The%20Network%20Management%20Problem%20Chapter%203

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The Network Management ProblemChapter 3

• Network Management, MIBs, and MPLS
• Stephen B. Morris

Rodrigo Iglesias de Aliaga
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Overview

• Network Operators problems with the growth of
  traffic types and volumes.
• Operational increase due to Multiple NMS growth.
• There is a strong need to reduce the cost of
  ownership and improve the return on investment
  (ROI) for network equipment.

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Overview

• Automated, flow-through actions are required for
  network management operations.
• Provisioning
• Detecting faults
• Checking (and verifying) performance
• Billing/accounting
• Initiating repairs or network upgrades
• Maintaining the network inventory

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Bringing the Managed Data to the Code

• Managed objects reside on many SNMP agent hosts.
• Copies of managed objects reside on SNMP
  management systems.
• Changes in agent data may have to be regularly
  reconciled with the management system copy.

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Bringing the Managed Data to the Code

• Components of an NMS

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Bringing the Managed Data to the Code

• The Quality of an NMS is inversely proportional
  to the gap between its picture of the network and
  the actual state of the underlying network- the
  smaller the gap, the better the NMS.
• As managed NES become more complex, an extra
  burden is placed on the management system.

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Scalability

• Todays Network is Tomorrows NE
• Scalability is one of the biggest problems facing
  modern networking.
• A scalability problem occurs when an increase in
  the number of instances of a given managed object
  in the network necessitates a compensating,
  proportional resource increase inside the
  management system.

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Layer 2 VPN Scalability

• Scalability Problems tend to arise in situations
  of proportional growth.
• The N2 Problem
• When the number of layer 2 virtual circuits
  rquired is proportional to the square of the
  number of sites.
• Anything in networking that grows at the rate of
  N2 tends to give rise to a problem of scale.
• As the number of sites gets bigger, the N2 term
  is more significant than the other terms.

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The N2 problem
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The N2 problem

• Layer 3 VPNs
• Layer 3 VPNs provide a much more scalable
  solution because the number of connections
  required is proportional to a number of sites,
  not the square of the number of sites.
• Layer 3 VPNs avoid the need for a full mesh
  between all of the customer edge routers by
  providing these features
• A layer 3 core
• Overlapping IP address range across the connected
  sites (if separate organizations use the same VPN
  service)
• Multiple routing table instances in the provider
  edge routers

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Virtual Circuit Status Monitoring

• Scalability problems arise when the MIB table
  entries become very large due to NMS attempts to
  read all MIB table entries at the same time.

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MIB Scalability

• Network operators and their users demand more
• Bandwidth
• Faster Networks
• Bigger Devices
• Scalability concerns are growing because routers
  and switches are routinely expected to support
  the creation of millions of virtual circuits.

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Creating LSPs in an MPLS network
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Other Enterprise Network Scalability Issues

• Scalability concerns also affect enterprise
  networks in these areas
• Storage Solutions
• Adding, deleting, modifying, and monitoring SANs
• Administration of Firewalls
• Rules for permitting or blocking packet transit
• Routers
• Access control lists and static routes
• Security Managements
• Encryption keys, biometrics facilities, and
  password control
• Application Management

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Light Reading Trials

• Internet core routers from Cisco, Juniper,
  Charlottes Networks, and Foundry Networks were
  stress-tested during 2001 using these tests
• MPLS throughput
• Latency
• IP throughput at OC-48
• IP throughput at OC-192

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Large NEs

• Advantages of the deployment of much bigger
  device
• They reduce the number of devices required,
  saving central office (CO) space and reducing
  cooling and power requirements.
• They may help to reduce cabling by aggregating
  links.
• They offer richer feature set.
• Disadvantages
• They are harder to manage.
• They potentially generate vast amounts of
  management data.
• They are a possible single point of failure if
  not back up.

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Expensive (and Scarce) Development Skill Sets

• Building management systems for the devices of
  today and tomorrow is increasingly difficult.
• General migration to a Layer 3 infrastructure is
  another reason for the widening gap between
  available development skills and required product
  features.
• The need for customers to see rapid ROI for all
  infrastructural purchases

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Expensive (and Scarce) Development Skill Sets

• A different approach is needed for developing
  management systems.
• Acquiring skills like these would positively
  enhance the development process.
• A solution mindset
• Distributed, creative problem solving
• Taking ownership
• Acquiring domain expertise
• Embracing short development cycles
• Minimizing code changes
• Strong testing capability

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A Solution Mindset

• Solutions have a number of characteristics
• Clear economic value
• Fulfillment of important requirements
• Resolution of one or more end-user problems

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A Solution Mindset
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Distributed, Creative Problem Solving

• Software Bugs
• NE Bugs (Hard to identify)
• Performance Bottlenecks in FCAPS applications due
  to congestion on the network.
• Client Applications crashing from time to time
• MIB Table Corruption
• SNMP Agent Exceptions

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Distributed, Creative Problem Solving

• Tools available to solve these problems
• UML support packages
• Java/C/SDL products
• Version control
• Debuggers

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Taking Ownership

• A broad task can be ring-fenced by a small group
  of developers who take responsibility for design,
  development, and delivery.
• Traditional development boundaries are removed.
• No more pure GUI, backend, or database
  developers.
• All NMS software developers should strive to
  extend their portfolio of skills to achieve this.
• Institutional memory relates to individual
  developers with key knowledge of product
  infrastructure.

