Understand Open Shortest Path First (ospf) Design Guide

Router Links
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
203.0.113.41 203.0.113.41 179 0x80000029 0x9ADA 3
203.0.113.67 203.0.113.67 675 0x800001E2 0xDD23 1
Start with the router links. There are two entries listed for 203.0.113.41 and 203.0.113.67, these
are the RIDs of the two routers in area 0. The number of links in area 0 for each router is also
indicated. RTA has three links to area 0 and RTC has one link. A detailed view of the RTC router
links:
RTC#show ip ospf database router 203.0.113.67
OSPF Router with ID (203.0.113.67) (Process ID 10)
Router Link States (Area 1)
LS age: 1169
Options: (No TOS-capability)
LS Type: Router Links
Link State ID: 203.0.113.67
Advertising Router: 203.0.113.67
LS Seq Number: 80000008
Checksum: 0xB112
Length: 48
Area Border Router
Number of Links: 2
Link connected to: another Router (point-to-point)
(Link ID) Neighbor Router ID: 203.0.113.16
(Link Data) Router Interface address: 203.0.113.151
Number of TOS metrics: 0
TOS 0 Metrics: 64
Link connected to: a Stub Network
(Link ID) Network/subnet number: 203.0.113.150
(Link Data) Network Mask: 255.255.255.192
Number of TOS metrics: 0
TOS 0 Metrics: 64
One thing to note here is that OSPF generates an extra stub link for each point-to-point interface.
Do not get confused if you see the link count larger than the number of physical interfaces.
Router Link States (Area 0)
LS age: 1227
Options: (No TOS-capability)
LS Type: Router Links
Link State ID: 203.0.113.67
Advertising Router: 203.0.113.67
LS Seq Number: 80000003
Checksum: 0xA041
Length: 36
Area Border Router
 Number of Links: 1

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