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1ISP/IXP Workshops © 1999, Cisco Systems, Inc.
Introduction to OSPFIntroduction to OSPFIntroduction to OSPF
ISP/IXP WorkshopsISP/IXP WorkshopsISP/IXP Workshops
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2ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
AgendaAgendaAgenda
• OSPF Primer
• OSPF in Service Provider Networks
• OSPF BCP - Adding Networks
• OSPF Command Summary
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3ISP/IXP Workshops © 1999, Cisco Systems, Inc.
OSPF PrimerOSPF PrimerOSPF Primer
3ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
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4ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
OSPFOSPFOSPF
• Open ShortestPath First
• Link state or SPFtechnology
• Developed by OSPFworking group ofIETF (RFC 1247)
• Designed for TCP/IPInternet environment
• Fast convergence
• Variable-lengthsubnet masks
• Discontiguoussubnets
• No periodic updates
• Route authentication
• Delivered two yearsafter IGRP
• OSPF standarddescribed in RFC2328
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5ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Link StateLink State
Topology Information IsKept in a DatabaseSeparate from the
Routing Table
AA
BB
CC
22
1313
1313
ZZ
XX
X’s Link State
ZZ
XX
YYQQ
Z’s Link State
Q’s Link State
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6ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Link State RoutingLink State Routing
• Neighbour discovery
• Constructing an LSP
• Distribute LSP
• Compute routes
• On network failure
New LSPs flooded
All routers recompute routing tables
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7ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
FDDIDual Ring
Low Bandwidth UtilisationLow Bandwidth Utilisation
• Only changes propagated
• Multicast on multi-access broadcastnetworks
R1
LSA
XLSA
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8ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
FDDI Dual Ring
FDDI Dual Ring
Optimal Path UtilisationOptimal Path Utilisation
N1
N2 N3
N4
N5R1
R2
R3
R4
Cost = 1 Cost = 1
Cost = 10
Cost = 10
The optimal path is determined by thesum of the interface costs
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9ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Fast ConvergenceFast Convergence
• Detection Plus LSA/SPF
XR1 R3
R2
N2
Alternate Path
Primary Path
N1
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10ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Fast ConvergenceFast Convergence
• Finding a new route
LSA flooded throughout area
Acknowledgement based
Topology databasesynchronised
Each router derives routingtable to destination networks
LSA
XR1
N1
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11ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Utilises IP Multicast forUtilises IP Multicast forSending/Receiving UpdatesSending/Receiving Updates
• Broadcast networksDR and BDR —> AllSPFRouters (224.0.0.5)
All other routers —> AllDRRouters (224.0.0.6)
• Hello packets sent to AllSPFRouters(Unicast on point-to-point and virtuallinks)
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12ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
OSPF AreasOSPF Areas
• Group of contiguoushosts and networks
• Per area topologicaldatabase
Invisible outside the area
Reduction in routing traffic
• Backbone areacontiguous
All other areas must beconnected to the backbone
• Virtual Links
Area 1Area 4
Area 0Backbone Area
Area 2 Area 3
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13ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Classification of RoutersClassification of Routers
• Internal Router (IR)
• Area Border Router(ABR)
• Backbone Router (BR)
• Autonomous SystemBorder Router (ASBR)
Area 1
IR/BRArea 0
Area 2 Area 3
IR
ABR/BR
To other AS
ASBR
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14ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
OSPF Route TypesOSPF Route Types
Intra-area Route
all routes inside an area
Inter-area Route
routes advertised from one areato another by an Area BorderRouter
External Route
routes imported into OSPF fromother protocol or static routes
Area 0Area 2 Area 3
ABR
To other AS
ASBR
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15ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Inter-Area RouteInter-Area RouteSummarisationSummarisation
• Prefix or all subnets
• Prefix or all networks
• ‘Area range’ command
1.A 1.B 1.C
FDDIDual Ring
R1 (ABR)
R2
Network1
Next HopR1
Network1.A1.B1.C
Next HopR1R1R1
With summarisation
Withoutsummarisation
BackboneArea 0
Area 1
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16ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
External RoutesExternal Routes
• Redistributed into OSPF
• Flooded unaltered throughout the AS
• OSPF supports two types of externalmetrics
Type 1 external metrics
Type 2 external metrics (Default)
RIPIGRPEIGRPBGPetc.
