troubleshooting ospf and eigrp routing...

Troubleshooting OSPF and EIGRP Routing Protocols

Hassaan Ahmed, Customer Support EngineerBRKRST-2619

• Troubleshooting Methodology• OSPF Overview• Troubleshooting OSPF• EIGRP Overview• Troubleshooting EIGRP

Agenda

Troubleshooting Methodology

© 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public

Troubleshooting Methodology

5

Form Neighbour Relationship

Build the Protocol Database

Populate the IP Routing Table

Run Routing Algorithm

OSPF Overview


OSPF Areas• Link State protocol

• Uses a 2 level hierarchical model

• Areas defined with 32 bit number

Defined in IP address format or single decimal value (i.e., Area 0.0.0.0, or Area 0)

• 0.0.0.0 (0) reserved for the backbone area

• Runs Shortest Path First (SPF) algorithm

Area 3

Area 0

Area 1

Area 2


OSPF LSAs – OSPFv2• Router and Network LSA’s within an

area (Type 1 and Type 2)

• Summary LSA Type 3 outside the area. Generated by ABR.

• Summary LSA Type 4 generated by ABR to describe route to ASBR

• Type 5 for redistributed routes generated by ASBR

• Partial SPF for summary and External LSA’s

Area 0

Area 1

Area 2

Area 3


OSPF LSAs – OSPFv3• Router and Network LSA’s within an area

(Type 1 and Type 2). Do not carry prefix information.

• Link LSA Type 8 have link local scope. Used to notify neighbourabout the attached addresses on that link.

• Intra-area Prefix LSA Type 9. Advertises router itself, attached stub networks and transit network segments.

• Inter-area prefix LSA Type 3 outside the area. Generated by ABR.

• Inter-area router LSA Type 4. Generated by ABR to describe route to ASBR.

• AS-External LSA Type 5 for redistributed routes generated by ASBR.

Area 0

Area 1Area 2

Area 3


OSPF Neighbour Adjacency Process

RID =10.2.2.2

Hello

RID =10.1.1.1

Hello

RID =10.1.1.1

HelloN =10.2.2.2

RID =10.2.2.2

N =10.1.1.1

Hello

10.2.2.2

R2

10.1.1.1

R1

• Init

• 2-Way

{{ 2-Way on R2

2-Way on R1

Init on R2

Init on R1


MTU = 1500 Flag = 0x7

Seq = 0x2499

DBD

MTU = 1500Flag = 0x3

Seq = 0x837

DBD

• EXSTART

• EXCHANGE

10.2.2.2

R2

10.1.1.1

R1



LS TypeLink State ID

Advertising Router

LS Request

# LSA’sLSA’sLSA ..

LS Update

• LOADING

• FULL

10.2.2.2

R2

10.1.1.1

R1


Troubleshooting OSPF/OSPFv3


Lifecycle View of the OSPF Routing Process

Form OSPF Neighbour Relationship

Build the OSPF LSADatabase


Run OSPF SPF Routing Algorithm


OSPF not enabled on the interface

R1#show ip/ipv6 ospf neighborR1#

R1#show ip/ipv6 ospf interface eth 0/0Ethernet0/0 is up, line protocol is up

OSPF not enabled on this interface

Adjacency Is Not Coming Up

In 12.0:

R1#show ip/ipv6 ospf interface eth0/0R1#

Check for wrong network statement / For OSPFv3, check interface configuration for missing “ipv6 ospf area” command


• Mismatched subnet mask (OSPFv2 only) / Hello - Dead Interval

R1#show ip/ipv6 ospf neighborR1#

R1#debug ip/ipv6 ospf helloOSPF adjacency events debugging is on

OSPF: Mismatched hello parameters from 10.0.0.2Dead R 40 C 40, Hello R 10 C 10 Mask R 255.255.255.192 C 255.255.255.0

10.1.1.1 10.2.2.2

R2R1Area 2 Area 2

10.0.0.2/2610.0.0.1/24



• Mismatched area ID

OSPF: Rcv pkt from 10.0.0.2, Et0/0, area 0.0.0.0 mismatch area 0.0.0.2 in the header

On R2:

%OSPF-4-ERRRCV: Received invalid packet: mismatch area ID, from backbone area must be virtual-link but not found from 10.0.0.1, Ethernet0/0

R1#debug ip/ipv6 ospf adjOSPF adjacency events debugging is on

10.1.1.1 10.2.2.2

R2R1Area 0 Area 2

10.0.0.210.0.0.1



• Mismatched transit/stub/NSSA option

OSPF-1 HELLO Et0/0: Rcv hello from 10.2.2.2 area 2 10.0.0.2OSPF-1 HELLO Et0/0: Hello from 10.0.0.2 with mismatched NSSA option bit

