Are you ready to find prefixes that go bump in the night?Here is the sample Trouble Ticket we will attack , and the appropriate portion of the Cisco diagram .You will want to have so mescratch paper handy(just like in the actual exam).Diagramming can prove to be more important here then in any exam section.You should practice a diagram now based on the show output that follows.
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TroubleTicket1
VampireslocatedinVLAN666(behindAmityville)areunabletoaccessanyresourceslocatedbehindTransylvania.Correctthisissuewithoutstaticrouting,additionalroutingprotocols,orredistributionofanykind.
Thefirstorderofbusinessisto“expand”upontheirdiagramanddeterminewhatprotocolsareinuseandwhere.Aquickshowipprotocolsoneachofthedevicesinthetransitpathshoulddothetrick.
Transylvania#showipprotocols
RoutingProtocolis"eigrp100"
Outgoingupdatefilterlistforallinterfacesisnotset
Incomingupdatefilterlistforallinterfacesisnotset
Defaultnetworksflaggedinoutgoingupdates
Defaultnetworksacceptedfromincomingupdates
EIGRPmetricweightK1=1,K2=0,K3=1,K4=0,K5=0
EIGRPmaximumhopcount100
EIGRPmaximummetricvariance1
Redistributing:eigrp100
EIGRPNSF-awarerouteholdtimeris240s
Automaticnetworksummarizationisnotineffect
Maximumpath:4
RoutingforNetworks:
53.234.10.23/32
RoutingInformationSources:
GatewayDistanceLastUpdate
Distance:internal90external170
RoutingProtocolis"bgp65001"
Outgoingupdatefilterlistforallinterfacesisnotset
Incomingupdatefilterlistforallinterfacesisnotset
IGPsynchronizationisdisabled
Automaticroutesummarizationisdisabled
UnicastAggregateGeneration:
10.10.0.0/16summary-only
Neighbor(s):
AddressFiltInFiltOutDistInDistOutWeightRouteMap
53.234.10.44
Maximumpath:1
RoutingInformationSources:
GatewayDistanceLastUpdate
Distance:external20internal200local200
HalloweenTown#showipprotocols
RoutingProtocolis"eigrp100"
Outgoingupdatefilterlistforallinterfacesisnotset
Incomingupdatefilterlistforallinterfacesisnotset
Defaultnetworksflaggedinoutgoingupdates
Defaultnetworksacceptedfromincomingupdates
EIGRPmetricweightK1=1,K2=0,K3=1,K4=0,K5=0
EIGRPmaximumhopcount100
EIGRPmaximummetricvariance1
Redistributing:eigrp100
EIGRPNSF-awarerouteholdtimeris240s
Automaticnetworksummarizationisnotineffect
Maximumpath:4
RoutingforNetworks:
53.234.10.44/32
RoutingInformationSources:
GatewayDistanceLastUpdate
Distance:internal90external170
RoutingProtocolis"bgp65001"
Outgoingupdatefilterlistforallinterfacesisnotset
Incomingupdatefilterlistforallinterfacesisnotset
IGPsynchronizationisdisabled
Automaticroutesummarizationisdisabled
Neighbor(s):
AddressFiltInFiltOutDistInDistOutWeightRouteMap
23.10.24.190
53.234.10.23
Maximumpath:1
RoutingInformationSources:
GatewayDistanceLastUpdate
Distance:external20internal200local200
Salem#showipprotocols
RoutingProtocolis"ospf1"
Outgoingupdatefilterlistforallinterfacesisnotset
Incomingupdatefilterlistforallinterfacesisnotset
RouterID66.150.201.12
Numberofareasinthisrouteris1.1normal0stub0nssa
Maximumpath:4
RoutingforNetworks:
RoutingonInterfacesConfiguredExplicitly(Area0):
FastEthernet0/0
Referencebandwidthunitis100mbps
RoutingInformationSources:
GatewayDistanceLastUpdate
102.34.102.1211000:30:55
Distance:(defaultis110)
RoutingProtocolis"bgp65000"
Outgoingupdatefilterlistforallinterfacesisnotset
Incomingupdatefilterlistforallinterfacesisnotset
IGPsynchronizationisdisabled
Automaticroutesummarizationisdisabled
Neighbor(s):
AddressFiltInFiltOutDistInDistOutWeightRouteMap
23.10.24.200
Maximumpath:1
RoutingInformationSources:
GatewayDistanceLastUpdate
Distance:external20internal200local200
CrystalLake#showipprotocols
RoutingProtocolis"ospf1"
Outgoingupdatefilterlistforallinterfacesisnotset
Incomingupdatefilterlistforallinterfacesisnotset
RouterID102.34.102.1
Numberofareasinthisrouteris1.1normal0stub0nssa