OSPF
Redistribute
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17ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
External RoutesExternal Routes
• Type 1 external metric: metrics are addedto the summarised internal link cost
NetworkN1N1
Type 11110
Next HopR2R3
Cost = 10
to N1External Cost = 1
to N1External Cost = 2R2
R3
R1
Cost = 8
Selected Route
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18ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
External RoutesExternal Routes
• Type 2 external metric: metrics are comparedwithout adding to the internal link cost
NetworkN1N1
Type 212
Next HopR2R3
Cost = 10
to N1External Cost = 1
to N1External Cost = 2R2
R3
R1
Cost = 8
Selected Route
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19ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Topology/Link State DatabaseTopology/Link State Database
• A router has a separate LS databasefor each area to which it belongs
• All routers belonging to the samearea have identical database
• SPF calculation is performed separatelyfor each area
• LSA flooding is bounded by area
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20ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Protocol FunctionalityProtocol Functionality
• Bringing up adjacencies
• LSA types
• Area classification
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21ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
The Hello ProtocolThe Hello Protocol
• Responsible for establishing and maintainingneighbour relationships
• Elects designated router on multi-accessnetworks
FDDIDual Ring
Hello
HelloHello
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22ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
The Hello PacketThe Hello Packet
• Router priority
• Hello interval
• Router deadinterval
• Network mask
• Options: T-bit, E-bit
• List of neighbours
FDDIDual Ring
Hello
HelloHello
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23ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Designated RouterDesignated Router
• One per multi-access network
Generates network links advertisements
Assists in database synchronization
Designated Router
Designated Router
BackupDesignated Router
BackupDesignated
Router
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24ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Designated Router by PriorityDesignated Router by Priority
• Configured priority (per interface)
• Else determined by highest router ID
Router ID is the loopback interface address, ifconfigured, otherwise the highest IP address
144.254.3.5
R2 Router ID = 131.108.3.3
131.108.3.2 131.108.3.3
R1 Router ID = 144.254.3.5
DR
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25ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Neighbouring StatesNeighbouring States
• 2-way
Router sees itself in other Hello packets
DR selected from neighbours in state2-way or greater
DR BDR
2-way
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26ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Neighbouring StatesNeighbouring States
• FullRouters are fully adjacent
Databases synchronised
Relationship to DR andBDR
DR BDR
Full
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27ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
When to Become AdjacentWhen to Become Adjacent
• Underlying network is point to point
• Underlying network type is virtual link
• The router itself is the designated router
• The router itself is the backup designatedrouter
• The neighbouring router is the designatedrouter
• The neighbouring router is the backupdesignated router
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28ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
LSAsLSAs Propagate Along Propagate AlongAdjacenciesAdjacencies
• LSAs acknowledged alongadjacencies
DR BDR
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29ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Routing Protocol PacketsRouting Protocol Packets
• Share a common protocol header
• Routing protocol packets are sent with typeof service (TOS) of 0
• Five types of OSPF routing protocol packets
Hello - packet type 1
Database description - packet type 2
Link-state request - packet type 3
Link-state update - packet type 4
Link-state acknowledgement - packet type 5
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30ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Different Types ofDifferent Types of LSAs LSAs
• Five distinct type of LSAs
Type 1 : Router LSA
Type 2 : Network LSA
Type 3 and 4: Summary LSA
Type 5 and 7: External LSA
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31ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Router LSA (Type 1)Router LSA (Type 1)
• Describes the state and cost of therouter’s links to the area
• All of the router’s links in an area must bedescribed in a single LSA
• Flooded throughout the particular areaand no more
• Router indicates whether it is an ASBR,ABR, or end point of virtual link
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32ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Network LSA (Type 2)Network LSA (Type 2)
• Generated for every transit broadcastand NBMA network
• Describes all the routers attached to thenetwork
• Only the designated router originatesthis LSA