R1#show ip/ipv6 ospf neighbor

R1#debug ip/ipv6 ospf helloOSPF adjacency events debugging is on


10.1.1.1 10.2.2.2

R2R1Area 2 Area 2 NSSA

10.0.0.210.0.0.1


• Mismatched instance-ID

Either change R2 instance ID to 2 or change R1 instance ID back to 0

R1#show ipv6 ospf neighborR1# R1#sh ipv6 ospf int e0/0 | inc InstanceArea 1, Process ID 1, Instance ID 2, Router ID 10.1.1.1

R2#sh ipv6 ospf int e0/0 | inc InstanceArea 1, Process ID 1, Instance ID 0, Router ID 10.2.2.2

10.1.1.1 10.2.2.2

R2R1 Area 1 Area 1

Adjacency Is Not Coming Up – OSPFv3 Only


• No IPv6 address on the interface

OSPFv3 runs over link local address. Link local or unicast global address is required to be configured on interface.

R1#show ipv6 ospf neighborR2#

R1#sh ipv6 int e0/0

Adjacency Is Not Coming Up – OSPFv3 Only

10.1.1.1 10.2.2.2

R2R1 Area 1 Area 1


• One side is blocking the hello packet with access-list

• One side is translating (NAT) OSPF hello

• One side multicast capabilities is broken (Layer 2)

• OSPF authentication mismatch (only IPv4)

Stuck in INIT


• Normal in Broadcast Network

• All OSPF Routers have 0 priority

Stuck in 2-WAY


• MTU mismatch— Stuck in EXCHANGE/EXSTART

• Neighbour RID is same as ours— Stuck in EXSTART

• Unicast is broken—Stuck in EXCHANGE/EXSTARTa. Wrong VC/DLCI mapping b. MTU problemc. Access-list blocking unicast

MTU = 1500 Flag = 0x7

Seq = 0x2499

DBD

MTU = 1500Flag = 0x3

Seq = 0x837

DBD

10.2.2.2

R2

10.1.1.1

R1

Adjacency stuck in Exchange/Exstart

© 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public 23

Router LSA

R2R1 R5R4

R3

10.1.123.0/242001:1:123::/64

10.1.24.0/242001:1:24::/64

10.1.45.0/242001:45::/64

Area 1Area 0 Area 2

10.1.5.0/24 / 2001:1:5::/64

10.20.1.0/242001:20:1::/6410.10.10.10/32

2001:10:10::10/128

Router IDsR1: 10.1.1.1R2: 10.2.2.2R3: 10.3.3.3R4: 10.4.4.4R5: 10.5.5.5

R1#sh ip ospf database router adv-router 10.2.2.2

LS Type: Router LinksLink State ID: 10.1.1.1Advertising Router: 10.1.1.1LS Seq Number: 80000003Checksum: 0x3C1Length: 48Number of Links: 2

Link connected to: a Stub Network(Link ID) Network/subnet number: 10.10.10.10(Link Data) Network Mask: 255.255.255.255Number of MTID metrics: 0TOS 0 Metrics: 1

Link connected to: a Transit Network(Link ID) Designated Router address: 10.1.123.2 (Link Data) Router Interface address: 10.1.123.1Number of MTID metrics: 0TOS 0 Metrics: 10

R1#sh ipv6 ospf database router adv-router 10.2.2.2

LS age: 1342Options: (V6-Bit, E-Bit, R-bit, DC-Bit)LS Type: Router LinksLink State ID: 0Advertising Router: 10.1.1.1LS Seq Number: 80000002Checksum: 0x8D46Length: 40Number of Links: 1

Link connected to: a Transit NetworkLink Metric: 10Local Interface ID: 2Neighbor (DR) Interface ID: 2Neighbor (DR) Router ID: 10.2.2.2

IPv4 IPv6


Network LSA

R2R1 R5R4

R3

10.1.123.0/242001:1:123::/64

10.1.24.0/242001:1:24::/64

10.1.45.0/242001:45::/64

Area 1Area 0 Area 2

10.1.5.0/24 / 2001:1:5::/64

10.20.1.0/242001:20:1::/6410.10.10.10/32

2001:10:10::10/128

Router IDsR1: 10.1.1.1R2: 10.2.2.2R3: 10.3.3.3R4: 10.4.4.4R5: 10.5.5.5

R1#sh ip ospf database network adv-router 10.2.2.2

OSPF Router with ID (10.1.1.1) (Process ID 1)

Net Link States (Area 1)

Routing Bit Set on this LSA in topology Base with MTID 0LS age: 1548Options: (No TOS-capability, DC)LS Type: Network LinksLink State ID: 10.1.123.2 (address of Designated Router)Advertising Router: 10.2.2.2LS Seq Number: 80000002Checksum: 0x72F9Length: 36Network Mask: /24

