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7/28/2019 08.OSPF Planning and Design Process
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Cisco CCNP ROUTE TrainingInstructor: Joe Rinehart, CCIE #14256
OSPF Planning andDesign Process
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
In This Lesson:
Unique Characteristics of OSPF
When OSPF is the Best Design Choice
OSPF Planning Methodology
Verification Plan for Implementation
Implementation Steps
Transitioning to OSPF from Another Protocol
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Unique Characteristics of OSPF
1. Brief History of OSPF
2. Link-State Protocol Characteristics
3. Unique OSPF Features
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Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Brief History of OSPFNeed for More Robust IGP
IETF Formed OSPF Working Group in1988 to Replace RIP:
Network size limitations
Inability to choose higher bandwidthinterfaces/links
Derived from Several Sources
Bolt, Beranek, and Newman's (BBN)SPF algorithm for ARPANET (1978)
Radia Perlmans research on faulttolerant broadcast of routing data(1988)
BBNs Area Routing Work (1986)
Early Version of OSI IS-IS ProtocolJohn Moy, OSPF:Anatomy of an Internet Routing Protocol(Reading Mass: Addison-Wesley, 1998)
1987
1989
1991
1993
1995
1997
OSPF Working
Group Formed
OSPF V1PublishedFirst OSPF
Interoperability
Testing
OSPF Demo at
Interop 91
OSPF V2
Published
OSPF
Recommended
IGP
OSPF V2
UpdatedInternet Adopts
CIDRCrypto
Added
OSPF V2
Updated
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Link-State Protocol Characteristics
Formal Neighbor Relationships
Hello packets sent for neighbor discoveryand maintenance
Database synchronization and exchange
Active tracking of neighbor state
Link State (Topology) Database
Constructed of information about activepaths (links) in the network
All routers contain copies of the database
Update Process
Once database is built only changes sent When there is a change it is flooded
Dijkstra algorithm used for calculation
Network 1 Network 2
Network 3 Network 4
XLink
Outage
R1
R3
R2
R4
R3 LSA
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Link-State Protocol Characteristics
Rapid Convergence
Link-state database and path calculationprocess is rapid and very efficient
Loop avoidance inherent in the protocol
Higher CPU and memory utilization
Complexity
Greater amount of effort required inplanning and design process
Configuration requires more work
Vastly greater depth in routing logic andcomputation process
Network 1 Network 2
Network 3 Network 4
XLink
Outage
R1
R3
R2
R4
R3 LSA
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Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Unique OSPF Features
Formal Hierarchy
Ability to segment the network intomultiple section called areas
Area 0 (Backbone) is required and allother areas must directly connect to it
Flooding and route calculation is
restricted within each area
Route Summarization
Support for aggregation/supernetting
Configurable on a per-area basis
Industry Standard Protocol
Open designates OSPF as standard
Implemented by every equipment vendor
Network 1 Network 2
Network 3 Network 4
XLink
Outage
R1
R3
R2
R4
R3 LSA
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Unique OSPF Features
Cost as Basis for Route Selection
Bandwidth of interface assigned a cost
Lowest cumulative cost to destinationnetwork makes for best route
Different Network Types Supported
Broadcast (e.g., Ethernet LAN)
Non-Broadcast
Point-to-Point
Point to Multipoint (Non)Broadcast
Neighbor Types
Designated Router (DR): Single peer onbroadcast network
Backup DR: Secondary peer
Network 1 Network 2
Network 3 Network 4
XLink
Outage
R1
R3
R2
R4
R3 LSA
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
When OSPF is the Best Design Choice
1. In Multi-Vendor Routing Environment
2. For Scalability in Large Networks
3. Design Principles for OSPF
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Cisco CCNP ROUTE Training
OSPF Planning and Design Process
When OSPF is the Best Design Choice
In Multi-Vendor Routing Environment
Routing and/or Layer 3 Switches Can Befrom ANY Equipment Manufacturer
OSPF V2 (IPV4) and V3 (IPV6)assumed
Open standard
Vendor Support List (Partial)
Cisco
Avaya
Juniper
HP
Adtran
Enterasys
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
When OSPF is the Best Design Choice
For Scalability in Large Networks
OSPF can experience stuck-in-activeconditions in very large topologies
Link State Database synchronization and
flooding behavior limited to areas
Address summarization in areas
Fewer SPF calculations using areas
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
When OSPF is the Best Design Choice
Design Principles for OSPF
Multi-Access Network Peering
Routers establish one peeringrelationship (DR/BDR)
Select and configure DR/BDR usingthe priority command
Serial Interface Bandwidth
OSPF also assumes 1.544 Mbps forany serial interface
Use the bandwidth command to setthe actual value
Remember that frame-relay isinherently a non-broadcast medium
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Cisco CCNP ROUTE Training
OSPF Planning and Design Process
When OSPF is the Best Design Choice
Design Principles for OSPF
Limit Number of Routers per Area
Older documentation recommends 50
Depends on a variety of factors:
Type of area (stub, NSSA, etc.)