• Flooded throughout the area and nomore
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33ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Summary LSA (Type 3 and 4)Summary LSA (Type 3 and 4)
• Describes the destination outside thearea but still in the AS
• Flooded throughout a single area
• Originated by an ABR
• Only intra-area routes are advertisedinto the backbone
• Type 4 is the information about theASBR
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34ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
External LSA (Type 5)External LSA (Type 5)
• Defines routes to destination externalto the AS
• Default route is also sent as external
• Two types of external LSA:
E1: Consider the total cost up to the externaldestination
E2: Considers only the cost of the outgoinginterface to the external destination
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35ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Not Summarised: Specific LinksNot Summarised: Specific Links
BackboneArea #0
External links
1.A
1.C
1.B
1.D
TokenRing
TokenRing
TokenRing
TokenRing
3.D
3.A
3.C
3.B
1.A1.B1.C1.D
3.A3.B3.C3.D
2.A2.B2.C
2.A
2.C
2.B
TokenRing
TokenRing
• Specific link LSA advertised out• Link state changes propagate out ASBR
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36ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Summarised: Summary LinksSummarised: Summary Links
BackboneArea #0
ASBR
External links
1.A
1.C
1.B
1.D
TokenRing
TokenRing
TokenRing
TokenRing
3.D
3.A
3.C
3.B
2.A
2.B
TokenRing
TokenRing
• Only summary LSA advertised out• Link state changes do not
propagate
1 3
2
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37ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
BackboneArea #0
External links
1.A
1.C
1.B
1.D
TokenRing
TokenRing
TokenRing
TokenRing
3.D
3.A
3.C
3.B
2.A
2.C
2.B
TokenRing
TokenRing
ASBR
Not Summarised: Specific LinksNot Summarised: Specific Links
2.A2.B2.C3.A3.B3.C3.D
1.A1.B1.C1.D3.A3.B3.C3.D
1.A1.B1.C1.D2.A2.B2.C
• Specific link LSA advertised in• Link state changes propagate in
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38ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Summarised: Summary LinksSummarised: Summary Links
BackboneArea #0
3.D
3.A
2.B
• Only summary LSA advertised in• Link state changes do not
propagate ASBR
External links
1.A
1.C
1.B
1.D
TokenRing
TokenRing
TokenRing
TokenRing
3.C
3.B
2.A
TokenRing
TokenRing
2,3
1,3
1,2
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39ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
TokenRing
TokenRing
TokenRing
TokenRing
Regular Area (Not a Stub)Regular Area (Not a Stub)
From area 1’s viewpoint
• Summary networks from other areas injected
• External networks injected, for examplenetwork X.1
ASBR
External Networks
1.A
1.C
1.B
1.DTokenRing
TokenRing
3.C
3.B
2.A
2,3
1,3
1,2X.1
X.1
X.1
X.1
2.D2.C
2.B
3.A
3.D
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40ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
TokenRing
TokenRing
TokenRing
TokenRing
Normal Stub AreaNormal Stub Area
From area 1’s viewpoint
• Summary networks from other areas injected
• Default network injected into the area - represents external links
• Default path to closest area border router
• Define all routers in the area as stubarea x stub command ASBR
External Networks
1.A
1.C
1.B
1.DTokenRing
TokenRing
3.C
3.B
2.A
2,3 & Default
1,3
1,2X.1
X.1
X.1
X.1
2.D2.C
2.B
3.A
3.D
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41ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
TokenRing
TokenRing
TokenRing
TokenRing
Totally Stubby AreaTotally Stubby Area
From area 1’s viewpoint
• Only a default network is injected into the areaRepresents external networks and all inter-area routes
• Default path to closest area border router
• Define all routers in the area as totally stubbyarea x stub no-summary command ASBR
External Networks
1.A
1.C
1.B
1.DTokenRing
TokenRing
3.C
3.B
2.A
Default 2&3
1,3
1,2X.1
X.1
X.1
X.1
2.D2.C
2.B
3.A
3.D
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42ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
TokenRing
TokenRing
TokenRing
TokenRing
Not-So-Stubby AreaNot-So-Stubby Area
• Capable of importing external routes in a limitedfashion
• Type-7 LSA’s carry external information within anNSSA
• NSSA Border routers translate selected type-7LSAs into type-5 external network LSAs ASBR
External Networks
1.A
1.C
1.B
1.DTokenRing
TokenRing
3.C
3.B
2.A
Default 2&3
1,3
1,2X.1
X.1, X.2
X.1, X.2X.1
2.D2.C
2.B
3.A
3.DExternalNetworks
X.2
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43ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
AddressingAddressing
Area 1network 131.108.0.0subnets 17-31range 255.255.240.0
Area 2network 131.108.0.0subnets 33-47range 255.255.240.0
Area 3network 131.108.0.0subnets 49-63range 255.255.240.0
Area 0network 192.117.49.0range 255.255.255.0
Assign contiguous ranges of subnets per area to facilitate summarisation
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44ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
SummarySummary
• Scalable OSPF Network Design
Area hierarchy
Stub areas
Contiguous addressing
Route summarisation
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45ISP/IXP Workshops © 1999, Cisco Systems, Inc.