Attached Router: 10.2.2.2Attached Router: 10.1.1.1Attached Router: 10.3.3.3

R1#sh ipv6 ospf database network adv-router 10.2.2.2

OSPFv3 Router with ID (10.1.1.1) (Process ID 1)


LS age: 1656Options: (V6-Bit, E-Bit, R-bit, DC-Bit)LS Type: Network LinksLink State ID: 2 (Interface ID of Designated Router)Advertising Router: 10.2.2.2LS Seq Number: 80000002Checksum: 0xA021Length: 36

Attached Router: 10.2.2.2Attached Router: 10.1.1.1Attached Router: 10.3.3.3

IPv4 IPv6


Summary LSA / Inter-area Prefix LSA

R2R1 R5R4

R3

10.1.123.0/242001:1:123::/64

10.1.24.0/242001:1:24::/64

10.1.45.0/242001:45::/64

Area 1Area 0 Area 2

10.1.5.0/24 / 2001:1:5::/64

10.20.1.0/242001:20:1::/6410.10.10.10/32

2001:10:10::10/128

Router IDsR1: 10.1.1.1R2: 10.2.2.2R3: 10.3.3.3R4: 10.4.4.4R5: 10.5.5.5

R1#sh ip ospf database summary 10.1.5.0


Summary Net Link States (Area 1)

Routing Bit Set on this LSA in topology Base with MTID 0LS age: 1445Options: (No TOS-capability, DC, Upward)LS Type: Summary Links(Network)Link State ID: 10.1.5.0 (summary Network Number)Advertising Router: 10.2.2.2LS Seq Number: 80000001Checksum: 0x8A3ELength: 28Network Mask: /24

MTID: 0 Metric: 84

R1#show ipv6 ospf database inter-area prefix 2001:1:5::/64


Routing Bit Set on this LSALS age: 1655LS Type: Inter Area Prefix LinksLink State ID: 3Advertising Router: 10.2.2.2LS Seq Number: 80000001Checksum: 0x9CCBLength: 36Metric: 84Prefix Address: 2001:1:5::Prefix Length: 64, Options: None

IPv4 IPv6


Summary ASBR LSA / Inter-area Router LSA

R2R1 R5R4

R3

10.1.123.0/242001:1:123::/64

10.1.24.0/242001:1:24::/64

10.1.45.0/242001:45::/64

Area 1Area 0 Area 2

10.1.5.0/24 / 2001:1:5::/64

10.20.1.0/242001:20:1::/6410.10.10.10/32

2001:10:10::10/128

Router IDsR1: 10.1.1.1R2: 10.2.2.2R3: 10.3.3.3R4: 10.4.4.4R5: 10.5.5.5

R1#sh ip ospf database asbr-summary adv-router 10.2.2.2


Summary ASB Link States (Area 1)

Routing Bit Set on this LSA in topology Base with MTID 0LS age: 316Options: (No TOS-capability, DC, Upward)LS Type: Summary Links(AS Boundary Router)Link State ID: 10.5.5.5 (AS Boundary Router address)Advertising Router: 10.2.2.2LS Seq Number: 80000002Checksum: 0xB314Length: 28Network Mask: /0

MTID: 0 Metric: 74

R1#sh ipv6 ospf database inter-area router adv-router 10.2.2.2


Inter Area Router Link States (Area 1)

Routing Bit Set on this LSALS age: 355Options: (V6-Bit, E-Bit, R-bit, DC-Bit)LS Type: Inter Area Router LinksLink State ID: 168101125Advertising Router: 10.2.2.2LS Seq Number: 80000002Checksum: 0x3F3ALength: 32Metric: 74Destination Router ID: 10.5.5.5

IPv4 IPv6


AS External LSA

R2R1 R5R4

R3

10.1.123.0/242001:1:123::/64

10.1.24.0/242001:1:24::/64

10.1.45.0/242001:45::/64

Area 1Area 0 Area 2

10.1.5.0/24 / 2001:1:5::/64

10.20.1.0/242001:20:1::/6410.10.10.10/32

2001:10:10::10/128

Router IDsR1: 10.1.1.1R2: 10.2.2.2R3: 10.3.3.3R4: 10.4.4.4R5: 10.5.5.5

R1#show ip ospf database external 10.20.1.0


Routing Bit Set on this LSA in topology Base with MTID 0LS age: 586Options: (No TOS-capability, DC, Upward)LS Type: AS External LinkLink State ID: 10.20.1.0 (External Network Number )Advertising Router: 10.5.5.5LS Seq Number: 80000002Checksum: 0xA3C3Length: 36Network Mask: /24

Metric Type: 2 (Larger than any link state path)MTID: 0Metric: 20Forward Address: 0.0.0.0External Route Tag: 0

