augments the original SNMPv1 and the SNMPv2 specifications with additional security and administration capabilities. All versions are still used today Many SNMP agents and managers support all three versions of the protocol. Revision: date

SNMPv1 SNMP version 1 (SNMPv1) is the initial implementation of the SNMP protocol. It is described in RFC 1157 and functions within the specifications of the Structure of Management Information (SMI). SNMPv1 operates over protocols such as User Datagram Protocol (UDP), Internet Protocol (IP), OSI Connectionless Network Service (CLNS), AppleTalk Datagram-Delivery Protocol (DDP), and Novell Internet Packet Exchange (IPX). SNMPv1 is widely used and is the de facto network-management protocol in the Internet community. Revision: date

SNMPv1 limitations Authentication is inadequate:
Password (community string) placed in clear in SNMP messages MIB variables must be polled separately, i.e. entire MIB cannot be fetched with single command SNMPv2 and v3 attempt to address these and other limitations Despite limitations, SNMP has been a huge success Provides device and link utilization (byte, packets) and errors Lot of facilities/tools built around SNMP to provide reports for sites Revision: date

SNMPv2 SNMP version 2 (SNMPv2) is an evolution of the initial version, SNMPv1. As with SNMPv1, SNMPv2 functions within the specifications of the Structure of Management Information (SMI). SNMPv2 offers a number of improvements to SNMPv1, including additional protocol operations. Revision: date

SNMPv3 The new features of SNMPv3 include: Security
Authentication Privacy authorisation Access control Administrative Framework naming of entities people and policies user names and key management notification destinations proxy relationships remotely configurable via SNMP operations Revision: date

SNMP Interoperability
SNMPv2 is incompatible with SNMPv1 in two key areas: message formats protocol operations SNMPv2 messages use different header and protocol data unit (PDU) formats than SNMPv1 messages. SNMPv2 also uses two protocol operations that are not specified in SNMPv1. RFC 1908 defines two possible SNMPv1/v2 coexistence strategies: proxy agents and bilingual network-management systems. Revision: date

Optical Core Networks Management protocols

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