For additional information, see these resources:
■ “OSPF: Frequently Asked Questions” - http://www.cisco.com/en/US/tech/tk365/technologies_q_and_a_item09186a0080094704.shtml
■ “OSPF Not-So-Stubby Area (NSSA)” - www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094a88.shtml
■ “OSPF Design Guide” - www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a0080094e9e.shtml
■ “Designing Large-Scale IP Internetworks” - www.cisco.com/en/US/docs/internetworking/design/guide/nd2003.html
■ “Cisco IOS Software Releases 12.4 Mainline” - http://www.cisco.com/en/US/products/ps6350/tsd_products_support_series_home.html
■ Radia Perlman. Interconnections: Bridges, Routers, Switches, and Internetworking Protocols(2nd Edition), Addison-Wesley Professional (1999).
An excellent reference for understanding routing protocol sequence numbering and aging
OSPF Commands
Commands for verifying OSPF operation:
show ip protocols
show ip route
show ip route ospf
show ip ospf route (some platforms)
show ip ospf
show ip ospf database
show ip ospf interface
show ip ospf interface br
show ip ospf neighbor
show ip ospf virtual-links
debug ip packet ! disable cef before debug ip packet !!!!!
debug ip ospf events
debug ip ospf adj (auth)
debug ip ospf packet
Settings and filters
R6# sh ip proto
Routing Protocol is "ospf 1"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 6.6.6.6
Number of areas in this router is 2. 2 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
Routing on Interfaces Configured Explicitly (Area 8):
FastEthernet0/0
Routing on Interfaces Configured Explicitly (Area 95):
FastEthernet0/1
Reference bandwidth unit is 100 mbps
Routing Information Sources:
Gateway Distance Last Update
7.7.7.7 110 00:11:00
4.4.4.4 110 00:11:00
Distance: (default is 110)
Neighbors
R6#sh ip ospf nei
Neighbor ID Pri State Dead Time Address Interface
4.4.4.4 1 FULL/DROTHER 00:00:36 8.8.8.4 FastEthernet0/0
8.8.8.5 1 FULL/DR 00:00:35 8.8.8.5 FastEthernet0/0
21.21.21.21 1 FULL/BDR 00:00:37 172.21.21.21 FastEthernet0/1
Interfaces
R6# sh ip ospf int br
Interface PID Area IP Address/Mask Cost State Nbrs F/C
Fa0/0 1 8 8.8.8.6/24 1 BDR 2/2
Fa0/1 1 95 172.21.21.6/24 1 DR 1/1
Topology
1) Easy way
R6#sh ip route ospf
O IA 192.168.12.0/24 [110/2] via 8.8.8.4, 00:14:28, FastEthernet0/0
O E2 192.168.208.0/24 [110/10] via 8.8.8.4, 00:14:28, FastEthernet0/0
172.16.0.0/24 is subnetted, 1 subnets
R6#sh ip ospf route
OSPF Router with ID (6.6.6.6) (Process ID 1)
Area 8
Intra-area Route List
* 8.8.8.0/24, Intra, cost 1, area 8, Connected
via 8.8.8.6, FastEthernet0/0
Intra-area Router Path List
i 4.4.4.4 [1] via 8.8.8.4, FastEthernet0/0, ABR, Area 8, SPF 2
Inter-area Route List
*> 10.100.0.0/24, Inter, cost 3, area 8
via 8.8.8.4, FastEthernet0/0
*> 10.120.0.0/24, Inter, cost 3, area 8
via 8.8.8.4, FastEthernet0/0
2) Hard way
R6# sh ip ospf data | exc Checksum
OSPF Router with ID (6.6.6.6) (Process ID 1)
Router Link States (Area 8)
4.4.4.4 4.4.4.4 974 0x80000002 0x0008CF 1
6.6.6.6 6.6.6.6 954 0x80000002 0x00883E 1
8.8.8.5 8.8.8.5 975 0x80000002 0x0012AB 1
Net Link States (Area 8)
8.8.8.5 8.8.8.5 955 0x80000002 0x00BCF8
Summary Net Link States (Area 8)
10.100.0.0 4.4.4.4 960 0x80000001 0x00EDCE
10.120.0.0 4.4.4.4 960 0x80000001 0x00FCAB
R6# sh ip ospf database summary | inc Mask|State|Summary
Summary Net Link States (Area 8)
LS Type: Summary Links(Network)
Link State ID: 10.100.0.0 (summary Network Number)
Network Mask: /24
LS Type: Summary Links(Network)
Link State ID: 10.120.0.0 (summary Network Number)
Network Mask: /24
LS Type: Summary Links(Network)
R6# sh ip ospf database extern | inc Mask|State|Summary
Type-5 AS External Link States
Link State ID: 192.168.0.0 (External Network Number )
Network Mask: /16
Link State ID: 192.168.50.0 (External Network Number )
Network Mask: /24
Link State ID: 192.168.200.0 (External Network Number )
Network Mask: /24
FAQs
Typical Reasons for OSPF Neighbor Problems link
| Reason for Neighbor Adjacency Problem | Commands for Diagnosing the Problem |
|---|---|
| OSPF is not configured on one of the routers. | show ip ospf |
| OSPF is not enabled on an interface where it is needed. | show ip ospf interface |
| OSPF HELLO or Dead timer interval values are mismatched. | show ip ospf interface |
| ip ospf network-type mismatch on the adjoining interfaces. | show ip ospf interface |
| MTU mismatch between neighboring interfaces. | show interface <int-type><int-num> |
| OSPF area-type is stub on one neighbor, but the adjoining neighbor in the same area is not configured for stub. | show running-config show ip ospf interface |
| OSPF neighbors have duplicate Router IDs. | show ip ospf show ip ospf interface |
| OSPF is configured on the secondary network of the neighbor, but not on the primary network. This is an illegal configuration which prevents OSPF from being enabled on the interface. | show ip ospf interface show running-config |
| OSPF HELLOs are not not processed due to a lack of resources, such as high CPU utilization or not enough memory. | show memory summary show memory processor |
| An underlying Layer problem is preventing OSPF HELLOs from being received. | show interface |
Note: In order to aviod the MTU check while you establish ospf adjacency, you possibly need to configure the ip ospf mtu-ignore command in interface configuration mode.
