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The Network Management Problem
Chapter 3
Network Management, MIBs, and MPLS
Stephen B. Morris
Rodrigo Iglesias de Aliaga
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Overview
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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
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Automated, flow-through actions are required for
network management operations.
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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
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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
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Components of an NMS
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Bringing the Managed Data to the Code
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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
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Today’s Network is Tomorrow’s NE
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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
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Scalability Problems tend to arise in situations of
proportional growth.
The N2 Problem
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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
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Layer 3 VPNs
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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:
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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
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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
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Network operators and their users demand more:
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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
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Scalability concerns also affect enterprise networks in
these areas:
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Storage Solutions
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Administration of Firewalls
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Access control lists and static routes
Security Managements
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Rules for permitting or blocking packet transit
Routers
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Adding, deleting, modifying, and monitoring SANs
Encryption keys, biometrics facilities, and password control
Application Management
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Light Reading Trials
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Internet core routers from Cisco, Juniper, Charlotte’s
Networks, and Foundry Networks were stress-tested
during 2001 using these tests
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MPLS throughput
Latency
IP throughput at OC-48
IP throughput at OC-192
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Large NEs
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Advantages of the deployment of much bigger device
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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
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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
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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
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A different approach is needed for developing
management systems.
Acquiring skills like these would positively enhance the
development process.
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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
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Solutions have a number of characteristics
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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
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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
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Tools available to solve these problems
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UML support packages
Java/C++/SDL products
Version control
Debuggers
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Taking Ownership
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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.
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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
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Domain expertise represents a range of detailed
knowledge
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IP/MPLS that can be readily applied to the needs of an
organization.
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Acquiring Domain Expertise
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Knowledge include areas such us:
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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
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MPLS
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Linked Overviews
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ATM Linked Overview
IP Linked Overview
Embracing Short Development Cycles
Minimizing Code Changes
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Elements of NMS Development
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NMS Developments
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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
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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
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The growing complexity of networks is pointing to
increasingly scarce operational skills
Multiservice Switches
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Enterprise network typically want to:
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Reduce the payback period for new purchases
Maintain and expand existing network services
Reduce operational costs associated with multiple networks
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Telephony
LAN
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Expensive (and Scarce) Operational
Skill Sets
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Multiservice Switches
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MPLS provides a way of filling these needs in conjunction with
multiservice switches
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ATM
FR
TDM
IP
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MPLS: Second Chunk
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Managed objects of MPLS
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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
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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
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MPLS permits the reservation of resources in the
network.
Resource blocks provide a means for recording the
bandwidth settings
Resource blocks include
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Maximum reserved bandwidth
Maximum traffic burst size
Packet length
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Tunnels and LSPs
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MPLS-encapsulated packets enter the tunnel, pass
across the appropiaye path, and exhibit three important
characteristics
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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
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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
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MPLS node uses the cross-connect settings to decide
how to switch traffic between the segments
Connection Types
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Point-to-Point
Point-to-Multipoint
Multipoint-to-Point
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Routing Protocols
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MPLS incorporates standard IP routing protocols such as
OSPF, IS-IS and BGP4
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Signaling Protocols
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LSPs and tunnels can be achieved either manually or via
signaling
Signaled connections have
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Resource Reserved
Labels Distributed
Paths selected by protocols
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RSVP-TE
LDP
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Label Operations
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MPLS-labeled traffic is forwarded based on its
encapsulated value
The operations that can be executed against labels are
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Lookup
Swap
Pop
Push
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MPLS Encapsulation
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The MPLS Encapsulation specifies four reserved label
values
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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
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LAN Bandwidth can be increased as needed using
switches
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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
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There are three approaches that can be adopted for
providing different levels of network service
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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
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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
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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).
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