Maximumpath:4
RoutingforNetworks:
RoutingonInterfacesConfiguredExplicitly(Area0):
FastEthernet0/1
FastEthernet0/0
Referencebandwidthunitis100mbps
RoutingInformationSources:
GatewayDistanceLastUpdate
Distance:(defaultis110)
RoutingProtocolis"bgp65000"
Outgoingupdatefilterlistforallinterfacesisnotset
Incomingupdatefilterlistforallinterfacesisnotset
IGPsynchronizationisdisabled
Automaticroutesummarizationisdisabled
Neighbor(s):
AddressFiltInFiltOutDistInDistOutWeightRouteMap
66.150.201.12
AddressFiltInFiltOutDistInDistOutWeightRouteMap
102.34.102.12
Maximumpath:1
RoutingInformationSources:
GatewayDistanceLastUpdate
Distance:external20internal200local200
Amityville#showipprotocols
RoutingProtocolis"ospf1"
Outgoingupdatefilterlistforallinterfacesisnotset
Incomingupdatefilterlistforallinterfacesisnotset
RouterID102.34.102.12
Numberofareasinthisrouteris1.1normal0stub0nssa
Maximumpath:4
RoutingforNetworks:
RoutingonInterfacesConfiguredExplicitly(Area0):
FastEthernet0/0
Referencebandwidthunitis100mbps
RoutingInformationSources:
GatewayDistanceLastUpdate
102.34.102.111000:33:23
Distance:(defaultis110)
RoutingProtocolis"bgp65000"
Outgoingupdatefilterlistforallinterfacesisnotset
Incomingupdatefilterlistforallinterfacesisnotset
IGPsynchronizationisdisabled
Automaticroutesummarizationisdisabled
Neighbor(s):
AddressFiltInFiltOutDistInDistOutWeightRouteMap
102.34.102.1
Maximumpath:1
RoutingInformationSources:
GatewayDistanceLastUpdate
Distance:external20internal200local200AsIparsetheresults,Icreateamoredetaileddiagramtoprovideabetterpictureofwhatisgoingon.Lookingatthediagram,Iimmediatelycontemplatesomedesignissuesthatcouldcomeintoplay.TheiBGPsplit-horizonrule,next-hopreachability,andsynchronizationallcouldcomeintoplayheregiventheprotocolconfiguration.
Idecidetostartasclosethedestinationaspossibleandexaminetherelevantconfigurations.
Transylvania#showrun|sectionbgp
routerbgp65001
nosynchronization
bgplog-neighbor-changes
network10.0.0.0
aggregate-address10.10.0.0255.255.0.0summary-only
neighbor53.234.10.44remote-as65001
noauto-summaryItappearstheintentistoadvertiseprefixes(theLoopbackinterfaces)beyondTransylvaniausingBGPprefixaggregation.Letmeensurethatconfigurationisdonecorrectly.
Sureenough,hereisourfirstBGPconfigurationissue.Weneedtoadvertiseacomponentprefixoftheaggregate.Thelittlegremlinthatattemptedthisconfigurationtriedtoaccomplishthiswiththenetworkstatement,buttheygotitwrong.Subnettingisbeingdonehereofthe10.x.x.xspace,soyouneedtoreconfigurethenetworkstatementasfollows:
Transylvania#showipintbrief
InterfaceIP-AddressOK?MethodStatusProtocol
FastEthernet0/053.234.10.23YESmanualupup
FastEthernet0/1unassignedYESunsetadministrativelydowndown
Loopback110.10.10.1YESmanualupup
Loopback210.10.11.1YESmanualupup
Loopback310.10.12.1YESmanualupup
Transylvania#configureterminal
Enterconfigurationcommands,oneperline.EndwithCNTL/Z.
Transylvania(config)#routerbgp65001
Transylvania(config-router)#network10.10.10.0mask255.255.255.0
Aftermakingthischange,IcheckSalemtoseeifitisreceivingtheaggregatefromTransylvaniaandwehavereachability:
Salem#showipbgp
BGPtableversionis2,localrouterIDis66.150.201.12
Statuscodes:ssuppressed,ddamped,hhistory,*valid,>best,i-internal,
rRIB-failure,SStale
Origincodes:i-IGP,e-EGP,?-incomplete
NetworkNextHopMetricLocPrfWeightPath
*>10.10.0.0/1623.10.24.200065001i
Salem#showiproutebgp
10.0.0.0/16issubnetted,1subnets
B10.10.0.0[20/0]via23.10.24.200,00:06:26
Salem#ping10.10.10.1
Typeescapesequencetoabort.
Sending5,100-byteICMPEchosto10.10.10.1,timeoutis2seconds:
!!!!!
Successrateis100percent(5/5),round-tripmin/avg/max=28/33/40msWeareonourwaytosolvingthisTroubleTicket…wehopeyouwillfollowthisblogandcontinuethis(andmore)troubleshootingscenarios!
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