OSPF Design InService Provider
Networks
OSPF Design InOSPF Design InService ProviderService Provider
NetworksNetworks
45ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
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46ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
BackboneBackboneRouterRouter
OSPF Areas and RulesOSPF Areas and RulesOSPF Areas and Rules
Area 1
Area 4
Area 0
Area 2 Area 3
InternalInternalRouterRouter
AreaAreaBorderBorderRouterRouter
AutonomousAutonomousSystem (AS)System (AS)
Border RouterBorder Router
Internet
• Backbone area (0)must be present
• All other areasmust haveconnectionto backbone
• Backbone mustbe contiguous
• Do not partitionarea (0)
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47ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
OSPF DesignOSPF DesignOSPF Design
• Attack addressing first - OSPF andAddressing go together.
Objective is to keep the Link State DataBase lean.
Create address hierarchy to matchtopology
Separate Blocks for infrastructure,customer interfaces, customers, etc.
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48ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
OSPF DesignOSPF DesignOSPF Design
• Examine physical topology
Is it meshed or hub-and-spoke?
• Try to use as Stubby an area as possible
It reduces overhead and LSA counts
• Push the creation of a backbone
Reduces mesh and promotes hierarchy
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49ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
OSPF DesignOSPF Design
• One SPF per area, flooding done per areaWatch out for overloading ABRs
• Different types of areas do differentflooding
Normal areas
Stub areas
Totally stubby (stub no-summary)
Not so stubby areas (NSSA)
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50ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
OSPF DesignOSPF Design
• Redundancy
Dual Links out of each area - usingmetrics (cost) for traffic enginering
Too much redundancy…
Dual links to backbone in stub areasmust be the same - other wise sub-optimal routing will result
Too Much Redundancy in the backbonearea without good summarization willeffect convergence in the area 0
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51ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
OSPF for ISPsOSPF for ISPsOSPF for ISPs
• OSPF features should consider.
OSPF logging neighbour changes
OSPF reference cost
OSPF Router ID Command
OSPF Process Clear/Restart
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52ISP/IXP Workshops © 1999, Cisco Systems, Inc.
OSPF BCPAdding Networks
OSPF BCPOSPF BCPAdding NetworksAdding Networks
52ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
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53ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
OSPF - Adding NetworksOSPF - Adding NetworksOSPF - Adding Networks
• BCP - Individual OSPFNetwork statement foreach infrastructure link.
Have separate IP addressblocks for infrastructureand customer links.
Use IP UnnumberedInterfaces or BGP to carry/30s to customers
OSPF should only carryinfrastructure routes in anISP’s network.
OC12c
OC12c
Customer Connections
OC48
ISP Backbone
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54ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
OSPF - Adding Networks(Method One)
OSPF - Adding NetworksOSPF - Adding Networks(Method One)(Method One)
• redistributed connect subnets
Works for all connected interfaces on therouter but sends networks as externaltype-2s - which are not summarized
router ospf 100
redistributed connected subnets
• Not recommended
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55ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
OSPF - Adding NetworksOSPF - Adding NetworksOSPF - Adding Networks
• Specific network statements
Every interface needs a OSPF networkstatement. Interface that should not bebroadcasting OSPF Hello packets needspassive-interface.
router ospf 100
network 192.168.1.4 0.0.0.3 area 51
network 192.168.1.6 0.0.0.3 area 51
passive interface Serial 1/0
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56ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
OSPF - Adding NetworksOSPF - Adding NetworksOSPF - Adding Networks
• Network statements - wildcard mask
Every interface covered by wildcard maskused in OSPF network statement.Interfaces that should not be broadcastingOSPF Hello packets need passive-interfaceor default passive-interface.
router ospf 100
network 192.168.1.0 0.0.0.255 area 51
default passive-interface default
no passive interface POS 4/0
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57ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
OSPF - Adding NetworksOSPF - Adding NetworksOSPF - Adding Networks
• Key Theme when selecting atechnique: Keep the Link StateDatabase Lean
Increases Stability
Reduces the amount of information inthe Link State Advertisements (LSAs)
Speeds Convergence Time
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58ISP/IXP Workshops © 1999, Cisco Systems, Inc.