R1#show ipv6 ospf database external 2001:20:1::/64


Type-5 AS External Link States

Routing Bit Set on this LSALS age: 761LS Type: AS External LinkLink State ID: 0Advertising Router: 10.5.5.5LS Seq Number: 80000002Checksum: 0x79E6Length: 36Prefix Address: 2001:20:1::Prefix Length: 64, Options: NoneMetric Type: 2 (Larger than any link state path)Metric: 20

IPv4 IPv6


OSPFv3 Only - Link States – Type 8

R2R1 R5R4

R3

10.1.123.0/242001:1:123::/64

10.1.24.0/242001:1:24::/64

10.1.45.0/242001:45::/64

Area 1Area 0 Area 2

10.1.5.0/24 / 2001:1:5::/64

10.20.1.0/242001:20:1::/6410.10.10.10/32

2001:10:10::10/128

Router IDsR1: 10.1.1.1R2: 10.2.2.2R3: 10.3.3.3R4: 10.4.4.4R5: 10.5.5.5

R1#show ipv6 ospf database


<output omitted>

Link (Type-8) Link States (Area 1)

ADV Router Age Seq# Link ID Interface10.1.1.1 1559 0x80000003 2 Et0/010.2.2.2 1438 0x80000003 2 Et0/010.3.3.3 1302 0x80000003 2 Et0/0

R1#show ipv6 ospf database link adv-router 10.2.2.2


Link (Type-8) Link States (Area 1)

LS age: 1566Options: (V6-Bit, E-Bit, R-bit, DC-Bit)LS Type: Link-LSA (Interface: Ethernet0/0)Link State ID: 2 (Interface ID)Advertising Router: 10.2.2.2LS Seq Number: 80000003Checksum: 0x7B41Length: 56Router Priority: 1Link Local Address: FE80::A8BB:CCFF:FE00:200Number of Prefixes: 1Prefix Address: 2001:1:123::Prefix Length: 64, Options: None


OSPFv3 Only - Intra Area Prefix LSA – Type 9

R2R1 R5R4

R3

10.1.123.0/242001:1:123::/64

10.1.24.0/242001:1:24::/64

10.1.45.0/242001:45::/64

Area 1Area 0 Area 2

10.1.5.0/24 / 2001:1:5::/64

10.20.1.0/242001:20:1::/6410.10.10.10/32

2001:10:10::10/128

Router IDsR1: 10.1.1.1R2: 10.2.2.2R3: 10.3.3.3R4: 10.4.4.4R5: 10.5.5.5

R1#show ipv6 ospf database


<output omitted>

Intra Area Prefix Link States (Area 1)

ADV Router Age Seq# Link ID Ref-lstype Ref-LSID10.1.1.1 1767 0x80000004 0 0x2001 010.2.2.2 1647 0x80000002 2048 0x2002 2

R1#show ipv6 ospf database prefix adv-router 10.1.1.1


Intra Area Prefix Link States (Area 1)Routing Bit Set on this LSALS age: 1991LS Type: Intra-Area-Prefix-LSALink State ID: 0Advertising Router: 10.1.1.1LS Seq Number: 80000004Checksum: 0x719CLength: 52Referenced LSA Type: 2001Referenced Link State ID: 0Referenced Advertising Router: 10.1.1.1Number of Prefixes: 1Prefix Address: 2001:10:10::10Prefix Length: 128, Options: LA, Metric: 0


SPF Running Constantly

Reasons

• LSA Flaps due to:

•Duplicate RID/IP address•Constant link flapping in an area


R1#show ip/ipv6 ospf statistic Area 0: SPF algorithm executed 42 timesArea 1: SPF algorithm executed 38 timesSPF calculation time

Delta T Intra D-Intra Summ D-Summ Ext D-Ext Total Reason00:22:00 0 0 0 0 0 0 0 R, N, SN, 00:21:44 0 0 4 0 0 0 4 R, SN, X00:21:34 0 0 4 0 0 0 4 R, SN, X00:21:24 0 0 0 4 0 0 4 R, SN, X00:21:14 0 0 0 0 0 0 0 R, 00:21:04 0 0 0 0 0 0 0 R, N, SN, 00:20:54 0 0 0 0 0 0 0 X00:20:44 0 0 4 0 0 0 4 R, SN, X00:20:34 0 0 0 0 0 0 0 X00:00:17 4 0 0 0 0 0 4 R, N, SN, SA, X. . .R=Router LSA; N=NetworkLSA; SN=Summary Network LSA; SA=Summary ASBR LSA;X=External LSA



R1#show ip/ipv6 ospf statistic detailOSPF process ID 100------------------------------------------Area 0: SPF algorithm executed 1 times

