Large Enterprise Networks Chapter 1

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Large Enterprise Networks Chapter 1

• Network Management, MIBs, and MPLS
• Stephen B. MorrisStudent Paul L. Martin III
  Tre

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Overview

• Chapter 1 presents a general overview of modern
  enterprise network management
• Importance of Network Management
• Introduction to Network Management Pyramid
• Goals of Network Management Systems (NMSs)
• Understanding Simple Network Management Protocol
  (SNMP)

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Large Enterprise Networks

• What is a Business ENTERPRISE?
• A business enterprise is a collection of
  organizations and people formed to create and
  deliver products to customers
• What is an NETWORK?
• A group of stations (computers, telephones, or
  other devices) connected by communications
  facilities for exchanging information. Connection
  can be permanent, via cable, or temporary,
  through telephone or other communications links.
  The transmission medium can be physical (ie fiber
  optic cable) or wireless (e.g. satellite).

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Enterprise Networks Defined

• Two Main Categories
• Enterprise Network
• A networking system that allows communication and
  resource sharing among all of a company's
  business functions and workers. This can even
  include the company's suppliers and
  distributors.3
• Service Provider
• SPs generate contractually repeating revenues
  for the services delivered to their customers
  over a network, typically the Internet. These
  services must be commercially available to the
  general population. The price for such services
  must include the actual delivery of the service
  including accommodations for the cost of the
  infrastructure to deliver the service (e.g.
  hardware, software, data center, labor, IP).4

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Main Goals of the Enterprise Network

• Two Main Focus Areas
• Provide or improve business processes
• Save the organization money rather than act as a
  revenue source

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Enterprise Network Characteristics

• Large in Size (Equipment Personnel)
• Can be Geographically Separated
• Can maintain Legacy Equipment
• Generally Hard to Manage
• Network Scalability affects Network
  Manageability Network Usability
• Generally owned by one organization

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Enterprise Network Characteristics (Cont)

• Many users simultaneously supported
• Wide Range of Multi-vendor devices
• Network Elements can contain other intelligent
  devices
• Individual N.Es can provide multiple services
• Specialized Servers provide advanced services
  (I.e., SAN servers)
• All network services are used as essential
  business process components by organizational
  personnel

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Enterprise Network Functional Components

• Network Management Challenges include
• Complex apps services
• Ever-changing apps services
• Geographically-dispersed locationsand Personnel

All Bold text boxes provide some type of service
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Enterprise Networks Advantages

• Centralized computing facilitates data sharing
• Centralized computing facilitates data backups
• Centralized management of software resources
• Network Authentication/Authorization can be
  enforced
• Network Administrators can perform remote
  software installations
• Expensive devices (laser printers, scanners,
  etc.,) can be shared
• Users can access their files from any workstation
  

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Enterprise Networks Disadvantages

• Expensive to build, operate, maintain, and
  upgrade
• Require skilled maintenance support personnel
• Data Voice traffic traditionally kept separate
  now merging

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What is Network Management?

• A set of activities (e.g. network monitoring,
  gathering and analyzing the statistics, adjusting
  network configuration) performed in order to
  increase the network performance and
  availability5
• The process and techniques of remotely or locally
  monitoring and configuring networks. Under the
  OSI model network management takes account of
  five key areas configuration management, fault
  management, performance management, accounting
  management, and security management6 (FCAPS)

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What is Network Management?

• Network management provides the means to keep
  network up and running in as orderly a fashion as
  possible.
• Functional areas required for effective network
  management include FCAPS
• Fault Detecting network errors/break downs
• Configuration The set up and fine tuning of s/w
  h/w into an existing infrastructure
• Accounting Financial responsibilities such as
  paying SPs, verifying charges
• Performance Ensuring the network is operating
  to standards/expectations
• Evaluate current and future performance metrics
• Security Protect network vs. hackers, or
  malicious activity

Figure Taken from the Telecommunications
Management Network architecture definition
created by the International TelecommunicationsUn
ion in 1988. Source http//www.luteus.biz/Down
load/LoriotPro_Doc/V4/LoriotProV4Doc/N14Management
_Goals/FCAPS_EN.htmFaultManagement
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What is Network Management?