OSPF DESIGN GUIDE
http://nobbyville.com/OSPF/OSPF2.html
OSPF: Frequently Asked Questions
http://nobbyville.com/OSPF/OSPF6.html
OSPF: Frequently Asked Questions (@ cisco.com)
http://www.cisco.com/en/US/tech/tk365/technologies_q_and_a_item09186a0080094704.shtml
LSA Type 4
http://packetlife.net/blog/2008/apr/21/where-are-type-4-lsas-generated/
http://aconaway.com/2010/06/20/route-notes-ospf-filtering-and-summarization/
Memory Tables
- OSPF Point to Multipoint Non Broadcast over Frame Relay (backup link - topology and pdf)
- OSPF Point to Multipoint Non Broadcast over Frame Relay (backup link - topology and pdf)
http://simplecisco.wordpress.com/tag/ccnp-route/
Commands
Show routes in OSPF domain
R12# sh ip ospf data summary | inc State|Mask
Summary Net Link States (Area 0)
Link State ID: 1.1.0.0 (summary Network Number)
Network Mask: /16
Link State ID: 8.8.8.0 (summary Network Number)
Network Mask: /24
Link State ID: 10.100.0.0 (summary Network Number)
Network Mask: /24
Link State ID: 10.120.0.0 (summary Network Number)
Network Mask: /24
Link State ID: 10.130.0.0 (summary Network Number)
Network Mask: /24
Link State ID: 10.200.0.0 (summary Network Number)
Network Mask: /24
Link State ID: 192.168.23.0 (summary Network Number)
Network Mask: /24
R12# sh ip ospf data external | inc State|Mask
Type-5 AS External Link States
Link State ID: 192.168.0.0 (External Network Number )
Network Mask: /16
Link State ID: 192.168.50.0 (External Network Number )
Network Mask: /24
Link State ID: 192.168.200.0 (External Network Number )
Network Mask: /24
Link State ID: 192.168.205.0 (External Network Number )
Network Mask: /24
Link State ID: 192.168.208.0 (External Network Number )
Network Mask: /24
R4#sh ip route ospf
1.0.0.0/16 is subnetted, 1 subnets
O IA 1.1.0.0 [110/2001] via 192.168.12.1, 00:11:44, FastEthernet0/0
O E2 192.168.208.0/24 [110/10] via 192.168.12.7, 1d06h, FastEthernet0/0
172.16.0.0/24 is subnetted, 1 subnets
O 172.16.1.0 [110/2] via 192.168.12.1, 2d22h, FastEthernet0/0
O E2 192.168.200.0/24 [110/10] via 192.168.12.7, 1d06h, FastEthernet0/0
10.0.0.0/24 is subnetted, 4 subnets
O IA 10.100.0.0 [110/2] via 192.168.12.7, 1d06h, FastEthernet0/0
O IA 10.120.0.0 [110/2] via 192.168.12.7, 1d06h, FastEthernet0/0
O IA 10.130.0.0 [110/2] via 192.168.12.7, 1d06h, FastEthernet0/0
O IA 10.200.0.0 [110/2] via 192.168.12.7, 1d06h, FastEthernet0/0
O IA 192.168.23.0/24 [110/3] via 192.168.12.1, 2d22h, FastEthernet0/0
O E2 192.168.205.0/24 [110/10] via 192.168.12.7, 1d06h, FastEthernet0/0
O E2 192.168.50.0/24 [110/10] via 192.168.12.7, 1d06h, FastEthernet0/0
O E2 192.168.0.0/16 [110/5] via 192.168.12.7, 1d06h, FastEthernet0/0
R4#
Labs
- OSPF Point to Multipoint Non Broadcast over Frame Relay (backup link - topology and pdf)
- OSPF Point to Multipoint Non Broadcast over Frame Relay (backup link - topology and pdf)
http://simplecisco.wordpress.com/tag/ccnp-route/