SPF 1 executed 1w0d ago, SPF type FullSPF calculation time (in msec):SPT Intra D-Intr Summ D-Summ Ext7 D-Ext7 Total0 0 0 0 0 0 0 0LSIDs processed R:1 N:0 Stub:1 SN:0 SA:0 X7:0Change record R,LSIDs changed 1Last 10 LSIDs:10.2.2.2(R)Summary OSPF SPF statisticSPF calculation time

Delta T Intra D-Intra Summ D-Summ Ext D-Ext Total Reason1w0d 0 0 0 0 0 0 0 R,



R2#debug ip/ipv6 ospf monitorOSPF: Schedule SPF in area 1

Change in LS ID 10.1.1.1, LSA type R,OSPF: schedule SPF: spf_time 0ms wait_interval 861421816s OSPF: Begin SPF at 0x33585480ms, process time 752ms spf_time 0ms, wait_interval 861421816sOSPF: End SPF at 0x33585488ms, Total elapsed time 8ms

Intra: 4ms, Inter: 0ms, External: 0ms


R2#debug ip/ipv6 ospf spfOSPFv3-1-IPv6 SPF : Changed LSA 10.1.1.1/0, type 2009, area 0OSPFv3-1-IPv6 SPF : Detect MAXAGE in LSA 10.1.1.1/0, type 2009OSPFv3-1-IPv6 SPF : reset throttling to 5000ms next wait-interval 10000msOSPFv3-1-IPv6 INTRA: Running SPF for area 0, cause POSPFv3-1-IPv6 INTRA: Intra-Area SPF (Prefix), Area 0OSPFv3-1-IPv6 INTRA: Process Prefix LSAs


SPF Running ConstantlyR1#show ip/ipv6 ospf database


Router Link States (Area 1)

Link ID ADV Router Age Seq# Checksum Link count10.1.1.1 10.1.1.1 2 0x80000006 0x00FCC4 210.2.2.2 10.2.2.2 1742 0x80000008 0x00CF21 110.3.3.3 10.3.3.3 1873 0x80000004 0x00AC42 1


Link ID ADV Router Age Seq# Checksum10.1.123.2 10.2.2.2 5 0x80000004 0x006EFB


OSPF Traffic Statistics

35

Summary traffic statistics for process ID 1:

OSPF packets received/sent

Type Packets BytesRX Invalid 0 0RX Hello 8 384RX DB des 8 496RX LS req 2 72RX LS upd 8 740RX LS ack 4 236RX Total 30 1928

TX Failed 0 0TX Hello 10 792TX DB des 6 624TX LS req 2 112TX LS upd 8 708TX LS ack 5 460TX Total 31 2696

OSPF header errorsLength 0, Checksum 0, Version 0, Bad Source 0,No Virtual Link 0, Area Mismatch 0, No Sham Link 0,Self Originated 0, Duplicate ID 0, Hello 0,MTU Mismatch 0, Nbr Ignored 0, LLS 0,Authentication 0, TTL Check Fail 0,

OSPF LSA errorsType 0, Length 0, Data 0, Checksum 0,

show ip/ipv6 ospf <process_id> traffic


OSPF Routing Table

36

R1#sh ip ospf nei

Neighbor ID Pri State Dead Time Address Interface

10.2.2.2 0 FULL/ - 00:00:30 10.0.0.2 Serial0/0

R2#sh ip ospf nei

Neighbor ID Pri State Dead Time Address Interface

10.1.1.1 1 FULL/BDR 00:00:30 10.0.0.1 Serial0/0

R1#sh ip route ospf

R1#

Prefix in Database but not in the Routing Table

R210.0.0.1/30 10.0.0.2/30

Area 0

R1

10.1.1.1 10.2.2.2


OSPF Routing Table

37

R1#sh ip ospf data router 10.2.2.2

OSPF Router with ID (10.1.1.1) (Process ID 1)Adv Router is not-reachableLS age: 1254

Options: (No TOS-capability, DC)LS Type: Router Links

Link State ID: 10.2.2.2Advertising Router: 10.2.2.2

Link connected to: a Transit Network

(Link ID) Designated Router address: 10.0.0.2(Link Data) Router Interface address: 10.0.0.2Number of TOS metrics: 0

TOS 0 Metrics: 10

R2#sh ip ospf data router 10.1.1.1

OSPF Router with ID (10.2.2.2) (Process ID 1)Adv Router is not-reachableLS age: 1670

Options: (No TOS-capability, DC)LS Type: Router Links

Link State ID: 10.1.1.1Advertising Router: 10.1.1.1

Link connected to: a Stub Network

(Link ID) Network/subnet number: 10.0.0.0(Link Data) Network Mask: 255.255.255.252Number of TOS metrics: 0

TOS 0 Metrics: 10

R210.0.0.1/30 10.0.0.2/30

Area 0

R1

10.1.1.1 10.2.2.2

EIGRP Overview


EIGRP Basics• Advanced distance vector, TLV based

protocol

• Uses DUAL algorithm

• Runs directly on top of IP/IPv6 protocol 88

• Uses multicast capabilities(Neighbour relationship &Updates)