Number of external LSAs
How well other areas are/can besummarized
CPU and memory available on thedevices
Media type (LAN/Frame-Relay,
etc.)
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
When OSPF is the Best Design Choice
Design Principles for OSPF
Limit Number of Area Border Routers
ABRs keep separate databases foreach area connected
Also depends on a variety of factors
Can be avoided by allocatingconnectivity to additional devices
Goal is not to overload the ABR
Summarize Addressing When Possible
Design and use IP addressing that
can be summarizedDeploy address summarization
whenever practical and possible
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
When OSPF is the Best Design Choice
Design Principles for OSPF
Carefully Choose Area Designs
Avoid placing devices in area 0 unlesscritical to overall network operations
Use redundant links betweenbackbone routers whenever possible
Maintain consistency in designation oflabeling for areas
Create a template for areas
Avoid the use of virtual-links
Try to anticipate growth in the designprocess
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Cisco CCNP ROUTE Training
OSPF Planning and Design Process
OSPF Planning Methodology
1. General Network Design Principles
2. High Level Design
3. Pilot/Proof of Concept Testing
4. Review and Verification Process
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
OSPF Planning Methodology
General Network Design Principles
Start with REQUIREMENTS
Know what the expectations are
Be able to clearly explain theexpected outcomes
Gather all of the facts
Perform a physical site inspection
Account for power, cabling, anddevice placement
Know the availability and timeline of
WAN circuitsAccount for any existing devices that
require support
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
OSPF Planning Methodology
General Network Design Principles
Document allASSUMPTIONS
Financial (capital budget/operationalcosts)
Who is responsible for what
Expected time for design,implementation and testing
Other people/organizations involved
Ask questions for confirmation
Get everything in writing and signedas confirmation
Develop contingency plans
Develop and stick to a project plan
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Cisco CCNP ROUTE Training
OSPF Planning and Design Process
OSPF Planning Methodology
High Level Design
Create High-Level Diagram(s)
Site Locations
Proposed equipment
VLAN/LAN IP Addressing
Wide Area Connection Links
Routing protocol domains
Develop a Bill of Materials (BOM)
Equipment (type and quantity)
Lead time/delivery dates
SMARTnet Maintenance
Staging logistics
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
OSPF Planning Methodology
High Level Design
System-Wide IP Addressing Allocation
Subnet, mask(s), equipment IPs
Consistency in addressing
Database of addresses and locations
Reserved and unused rangesdocumented
Ability to summarize contiguousranges of addresses
Track usage/decommissioning of
addresses within the pool(s) Turn the high-level plan into detailed
plans after approvals
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
OSPF Planning Methodology
Pilot/Proof of Concept Testing
When Implementing New Technologies, aPilot or Proof of Concept Trial is Advisable
Technology: Wireless, Unified
Communications, etc.
Devices: New models/types of LANswitches, routers, etc.
Acquisition: Business merger,telecommuter program, etc.
Protocol: Change of routingprotocol, etc.