• BML - Business Management Layer
• Manage the overall business, gaining return on
  investment, market share, employee satisfaction,
  community and governmental goal.
• SML - Service Management Layer
• Manage the service offered to customer or
  internal users, meeting customer service level,
  service quality, cost and time-to-market
  objectives
• NML - Network Management Layer
• Manage the network and systems that deliver those
  services, capacity, diversity, and congestion

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What is Network Management?

• EML - Element Management Layer
• Mange the elements comprising the networks and
  systems
• NEL - Network Element Layer
• Switches, routers, transmission, distribution
  systems

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The Management System Pyramid

• OSS Operations Support System
• System that handles workflows, managementinventor
  y details, capacity planning,and repair
  functions for SPs
• OSS used by the business support system
• OSS uses underlying NMS to communicatewith lower
  level devices
• Expensive to deploy and develop
• Approx. Cost 1M
• Example AceComm is an OSS vendor

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The Management System Pyramid

• NMS Network Management System
• Computer based SW application suite thatmanages
  N.Es
• Provides abstractions (signaling links, virtual
  connections, etc), fault networkconfiguration,
  retrieve performance billing data, execute
  provisioning,security, script management, audit
  trails
• Network-wide oversight usage
• Oversight over many N.Es (not just one)
• Uses EMS to communicate with N.Es
• Approx. Cost 10K
• Example Altiris can be used as an NMS

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The Management System Pyramid

• EMS Element Management Systems
• Manages one or more of a specific type of NEs
• EMS allows the user to manage all the features
  of each NE individually
• Specific functions include
• S/W upload/download
• Configuration DB backup/restore
• Alarm processing storage
• Approx. Cost 1K

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Key Difference (NMS vs EMS)

• Easy to confuse NMS and EMS roles/functions
• Key general difference is
• NMS operations involve more than one NE
  simultaneously
• EMS operations focus on a single NE
• The guiding principle is the same for any
  OSS/NMS/EMS
• Make using the object of attention easier to use

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Why is Network Management Important?

• Maintains Network Availability
• Network keeps running
• Law of Five Nines The definition of system
  uptime or availability as 99.999, or an approx.
  downtime of 5 min/yr
• Good Network Management facilities assist in all
  the lifecycle stages
• Overall Operational Costs are reduced
• Manage multiple incompatible management systems
• SNMPv3 uses MIBs for network management of data
  objects

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Why Use Network Management?

• Comprehensive Network Oversight
• Management systems maintain entire network
  oversight - N.Es typically do not
• Record Audit Trail Logging
• An NMS maintains useful records audit trails of
  past configuration actions
• Unsupported Management Protocols
• If N.Es dont support SNMP, then a NMS can
  facilitate a superior CLI
• Network-wide service implementation
• NMS can facilitate network wide service like
  (I.e., traffic engineering, QoS, planning,
  modeling, backup/restore)

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Why Use Network Management?

• Fast Fault Rectification
• NMS enable fast access to faults.
• Some network faults can only be handled by an
  NMS
• Rebalancing Facilitation
• NMS assist in rebalancing networks after new
  hardware is added
• Network-wide Object Support
• Management system can provide network wide
  object support for service profile

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Common Network Management Challenges

• Backward Compatibility
• Rare to experience forkliftupgrades
• General expectation rich mixture of old new
  N.Es
• Result Complex set of MIBs deployed across
  network
• Multiplicity of Management Systems
• Lack of Standards-based management system
  consolidation

Older N.Es
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Advantages of Standards-Based Consolidation

• Fewer simpler user management interfaces
• Reduced IT staff training time
• Fast fault identification problem resolution
• Easier integration of new hardware/software to
  overall infrastructure
• Management system can provide network wide object
  support for service profile (lessons learned
  case studies for future reference)