• Supports unequal cost path load balancing

• Metric is based on the bandwidth and delay

EIGRP AS 1


• Hello process used for neighbour discovery and maintenanceHello TypesK-valueAS numberIP subnet (only IPv4)

• Multicast hellos (by default)224.0.0.10 / FF02::A

• IPv6 uses Link Local address to form neighbourship• Hello Interval

60 seconds for low-speed NBMA5 seconds for all other interfaces

EIGRP Neighbour Process

Hello

A

B

should match

40


EIGRP Reliable Communication

41

Reliable Transport Protocol (RTP)• Purpose of RTP

– To transmit and receive EIGRP packets

• Characteristics of RTP– Reliable & unreliable delivery:

§ Reliable delivery requires acknowledgment from destination§ Unreliable delivery does not require an acknowledgement from destination

– Packets can be § Unicast§ Multicast


• Feasible Distance (FD): minimum distance (metric) to a destination network.

• Reported distance (RD): distance (metric) towards a destination advertised by upstream neighbour.

• A neighbour meets the feasibility condition (FC) if the RD is smaller than the FD of this router.

EIGRP DUAL Routing Algorithm Concepts


EIGRP DUAL Routing Algorithm

43

• Finite-State-MachineTrack all routes

Select a SuccessorRemember Feasible Successors

If Successor lostUse Feasible Successor

If no Feasible Successor existsQuery Neighbours and Recompute new Successor

Troubleshooting EIGRP


Lifecycle View of the EIGRP Routing Process

45

Form EIGRP Neighbour Relationship

Build the EIGRPTopology Database


Run EIGRP Dual Routing Algorithm


R1#show ip/ipv6 eigrp neighborsIP-EIGRP neighbors for process 1H Address Interface Hold Uptime SRTT RTO Q Seq

(sec) (ms) Cnt Num2 10.0.0.2 Et0 12 6d16h 20 200 0 2331 10.8.0.5 Et1 13 2w2d 87 522 0 4520 10.9.0.7 Et1 10 2w2d 85 510 0 3

Seconds before declaring neighbour downHow long since the last time neighbour was discovered

How long we’ll wait before retransmitting if no acknowledgement* Normal to have 5000 during the startup

Number of EIGRP packets unacknowledged by the neighbour

How long it takes for neighbour to respond to reliable packets

EIGRP Neighbour Process

46

EIGRP Neighbours


EIGRP Neighbour Problems

47

• The hold time expires when an EIGRP packet is not received during hold time

• Ping the multicast Address (224.0.0.10 / FF02::A) from the Other Router

• Other checks:• Access-lists • Debug EIGRP packet hello• Ping neighbour with small & large packets• Interface errors• Sniffer Captures – external or internal• Configure neighbour statements (IPv4 only)

Neighbour 10.1.1.1 (Ethernet0) is down: holding time expired

A

B

HelloPing 224.0.0.10


• Manual configuration changes can also reset EIGRP neighbours:• Summary changes (manual and auto)• Route filter changes

• Graceful restart to resynchronise neighbour relationshipsclear ip/ipv6 eigrp neighbor <address> soft

EIGRP Neighbour Problems


Neighbor 10.0.0.2 (Ethernet0) is down: peer restartedNeighbor 10.0.0.2 (Ethernet0) is down: holding time expiredNeighbor 10.0.0.2 (Ethernet0) is down: retry limit exceededNeighbor 10.0.0.2 (Ethernet0) is down: route filter changed (old)Neighbor 10.0.0.2 (Ethernet0) is down: K-value mismatchNeighbor 10.0.0.2 (Ethernet0) is down: manually clearedNeighbor 10.0.0.2 (Ethernet0) is down: Interface Goodbye received

Neighbor 10.0.0.2 (Ethernet0) is resync: route configuration changedNeighbor 10.0.0.2 (Ethernet0) is resync: manually clearedNeighbor 10.0.0.2 (Ethernet0) is resync: peer graceful-restart

There are others, but not seen very often…

Example logs

EIGRP Different Log Messageseigrp log-neighbor-changes must be enabled under EIGRP process


EIGRP Topology Exchange• Reliable packets: re-sent after Retransmit Time Out

(Typically RTO = 6 X SRTT) • Minimum 200 ms and maximum 5000 ms

• After 16 retransmissions: re-initialise the neighbourR1#show ip eigrp neighborsIP-EIGRP neighbors for process 1H Address Interface Hold Uptime SRTT RTO Q Seq