OSPF - New and UsefulFeatures
OSPF - New and UsefulOSPF - New and UsefulFeaturesFeatures
58ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
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59ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
OSPF Logging NeighbourOSPF Logging NeighbourChangesChanges
• The router will generate a log messagewhenever an OSPF neighbour changes state
• Syntax:
[no] ospf log-adjacency-changes[no] ospf log-adjacency-changes
• Example of a typical log message:
%OSPF-5-ADJCHG: Process 1,%OSPF-5-ADJCHG: Process 1, Nbr Nbr223.127.255.223 on Ethernet0 from LOADING to223.127.255.223 on Ethernet0 from LOADING toFULL, Loading DoneFULL, Loading Done
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60ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Number of State ChangesNumber of State Changes
• The number of state transitions isavailable via SNMP (ospfNbrEvents)and the CLI:
show ip ospf neighbor [type number]show ip ospf neighbor [type number][neighbor-id] [detail][neighbor-id] [detail]
Detail—(Optional) Displays all neighboursgiven in detail (list all neighbours). Whenspecified, neighbour state transition countersare displayed per interface or neighbour ID
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61ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
State Changes (Continued)State Changes (Continued)
• To reset OSPF-related statistics, usethe clear ip ospf countersclear ip ospf counters EXECcommand. At this point neighborneighbor is theonly available option; it will resetneighbour state transition counters perinterface or neighbour id
clear ip ospf counters [neighbor [<typeclear ip ospf counters [neighbor [<typenumber>] [neighbor-id]]number>] [neighbor-id]]
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62ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
OSPF Cost: ReferenceOSPF Cost: ReferenceBandwidthBandwidth
• Bandwidth used in Metric calculation
Cost = 10^8/BW
Not useful for BW > 100 Mbps
• Syntax:ospf auto-cost reference-bandwidth <reference-ospf auto-cost reference-bandwidth <reference-bandwidth>bandwidth>
• Default reference bandwidth still 100Mbps for backward compatibility
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63ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
OSPF Router IDOSPF Router IDOSPF Router ID
• If the loopback interface exists and has anIP address, that is used as the router ID inrouting protocols - stability!
• If the loopback interface does not exist, orhas no IP address, the router ID is thehighest IP address configured - danger!
• New sub command to manually set theOSPF Router ID:
router-id <ip address>
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64ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
OSPF Clear/RestartOSPF Clear/RestartOSPF Clear/Restart
• clear ip ospf [pid] redistribution
This command can now clear redistribution based on OSPF routingprocess ID. If no pid is given, it assumes all OSPF processes.
• clear ip ospf [pid] counters
This command can now clear counters based on OSPF routingprocess ID. If no pid is given, it assumes all OSPF processes.
• clear ip ospf [pid] process
This command will restart the specified OSPF process. If no pid isgiven, it assumes all OSPF processes. It attempts to keep the oldrouter-id, except in cases, where a new router-id was configured, oran old user configured router-id was removed. Since this commandcan potentially cause a network churn, a user confirmation isrequired before performing any action.
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65ISP/IXP Workshops © 1999, Cisco Systems, Inc.
OSPF CommandSummary
OSPF CommandOSPF CommandSummarySummary
65ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
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66ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Redistributing Routes intoRedistributing Routes intoOSPFOSPF
ROUTER OSPF <pid#x>
REDISTRIBUTE {protocol} <as#y>
<metric>
<metric-type (1 or 2)
<tag>
<subnets>
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67ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Router Sub-commandsRouter Sub-commands
• NETWORK <n.n.n.n> <mask> AREA <area-id>
• AREA <area-id> STUB {no-summary}
• AREA <area-id> AUTHENTICATION
• AREA <area-id> DEFAULT_COST <cost>
• AREA <area-id> VIRTUAL-LINK <router-id>...
• AREA <area-id> RANGE <address mask>
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68ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com
Interface SubcommandsInterface Subcommands
• IP OSPF COST <cost>
• IP OSPF PRIORITY <8-bit-number>
• IP OSPF HELLO-INTERVAL <number-of-seconds>
• IP OSPF DEAD-INTERVAL <number-of-seconds>
• IP OSPF AUTHENTICATION-KEY <8-bytes-of-password>
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69