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Acquiring Domain Expertise

• Domain expertise represents a range of detailed
  knowledge
• IP/MPLS that can be readily applied to the needs
  of an organization.

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Acquiring Domain Expertise

• Knowledge include areas such us
• Layer 2 and layer 3 traffic engineering
• Layer 2 and layer 3 QoS
• Network Management
• Convergence of legacy technologies into IP
• Backward and forward compatibility of new
  technologies
• MPLS

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Linked Overviews

• ATM Linked Overview
• IP Linked Overview
• Embracing Short Development Cycles
• Minimizing Code Changes

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Elements of NMS Development

• NMS Developments
• Using a browser-based GUI
• Developer wants to check that the software
  executed the correct actions
• During provisioning, developer verifies Java
• Database is updated by the management system code
• Verifying that the correct set of managed objects
  was written to the NE

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Elements of NMS Development

• Data Analysis
• Upgrade considerations
• UML, Java, and Object-Oriented Development
• Class Design for Major NMS Features
• GUI Development
• Middleware Using CORBA-Based Products
• Insulating Applications from Low-Level Code

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Expensive (and Scarce) Operational Skill Sets

• The growing complexity of networks is pointing to
  increasingly scarce operational skills
• Multiservice Switches
• Enterprise network typically want to
• Reduce the payback period for new purchases
• Maintain and expand existing network services
• Reduce operational costs associated with multiple
  networks
• Telephony
• LAN

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Expensive (and Scarce) Operational Skill Sets

• Multiservice Switches
• MPLS provides a way of filling these needs in
  conjunction with multiservice switches
• ATM
• FR
• TDM
• IP

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MPLS Second Chunk

• Managed objects of MPLS
• Explicit Route Objects
• Resource blocks
• Tunnels and LSPs
• In-segments
• Out-segments
• Cross-connects
• Routing Protocols
• Signaling Protocols
• Label operations
• Traffic Engineering
• QoS

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Explicit Route Objects

• An ERO is a of layer 3 address hops inside an
  MPLS cloud
• Describes a list of MPLS nodes through which a
  tunnel passes.
• EROs are used by signaling protocols to create
  tunnels

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Resource Blocks

• MPLS permits the reservation of resources in the
  network.
• Resource blocks provide a means for recording the
  bandwidth settings
• Resource blocks include
• Maximum reserved bandwidth
• Maximum traffic burst size
• Packet length

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Tunnels and LSPs

• MPLS-encapsulated packets enter the tunnel, pass
  across the appropiaye path, and exhibit three
  important characteristics
• Forwarding is based on MPLS label rather than IP
  header
• Resource usage is fixed, based on those rederved
  at the time of connection creation
• The path taken by the traffic is constrained by
  the path chosen in advance by the user.

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In-Segments and Out-Segments

• In-segments on an MPLS node represent the point
  of ingress for traffic
• Out-segments represent the point of egress for
  traffic

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Cross-Connects

• MPLS node uses the cross-connect settings to
  decide how to switch traffic between the segments
• Connection Types
• Point-to-Point
• Point-to-Multipoint
• Multipoint-to-Point

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Routing Protocols

• MPLS incorporates standard IP routing protocols
  such as OSPF, IS-IS and BGP4

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Signaling Protocols

• LSPs and tunnels can be achieved either manually
  or via signaling
• Signaled connections have
• Resource Reserved
• Labels Distributed
• Paths selected by protocols
• RSVP-TE
• LDP

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Label Operations

• MPLS-labeled traffic is forwarded based on its
  encapsulated value
• The operations that can be executed against
  labels are
• Lookup
• Swap
• Pop
• Push

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MPLS Encapsulation

• The MPLS Encapsulation specifies four reserved
  label values
• 0-IPv4 explicit null that signals the receiving
  node to pop the label and execute an IP lookup
• 1-Router alert that indicates to the receiving
  node to examine the packet more closely (rather
  than simply forwarding it)
• 2-IPv6 explicit null
• 3-Implicit null that signals the receiving node
  to pop the label and execute an IP lookup

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Qos and Traffic Engineering

• LAN Bandwidth can be increased as needed using
  switches
• Excess bandwidth helps avoid congestion
• Traffic Engineering is set to become a mandatory
  element of converged layer 3 enterprise networks.

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QoS

• There are three approaches that can be adopted
  for providing different levels of network service
• Best effort (as provided by the Internet)
• Fine granularity QoS (Integrated Services
  IntServ)
• Coarse granularity QoS (Differentiated Services
  DiffServ)

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IP Header
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MPLS and Scalability

• This table can include millions of rows
• It is not practical to try to read or write an
  object of this size using SNMP
• Unfortunately, it might be necessary if a
  network is being initially commissioned or
  rebalanced after adding new hardware

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MPLS and Scalability
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MPLS and Scalability
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Summary

• Bringing managed data and code together is one of
  the central foundations of computing and network
  management
• Designers of management systems need rarified
  skills set that matches the range of technologies
  embedded in NEs and networks Liberal use of
  standards documents and linked overviews are some
  important tools for tackling the complexity of
  system development, managed object derivation,
  and definition.
• Networks must increasingly support a growing
  range of traffic types. (Traffic Engineering and
  QoS handling in Layer 2 and Layer 3 Networks).