Process: Changes the way thecompany is doing business (e.g.,replacing card payment systems)
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Cisco CCNP ROUTE Training
OSPF Planning and Design Process
OSPF Planning Methodology
Pilot/Proof of Concept Testing
Map Out a Testing Environment thatRepresents the Larger Project
Scope: Subset of the number andtype(s) of sites
Devices: Same type(s) of devices to
be used in larger implementation
Staging: Create a lab-centricminiature version of the network
Testing Plan: Create a plan that willtest the limits and outcomes
Reporting: Codify results andconclusions for use in the largerimplementation (lessons learned)
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
OSPF Planning Methodology
Review and Verification Process
Involve as many competent people in theprocess of reviewing your designs anddocumentation
Peers: Those in your department
Experts: Individuals whose skills andexperience are greater than your own
Critics: Carefully chosen peoplewhose evaluation is likely to beaccurate
Superiors: Direct supervisor or
department heads
Others: Additional reviewers asneeded
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Implementation Steps
1. Detailed Project Plan
2. Device-Specific Configurations
3. Verification Steps
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Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Implementation Steps
Detailed Project Plan
Basic Document Format
Identification of stakeholders
Identification of roles andresponsibilities
Timelines and milestones
Communication plan
Account for power, cabling, anddevice placement
Implementation plan(s)
Expected outcomes
Criteria for completion
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Implementation Steps
Device-Specific Configurations
Routers/Layer 3 Devices
Hostnames (adhering to standards)
Interface configurations
Security configurations
EIGRP Routing configuration elements
Usernames/Passwords/TACACS
Network Time Protocol
SNMP/Syslog
WAN configurations
Device access
Advanced configurations
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Implementation Steps
Device-Specific Configurations
Layer 2/3 Switches
Hostnames (adhering to standards)
SVI Interface configurations
Security configurations
Usernames/Passwords/TACACS
Network Time Protocol
SNMP/Syslog
VLAN configurations
Device access
Advanced configurations
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Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Verification Steps
Commands Verifying Configuration(s)
General Connectivity/Functionality
show ip interface brief
show cdp neighbors
show environment all
show diag
show inventory
OSPF Routing
show ip protocols
show ip ospf interfaces
show ip ospf neighbor
show ip ospf database
show ip route ospf
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Verification Steps
Commands Verifying Configuration(s)
General Connectivity/Functionality
debug ip packet
debug interface
OSPF Routing
debug ip ospf adjacency
debug ip ospf events
debug ip ospf hello
debug ip ospf spf
debug ip ospf lsa-generation
debug ip ospf packet
debug ip ospf flood
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Transitioning to OSPF from Another Protocol
1. In a New (Greenfield) Environment
2. In an Existing Network
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Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Transitioning to OSPF from Another Protocol
In a New (Greenfield) Environment
Assumptions
Not necessarily a first-time networkinstallation
May involve new equipment and/ornew telecommunications circuits
Probably maintaining identical LANaddressing
Other routing protocols in use in all orpart of the existing network
Static routing
EIGRP
RIP
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Transitioning to OSPF from Another Protocol
In a New (Greenfield) Environment
Transition Process
Stage new equipment with OSPF
Connect only a small test network foranalysis purposes
Have full configuration available forday of transition
Have full testing plan codified
Schedule outage window after hours
Migrate area 0 First
Disconnect old devices and swap withnew OSPF devices
Execute test plan and certify network
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Transitioning to OSPF from Another Protocol
In an Existing Network
Assumptions
Existing equipment will host OSPF
No new circuits or IP addressing
Involves a hot cut to implement
Requires several key elements:
Transition plan
Testing plan
Roll-back plan in the event ofissues
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Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Transitioning to OSPF from Another Protocol
In a New (Greenfield) Environment
Transition Process
Configure OSPF with a higheradministrative distance (suggesteddistance of224)
Ability to establish OSPF neighbor
relationships and peering
May stage dummy IP addresses toserve as testing points
Schedule an outage window afterhours
At transition time set administrativedistance back to 110
Execute test plan and certify network
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
Key Terms You Should Know
Link-State Class of Interior Gateway Protocol that relies on alldevices having an identical understanding of the network (links)
DR/BDR Designated Router/Backup Designated Router, theprimary/secondary devices that all devices on a multi-access
establish a neighbor relationship with
Area In OSPF, a partitioned section of the network in which allrouters maintain an identical copy of the link state database
Area 0Also referred to as the backbone area, the OSPF arearequired area through which all traffic must transit
Roll-Back Plan Contingency plan for restoring the network toits original state following an unsuccessful transition attempt
Greenfield Term used to describe installation of a brand-newnetwork infrastructure in a given location
Cisco CCNP ROUTE Training
OSPF Planning and Design Process
What We Covered
Unique Characteristics of OSPF
When OSPF is the Best Design Choice
OSPF Planning Methodology
Verification Plan for Implementation
Implementation Steps
Transitioning to OSPF from Another Protocol