OSPF Lab 3-1 in official guide question.

adam-b

Hello Everyone.

I have configured the lab as shown in Figure 3-1 of the BSCI lab book. Please see the output of the following show ip ospf database command. Then compare it to the output of "show ip route" which follows. My question is why is the ospf learned route to the 10.1.100.0/24 network not showing up in the database? Thanks guys!

R3#show ip ospf data

OSPF Router with ID (10.1.3.1) (Process ID 1)

Router Link States (Area 0)

Link ID ADV Router Age Seq# Checksum Link count
10.1.1.1 10.1.1.1 172 0x80000009 0x004575 4
10.1.2.1 10.1.2.1 176 0x8000000A 0x007144 4
10.1.3.1 10.1.3.1 256 0x80000004 0x00B68D 2

Net Link States (Area 0)

Link ID ADV Router Age Seq# Checksum
10.1.200.3 10.1.3.1 1343 0x80000003 0x00BC67



R3#show ip route


Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 5 subnets, 2 masks
C 10.1.3.0/24 is directly connected, Loopback3
O 10.1.2.1/32 [110/2] via 10.1.200.2, 00:27:34, FastEthernet0/0
O 10.1.1.1/32 [110/2] via 10.1.200.1, 00:19:24, FastEthernet0/0
O 10.1.100.0/24 [110/65] via 10.1.200.2, 00:08:07, FastEthernet0/0
[110/65] via 10.1.200.1, 00:08:07, FastEthernet0/0
C 10.1.200.0/24 is directly connected, FastEthernet0/0

networker050184

It is included in one of your router LSAs. You can view it with the show ip ospf database router router-id. If there was more than one router on that segment it would show up under the type 2 LSAs.

kryolla

sh ip route 10.1.100.0

then sh ip os data router adv "advertising router from the above command"

It has to be in the database before it will even be put in the routing table

Rack1R3#sh ip route 155.1.5.0
Routing entry for 155.1.5.0/24
Known via "ospf 1", distance 110, metric 14, type intra area
Last update from 155.1.37.7 on Ethernet2/0, 13:43:37 ago
Routing Descriptor Blocks:
* 155.1.37.7, from 150.1.5.5, 13:43:37 ago, via Ethernet2/0
Route metric is 14, traffic share count is 1

Rack1R3#sh ip os da route ad
Rack1R3#sh ip os da route adv-router 150.1.5.5

OSPF Router with ID (150.1.3.3) (Process ID 1)

Router Link States (Area 0)

Routing Bit Set on this LSA
LS age: 1323
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 150.1.5.5
Advertising Router: 150.1.5.5
LS Seq Number: 80000169
Checksum: 0x514D
Length: 84
AS Boundary Router
Number of Links: 5

Link connected to: a Transit Network
(Link ID) Designated Router address: 155.1.0.5
(Link Data) Router Interface address: 155.1.0.5
Number of TOS metrics: 0
TOS 0 Metrics: 64

Link connected to: a Stub Network
(Link ID) Network/subnet number: 155.1.5.0
(Link Data) Network Mask: 255.255.255.0
Number of TOS metrics: 0
TOS 0 Metrics: 1

Link connected to: a Stub Network
(Link ID) Network/subnet number: 155.1.45.0
(Link Data) Network Mask: 255.255.255.0
Number of TOS metrics: 0
TOS 0 Metrics: 65

Link connected to: a Stub Network
(Link ID) Network/subnet number: 155.1.58.0
(Link Data) Network Mask: 255.255.255.0
Number of TOS metrics: 0
TOS 0 Metrics: 1

Link connected to: a Stub Network
(Link ID) Network/subnet number: 150.1.5.0
(Link Data) Network Mask: 255.255.255.0
Number of TOS metrics: 0
TOS 0 Metrics: 1


Rack1R3#

adam-b

Thanks to both of you for your replies. Both of your methods worked very nicely. What is the difference between "show ip ospf database router xxx.xxx.xxx" and "show ip ospf database router adv-router xxx.xxx.xxx" ? Thanks in advance

networker050184

adam-b wrote: »

Thanks to both of you for your replies. Both of your methods worked very nicely. What is the difference between "show ip ospf database router xxx.xxx.xxx" and "show ip ospf database router adv-router xxx.xxx.xxx" ? Thanks in advance

Nothing but an extra word in the command. The advertising-router ip and link state ID should always be the same as far as I know.

EDIT: Keep in mind that is for router LSAs. A network (or other type) LSA will have differing link state ID and advertising router.

adam-b

Ok thanks alot. I guese my questions are leading to the fact that i still dont feel as though i understand some of the details regarding the "router" and "network" lsa types. I understand that a router LSAs list all of the direct connected links to the advertising router. Are these propogated by the DR?

Also, why is a network lsa needed in addition to the router lsa?

Thanks alot for your help guys... I breezed through EIGRP but am finding OSPF a tad more complicated!

networker050184

adam-b wrote: »

Ok thanks alot. I guese my questions are leading to the fact that i still dont feel as though i understand some of the details regarding the "router" and "network" lsa types. I understand that a router LSAs list all of the direct connected links to the advertising router. Are these propogated by the DR?

Also, why is a network lsa needed in addition to the router lsa?

Thanks alot for your help guys... I breezed through EIGRP but am finding OSPF a tad more complicated!

Every router creates a router (type 1) LSA with its router ID and all connected links. These have nothing to do with a DR.

The DR on a segment creates a network (type 2) LSA with all routers connected to that segment.

adam-b

networker050184 wrote: »

Every router creates a router (type 1) LSA with its router ID and all connected links. These have nothing to do with a DR.

The DR on a segment creates a network (type 2) LSA with all routers connected to that segment.

Great! Couldn't all the routers connected to a given segment be determined solely based on the information contained within the type 1 LSAs? Im still uncertain why the network LSA is needed. Thanks.

EDIT: Are the type 1 LSA's only destined to the DR and BDR?

kryolla

how do you know what is connected on a given segment (lsa-2) and yes it is propagated by the dr to other segments and yes lsa-1 is only sent to the dr and bdr for multi-access segments. The database is a map of the area and a somewhat map of other area as you can do lsa-3,5 filtering and only know about lsa that abr is sending into the area so without any diagrams you should be able to read the database and map it out. Since all router are in your control you should be able to telnet to any router and get a perfect map of the area it belongs in and you would know what lsa are getting filtered

Routing Bit Set on this LSA
LS age: 748
Options: (No TOS-capability, DC)
LS Type: Network Links
Link State ID: 155.1.146.4 (address of Designated Router)
Advertising Router: 150.1.4.4
LS Seq Number: 8000000D
Checksum: 0x6812
Length: 36
Network Mask: /24
Attached Router: 150.1.4.4
Attached Router: 150.1.1.1
Attached Router: 150.1.6.6

adam-b

Thanks for your reply Kryolla.