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The Manageability Factor

• For the number of reasons, not all NEs lend
  themselves to flexible, integrated, centralized
  management.
• This tends to add to the cost of ownership due to
  the following range of reasons
• The NE is a legacy device with proprietary
  management infrastructure
• The NE implements only SNMPv1 with support for
  set operations
• The NE implements only SNMPv1 without support for
  set (a set operations is an update to a
  network-resident manage object operations)
• The NE supports SNMPv3, but it has been poorly
  implemented
• The NE supports SNMP3 but has a number of low
  quality MIB modules
• An NE is considered to have good manageability if
  it supports a well implemented SNMPv3 agent and a
  high-quality MIB

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Operating Managing Large Networks

• Important Aspects of Network Management include
• Traffic-Management as of services/apps increase
• Measuring traffic levels and checking for network
  congestion
• Bandwidth Management
• Network N.Es Availability
• Network N.E Status Monitoring
• Discovery and Asset Inventory management
• Network Configuration
• VLAN setup, SAN volume setup,storage
  allocations, remote control software
• Service level agreement (SLA) reporting, SLA
  verification between an enterprise and SP
• Security control
• Resistance to attacks from both sides of the
  firewall
• Scalability
• handling increased numbers of users, traffic,
  NEs,
• Disaster recovery

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SNMP

• Layer 2, 3, and 2.5Ports and Interfaces

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Understanding OSI Layer 2 3

• To understand Network Management, one must have a
  thorough comprehension of OSI Layer 2 and Layer 3
• Layer 2 Data Link Layer
• Defines rules for sending/receiving data across a
  physical connection
• Examples ATM, Frame Relay, Ethernet Switch
• Layer 3 Network Layer
• Ensures packets of information reach destination
  across multiple point-to-point links
• Interconnected networks joined by routers
• Example Device IP Router

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Layers 2, 3, and 2.5

• Layer 2 Data Link Layer
• Layer 3 Network Layer
• Layer 2.5 has been used to categorize some
  protocols that operate between layer 2 and layer
  3.

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Layer 2, 3, and 2.5

• The primary protocols that SNMP implements
• User Datagram Protocol (UDP) and the
• Internet Protocol (IP)
• SNMP also requires Data Link Layer protocols
  (e.g. Ethernet, Token Ring) to implement the
  communication channel between manager and agent
• Data Link Layer
• Provides the means to transfer data between
  network entities and to detect and possibly
  correct errors that may occur in the Physical
  layer.
• The addressing scheme is physical which means
  that the addresses (MAC address) are hard-coded
  into the network cards at the time of manufacture

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MPLS on Layer 2.5

• Multiprotocol Label Switching
• A method used to increase the speed of network
  traffic flow by inserting information about a
  specific path the packet is taking en route to
  its destination.
• Saves the time needed for a router to look up the
  address for the next receiving node
• MPLS is multiprotocol in that it works with IP,
  ATM, and Frame Relay communications methods
• MPLS has some Quality of Service features that
  make it an attractive communications technique.
• Supplemental Link Click here

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How MPLS Works
Click here for full article
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MPLS Advantages/Disadvantages

• Advantages
• Can be deployed on routers
• Paths can be reserved before traffic arrives at
  the network
• Different QoS options can be applied
• Ex Higher QoS can be reserved for VoIP lower
  for e-mail
• Traditional IP routing protocols can be used
• Ex OSPF, IS-IS, BGP4
• Congested route problems can be reduced through
  dynamic traffic monitoring and engineering
• Disadvantage
• All nodes in the path must run MPLS protocols
  additional burden

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Ports and Interfaces

• Terms Ports and Interfaces often used
  interchangeably, which is not necessarily the
  case
• Ports underlying hardware entities
• Example ATM or Ethernet ports
• Interfaces Exist at a higher abstraction layer
• Configured to run on top of ports
• Referred to as logical ports
• Interface examples include
• Routing such as OSPF, IS-IS, BGB-4
• Signaling, such as RSVP-TE and LDP
• MPLS
• IP
• General Difference Ports work out of the box,
  interfaces must be configured

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SNMP

• Simple Network Management Protocol
• Providing Network Management Capability

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The Goal of a NMS

• The difference between the real-time network
  situation and the NMS picture of the network
  situation must be as small as possible
• Administrators constantly strive to know and/or
  be able to quickly find out what is going on with
  their network
• The purpose of NMSs and SNMP
• Help administrators stay on top of network
  operations, events, and faults

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What is SNMP?

