Bob Horne

1

• Bob Horne
• Network Consultant/CCIE 2884
• Compaq Computer Corporation
• NACSC/Network Services Unit

2
OSPF Troubleshooting

• OSPF Quick Review
• Troubleshooting Basics
• OSPF Problem Analysis

3
OSPF Quick Review

• Variable Length Prefix Routing
• Nothing new since A, B, C
• VLSM
• Longest Match
• Summarization

4
OSPF Review

• Distance Vector
• Convergence (Count to Infinity)
• Max Hops Limited
• Update Traffic
• Link state
• Memory/CPU Utilization
• Flooding
• LAN Designated Router (n(n-1)/2)

5
OSPF Review

• Local Multicast Hello
• 224.0.0.5
• 224.0.0.6
• Router ID
• Network Types
• PtP, MultiAccess, NBMA
• Virtual Links
• Stub Areas

6
OSPF Review

• Hierarchical by Design
• Backbone Area 0
• Route Selection
• Router Classification
• Backbone interface to area 0
• Internal all interfaces same area
• Area Border Router (ABR)
• Autonomous System Border (ASBR)

7
OSPF PACKET TYPES

• Hello
• Database Descriptor
• Link state Request
• Link State Advertisement
• Link State Acknowledgement

8
LINK STATE TYPES

• 1 Router Link Advertisements
• Router's link to the area
• Flooded within the area
• 2 Network Link Advertisements
• Generated by Designated Routers
• Flooded in the area that contains the network
• 3 Summary Link Advertisements
• Routes to networks
• Also used for aggregating routes
• 4 Summary Link Advertisements
• Describes routes to ASBR.
• 5 AS External Link Advertisements
• Originated by ASBR.
• Routes to destinations external to the AS
• Flooded all over except stub areas
• 7 NSSA

9
OSPF NEIGHBORS

• Init
• Hello detected
• Two-way
• Own RID seen
• DR/BDR elected
• ExStart
• Sequence number
• Primary/Secondary
• Primary will POLL
• Exchange
• LSAs flooded
• Loading
• Retransmissions
• Full
• Adjacency established

10
Troubleshooting Basics

• Identify
• Define
• Locate
• Correct
• Verify
• Difference between LUCK and SKILL

11
OSPF Troubleshooting

• show ip ospf int
• show ip ospf nei
• debug ip ospf adj
• show int
• show ip route ltip_addressgt
• show ip ospf data

12
Troubleshooting OSPF

• C2513A sh ip ospf int e 0
• Ethernet0 is up, line protocol is up
• Internet Address 203.250.14.1 255.255.255.0,
  Area 0.0.0.0
• Process ID 10, Router ID 203.250.13.41, Network
  Type BROADCAST, Cost 10
• Transmit Delay is 1 sec, State BDR, Priority 1
• Designated Router (ID) 203.250.15.1, Interface
  address 203.250.14.2
• Backup Designated router (ID) 203.250.13.41,
  Interface address
• 203.250.14.1
• Timer intervals configured, Hello 10, Dead 40,
  Wait 40, Retransmit 5
• Hello due in 00002
• Neighbor Count is 3, Adjacent neighbor count is
  3
• Adjacent with neighbor 203.250.15.1
  (Designated Router)
• Loopback0 is up, line protocol is up
• Internet Address 203.250.13.41 255.255.255.255,
  Area 1
• Process ID 10, Router ID 203.250.13.41, Network
  Type LOOPBACK, Cost 1
• Loopback interface is treated as a stub Host

13
Troubleshooting OSPF

• sh ip ospf nei
• Neighbor ID Pri State Dead Time
  Address Interface
• 203.250.12.1 1 2WAY/DROTHER 00037
  203.250.14.3 Ethernet0
• 203.250.15.1 1 FULL/DR
  00036 203.250.14.2 Ethernet0
• 203.250.13.41 1 FULL/BDR
  00034 203.250.14.1 Ethernet0

14
Boston / NY PVC Issue

• Layer 9 hot potato
• (37) dual-homed remote sites
• Frame relay 64K CIR
• T1 PVC with no traffic

15
Large Potential Customer

• A solution we can demonstrate?
• Global Network
• Cisco 7507 ATM routers
• Sydney / Singapore ATM VCD

16
Happy Holidays

• Thanks for being such a great audience and dont
  forget to pickup a Cisco Router or Switch this
  season
• It makes a very thoughtful gift!