(sec) (ms) Cnt Num

1 10.0.0.1 Et0/0 14 00:00:15 0 5000 4 0

Neighbour 10.0.0.1 (Ethernet0) is down: retry limit exceeded

R1

R2Packet

Ack

50

R1#sh ipv6 eigrp neighbors

EIGRP-IPv6 Neighbors for AS(1)H Address Interface Hold Uptime SRTT RTO Q Seq

(sec) (ms) Cnt Num1 Link-local address: Et0/0 12 00:00:16 1 100 3 7

FE80::A8BB:CCFF:FE00:300


EIGRP Topology Exchange• Ping the neighbour’s unicast address

- Vary the packet size- Try large numbers of packets

• This Ping Can Be Issued from Either Neighbour

• Common causes- Mismatched MTU- Unidirectional link- Dirty link- Bad Hardware

R2# pingProtocol[ip]: Target IP address: 10.0.0.1Repeat count [5]: 100Datagram Size: 1500Timeout in seconds[2]:Extended commands[n]: y

R1

R2

51


EIGRP Topology ExchangeR1#show ip eigrp eventsEvent information for AS 1:...10 13:20:43.289 Rcv update met/succmet: 409600 128256 11 13:20:43.289 Rcv update dest/nh: 10.2.2.0/24 10.0.0.2

R1

R2

Lo0: 10.1.1.1

Lo0: 10.2.2.2

10.0.0.0/24

Update

.1

.2

52

R1#show ipv6 eigrp eventsEvent information for AS 1:...13 15:37:13.791 Rcv update met/succmet: metric(2221056)

metric(2195456)14 15:37:13.791 Rcv update dest/nh: 2001:1:45::/64

FE80::A8BB:CCFF:FE00:200


EIGRP Event Log• Always running

• Separate event log for each Autonomous System

• Default 500 lines (configurable):

eigrp event-log-size ## (where ## are number of lines)

size 0 will disable log

• Most recent events at top.

• Clearing the event log:

clear ip eigrp event

53


EIGRP Topology Exchange

R1#debug ip/ipv6 eigrpIP-EIGRP Route Events debugging is on

R2#debug ip/ipv6 eigrp 10 10.2.2.0 255.255.255.0IP-EIGRP AS Target Events debugging is on

IP-EIGRP(Default-IP-Routing-Table:10): Processing incoming UPDATE packetIP-EIGRP(Default-IP-Routing-Table:10): Int 10.2.2.0/24 M 409600 – 256000 153600 SM128256 - 256 128000

R1

R2

Lo0: 10.1.1.1

Lo0: 10.2.2.2

10.0.0.0/24

Update

.1

.2

54


DUAL FD, RD, FS and Successor

55

A-B-E = 20+30 = 50A-C-E = 20+40 = 60A-D-E = 20+70 = 90

FD = 50

RD=4020 Se1/1

10.2

00.1

.0

RD=2020

A

B

C

D

E

RtrA#show ip/ipv6 eigrp topologyIP-EIGRP Topology Table for AS(1)/ID(10.1.1.1)..snip…..P 10.200.1.0/24, 1 successors, FD is 50

via 10.1.1.2 (50 / 30), Serial1/0via 10.1.2.2 (60 / 40), Serial1/1

ReportedDistance

ComputedDistance

Successor (A-B-E)Feasible Successor (A-C-E)

Feasible Distance


Show IP EIGRP Topology All-LinksShow ip eigrp topology all-links displays a list of All neighbours

RtrA#show ip/ipv6 eigrp topology all-linksIP-EIGRP Topology Table for AS(1)/ID(10.1.6.1)…..snip…..P 10.200.1.0/24, 1 successors, FD is 21026560

via 10.1.1.2 (21026560/20514560), Serial1/0via 10.1.2.2 (46740736/20514560), Serial1/1via 10.1.3.2 (46740736/46228736), Serial1/2

.2.1 .2

10.2

00.1

.0

56k 128k.1

A

B

C

D

E

Feasible SuccessorPossible Successor

Successor

Reported Distance

56


Show IP EIGRP Topology Summary

57

R1#sh ip/ipv6 eigrp topology sumIP-EIGRP Topology Table for AS(200)/ID(40.80.0.17)Head serial 1, next serial 1526589 routes, 0 pending replies, 0 dummiesIP-EIGRP(0) enabled on 12 interfaces, neighbors present on 4 interfacesQuiescent interfaces: Po3 Po6 Po2 Gi8/5

Total number of routes in the local topology table

Number of queries this router is waiting on replies forInternal data structures

Interfaces with no outstanding packets to be sent or acknowledged



58

• Normal state of a route is passive

• Going active is the normal during convergence• Successor is lost and no feasible successors• It means sending Queries to neighbours • SIA timer is 180 seconds



59

%DUAL-3-SIA: Route 10.64.5.0 255.255.255.192stuck-in-active state in IP-EIGRP 1. Cleaning up