• A protocol used by network hosts to
• Exchange information,
• Monitor and control network devices, and to
• Manage configurations, statistics collection,
  performance, and security used in the management
  of networks.
• SNMP network management is based on the client
  and server model
• Used almost exclusively in TCP/IP networks, but
  not limited to them
• SNMP facilitates communication between network
  devices

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What is SNMP?
An SNMP-Managed Network Consists of Managed
Devices, Agents, and NMSs
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What does SNMP do?

• Notify network administrators about network
  status through network notifications
• Events
• An indication from the network to the NMS of some
  item of interest
• EX User logging onto a NE via Command Line
  Interface (CLI)
• Faults
• An indication of a service-affecting network
  problem
• EX Communication line link failure
• Alarms
• An indication that a potentially
  service-affecting problem is about to occur
• EX Congestion threshold being exceeded

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Main SNMP Components

• Principal Components of SNMP are
• 1. Manager
• An application that performs the operational
  roles of generating requests to modify and
  retrieve management information, and receiving
  the requested information and trap-event reports
  that are generated by the SNMP agent
• 2. Agent
• An application that performs the operational role
  of receiving and processing requests, sending
  responses to the manager, and sending traps when
  an event occurs

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Main SNMP Components

• Four Principal Components of SNMP are
• 3. Management Information Base (MIB)
• The set of parameters (database) that an SNMP
  management station can query or set in the SNMP
  agent of a networked device (e.g, router).
• The unique identifier of each managed object
  includes the type (such as counter, string,
  gauge, or address), access level (such as
  read/write), size restrictions, and range
  information of the object.
• 4. Protocol Data Units (PDUs)
• A data object exchanged by protocol machines
  (e.g. SNMP agents) consisting of both protocol
  control information and user data

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SNMP Manager Role (Explained)

• SNMP managers are the entities that interact with
  the agent
• Establishing obtaining the values of MBI
  objects instances on agent
• Receiving notifications from agents
• Exchanging messages with other managers

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SNMP Manager Role (Explained)

• Facilities offered by management systems are
• FCAP
• A centralized database
• Reporting Capabilities
• Support for many simultaneous client users
• Topology discovery
• Full featured, multi-level Graphical User
  Interface (GUI) representing the managed network

Click here to see Fujitsus NETSMART 500Network
Element Manager
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SNMP Agent Role (Explained)

• SNMP agent are the entities that reside on manage
  devices.
• Agent are the workhorses of management provide
  the following functionality
• Implementing and maintaining MIB objects
• Responding to management operations such as
  requests
• Generating trap inform notifications
• Security Implementation
• Set Access Policy for External Managers

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SNMP Agent Role (Explained)
The SNMP agent listens on UDP port 161
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SNMP MIBs (Explained)

• Each management station or agent in an
  SNMP-managed network maintains a local database
  of information relevant to network management,
  known as the management information base (MIB)
• An SNMP-compliant MIB
• Contains definitions and information about the
  properties of managed resources and the services
  that the agents support.
• Managed objects/Management variables
• The manageable features of resources
• A management station gets and sets objects in the
  MIB, and an agent notifies the management station
  of significant but unsolicited events called traps

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SNMP MIBs (Explained)

• MIBs
• The most crucial/important NMS component
• MIBs contain data definitions for managed objects
• SNMP managers agents exchange object instances
  using SNMP protocol
• Are Plain-text files
• MIBs are compiled into agent source code -gt
  executable file
• Textual Conventions
• MIB refinements (similar to programming language
  data types or classes in Java or C)

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SNMP MIB (Explained)

• The following keywords are used to define a MIB
  object
• Syntax
• Defines the abstract data structure corresponding
  to the object type
• Access
• Defines whether the object value may only be
  retrieved but not modified (read-only) or whether
  it may also be modified (read-write)
• Description
• Contains a textual definition of the object type.
  The definition provides all semantic definitions
  necessary for interpretation it typically
  contains information of the sort that would be
  communicated in any ASN.1 commentary annotations
  associated with the object

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SNMP MIB (Explained)

• Object Identifer (OID) used by the management
  station to request the object's value from the
  agent
• OID - a sequence of integers that uniquely
  identifies a managed object by defining a path to
  that object through a tree-like structure called
  the OID tree or registration tree
• When an SNMP agent needs to access a specific
  managed object, it traverses the OID tree to find
  the object.

Lexicographic Ordering
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SNMP MIB Lexicographic Ordering
The OID serves as a uniquename that represents a
nodein the tree-based structure All objects can
be traced fromthe root in a process
calledwalking the MIB. During a walk, each
branch of the MIB is traversed from leftto
right, starting at the root
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SNMP PDUs (Explained)

• SNMP uses very simple messaging protocol
• Three basic commands
• Fetch (GET)
• Store (SET)
• Notification/Inform Message
• Each SNMP message has the format
• Version Number
• Community Name - kind of a password
• One or more SNMP PDUs - assuming trivial
  authentication

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SNMP PDUs (Explained)

• SNMPv1 originally defined six PDUs
• These PDUs have been redefined over the years
• The current SNMP Framework categorizes the PDUs
  into different classes.

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SNMP Get PDU
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SNMP Get-Next PDU
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SNMP Set Protocol
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SNMP Trap PDU
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SNMPv1

• SNMPv1 is probably best known for its relative
  simplicity
• Much more complicated than following versions
• SNMPv1 message format is simple
  straight-forward

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SNMPv2

• Certain issues with SNMPv1 were noticed areas
  for improvement identified
• MIB object definitions
• Protocol operations
• security
• Several versions of SNMPv2 several message
  formats
• PDU format is the same for all the SNMPv2 types,
• The overall message format differs for each
  variant.

Click here to see SNMPv2 Message Format
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SNMPv3

• Created in the late 1990s
• SNMP version 3 resolved the problems that
  occurred with the many different variations of
  SNMPv2
• Adopts many components created in SNMPv2
  including
• SNMPv2 protocol operations,
• PDU types and
• PDU format.
• Significant changes made in SNMPv3 include
• more flexible way of defining security methods
  and parameters allowing the coexistence of
  multiple security techniques

Click here to see SNMPv3 Message Format
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SNMP Management Systems Agents

• SNMP manager
• Any computer that sends queries for IP-related
  information to a managed computer
• SNMP manager can send a request to an SNMP agent
  to change a configuration value
• SNMP agent
• Any computer or other network device that
  monitors and responds to queries from SNMP
  managers
• Can send a trap message to the manager when
  specified events (I.e., system reboots, illegal
  access notification)

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SNMP Manager/Agent Communication
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Chapter 1 Summary

• Large Enterprise Networks require good enterprise
  management from both people/administrators and
  systematic/technical components
• The goals of enterprise networks
• Make organizational personnel more productive
• Save the organization money (not act as a revenue
  producer)
• The goal of network management
• Maintain network availability
• You cant achieve the goals of enterprise
  networks if you cant use them.

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Chapter 1 Summary

• The Simple Network Management Protocol has become
  the de facto standard for internetwork management
• It is a simple solution,
• Requires little code to implement,
• Vendors can easily build SNMP agents to their
  products
• SNMP is extensible - allowing vendors to easily
  add network management functions to their
  existing products
• SNMP separates the management architecture from
  the architecture of the hardware devices, which
• Broadens the base of multi-vendor support

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Supplemental Materials

• General Network Management
• Article Network Management as Core Competency
  Computerworld, 20 March 2006
• Article Cisco Moves to Support Network
  Management Computerworld, 12 December 2005
• MPLS
• Article Building Large Metro Ethernets
  requires MPLSConverge! Network Digest, 24
  October 2004
• SNMP
• Article Is it time to re-engineer
  SNMPNetworkworld, 22 March 2004