• Two (probably) unrelated causes of the problem stuck and activeNeed to troubleshoot both parts

Cause of active often easier to findCause of stuck more important to find


Troubleshoot Stuck in Active

60

Show ip/ipv6 eigrp topology active (useful only during problem)R1#show ip eigrp topology activeIP-EIGRP Topology Table for AS(1)/ID(10.1.1.1)A 10.200.1.0/24, 1 successors, FD is Inaccessible

1 replies, active 00:01:17, query-origin: Local originvia Connected (Infinity/Infinity), Ethernet1/0

Remaining replies:via 10.0.0.2, r, Ethernet0/0

R1 is waiting on reply from 10.0.0.2

R1 R2 R3 R4 R510.0.0.0/24 10.10.0.0/24 10.20.0.0/24 10.30.0.0/24

10.200.1.0/24

1. Primary path goes down / No Feasible Successor

2. Query sent to R2 3. Query sent to R3 4. Query sent to R4.Drops in between

5. SIA-Query sent to R2after 1.5 mins

6. SIA-Reply from R2 R3 resets neighbourship with R4 after 3 mins


EIGRP Likely Causes for Stuck-in-Active

61

• Bad or congested links

• Query range is too long - Reduce Scope (stub routers) or Summarise

• Excessive redundancy

• Overloaded router (high CPU)

• Router memory shortage


Problem with External Routes

62

• EIGRP not installing external routes

• The first thing to check is:- default metric configured- metric tied to the redistribution statement

• default-metric• redistribute .... <metric>

A

B

C

10.1.1.0/24via RIP

router eigrp 100redistribute rip....

What metric should I use?

B#show ip route 10.1.1.0B#

C#show ip route 10.1.1.0C#


A

B

C

10.1.1.0/24via RIP

router eigrp 100redistribute rip metric 1000 1 255 1 1500....

B#show ip route 10.1.1.0....10.1.1.0/24 via [A]

C#show ip route 10.1.1.0C#

• We’ve resolved the metric issue, and B picked the route up, but C didn’t—why?

Problem with External Routes


192.168.1.1

• We’ve resolved the metric issue, and B picked the route up, but C didn’t—why?

• B’s topology table show originating router ID field in the external route is set to 192.168.1.1

• But, that’s Router C’s loopback address! B#show ip eigrp topology 10.1.1.0

10.10.1.0/24....External data:

Originating router is 192.168.1.1

A

B

C

10.1.1.0/24via RIPProblem with External Routes

1 02:30:18.591 Ignored route, metric: 192.168.1.0 2297856 2 02:30:18.591 Ignored route, neighbor info: 10.1.1.0/24 Serial0/3 3 02:30:18.591 Ignored route, dup router: 192.168.1.1

Problem indicated in event log:


IPv6 Unique Issues• IPv6 Router-ID: Uses the same router-id selection process as IPv4. If IPv4

address is not available manually set the router-ID.

• EIGRP does not use a network statement to specify its IPv6 interfaces

Two different methods exist:• Classic mode uses the “ipv6 eigrp <AS>” command on each interface• Named mode defaults to having all interfaces enabled

• Need to “shutdown” under af-interface <interface>

• Router process was defined to be shutdown by default in earlier versions.


Classic and Named ModeClassic Mode

R2#conf tEnter configuration commands, one per line. End with CNTL/Z.R2(config)#ipv6 router eigrp 1R2(config-rtr)#interface Serial4/0R2(config-if)#ipv6 eigrp 1

R2#sh run interface Serial4/0Interface Serial4/0ipv6 address 1:2::2/64ipv6 eigrp 1end

R2#sh run | section ipv6 routeripv6 router eigrp 1

R2#sh ipv6 eigrp topologyP 1:2::/64, 1 successors, FD is 2169856

via Connected, Serial4/0

Named mode

R1# conf tEnter configuration commands, one per line. End with CNTL/Z.R1(config)#router eigrp fooR1(config-router)#address-family ipv6 unicast auto 1

R1#sh run | section router eigrprouter eigrp foo!address-family ipv6 unicast autonomous-system 1! af-interface Serial4/0exit-af-interface!topology baseexit-af-topologyexit-address-family

R1#sh eigrp address-family ipv6 topologyP 1:1::/64, 1 successors, FD is 1735175958

via Connected, Serial4/0


Complete Your Online Session Evaluation

68BRKRST-2619

Learn online with Cisco Live! Visit us online after the conference for full access to session videos and presentations. www.CiscoLiveAPAC.com

Give us your feedback and receive a Cisco Live 2017 Cap by completing the overall event evaluation and 5 session evaluations.

All evaluations can be completed via the Cisco Live Mobile App.

Caps can be collected Friday 10 March at Registration.

Thank you

troubleshooting ospf and eigrp routing...

Documents