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11-07-2017 12:16 PM - edited 03-08-2019 12:39 PM
Why Type-2 LSA are propagated in between R1 and R5(Area 1)? here is my configuration
R1#show ip ospf database OSPF Router with ID (192.168.10.1) (Process ID 1) Router Link States (Area 0) Link ID ADV Router Age Seq# Checksum Link count 192.168.10.1 192.168.10.1 274 0x80000002 0x00DA78 1 192.168.10.2 192.168.10.2 276 0x80000002 0x00D57B 1 192.168.10.3 192.168.10.3 275 0x80000003 0x00D477 1 192.168.10.4 192.168.10.4 275 0x80000002 0x009C6B 2 Net Link States (Area 0) Link ID ADV Router Age Seq# Checksum 192.168.10.4 192.168.10.4 275 0x80000001 0x00FF6B Summary Net Link States (Area 0) Link ID ADV Router Age Seq# Checksum 10.10.1.0 192.168.10.1 310 0x80000001 0x008F1A 10.20.1.0 192.168.10.3 303 0x80000002 0x000993 Router Link States (Area 1) Link ID ADV Router Age Seq# Checksum Link count 10.10.1.2 10.10.1.2 256 0x80000002 0x006E5F 1 192.168.10.1 192.168.10.1 257 0x80000002 0x00B85A 1 Net Link States (Area 1) Link ID ADV Router Age Seq# Checksum 10.10.1.1 192.168.10.1 260 0x80000001 0x0036ED Summary Net Link States (Area 1) Link ID ADV Router Age Seq# Checksum 10.20.1.0 192.168.10.1 324 0x80000001 0x007B1A 10.30.1.0 192.168.10.1 326 0x80000001 0x000388 192.168.10.0 192.168.10.1 367 0x80000001 0x0075D5
At R5,
R5#show ip ospf database router 192.168.10.1 OSPF Router with ID (10.10.1.2) (Process ID 1) Router Link States (Area 1) Routing Bit Set on this LSA LS age: 1232 Options: (No TOS-capability, DC) LS Type: Router Links Link State ID: 192.168.10.1 Advertising Router: 192.168.10.1 LS Seq Number: 80000002 Checksum: 0xB85A Length: 36 Area Border Router Number of Links: 1 Link connected to: a Transit Network (Link ID) Designated Router address: 10.10.1.1 (Link Data) Router Interface address: 10.10.1.1 Number of TOS metrics: 0 TOS 0 Metrics: 10
You can see in above show command, the R1 router is connected to Transit Network. It is p2p link, isn't it?
And there is a DR in Area 1?
R5#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 192.168.10.1 1 FULL/DR 00:00:31 10.10.1.1 FastEthernet0/1
Or should configure those links as p2p explicitly?
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11-07-2017 03:07 PM
Hi,
In OSPF, Ethernet links are treated as Broadcast network type even if they physical connection is point-to-point.
Why Type-2 LSA are propagated in between R1 and R5(Area 1)?
Since the connection between R1 and R5 is using Ethernet link (where the default network type is Broadcast), you will have DR/BDR election and also Type-2 LSA.
You can see in above show command, the R1 router is connected to Transit Network. It is p2p link, isn't it? And there is a DR in Area 1? Or should configure those links as p2p explicitly?
Yes, you will need to change your network type to "point-to-point" if you do not want to have Type-2 LSA, and no DR/BDR election. The command is:
int fa0/1
ip ospf network point-to-point
!
Check the change by running "sh ip ospf interface fa0/1".
HTH,
Meheretab
Meheretab
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11-07-2017 03:07 PM
Hi,
In OSPF, Ethernet links are treated as Broadcast network type even if they physical connection is point-to-point.
Why Type-2 LSA are propagated in between R1 and R5(Area 1)?
Since the connection between R1 and R5 is using Ethernet link (where the default network type is Broadcast), you will have DR/BDR election and also Type-2 LSA.
You can see in above show command, the R1 router is connected to Transit Network. It is p2p link, isn't it? And there is a DR in Area 1? Or should configure those links as p2p explicitly?
Yes, you will need to change your network type to "point-to-point" if you do not want to have Type-2 LSA, and no DR/BDR election. The command is:
int fa0/1
ip ospf network point-to-point
!
Check the change by running "sh ip ospf interface fa0/1".
HTH,
Meheretab
Meheretab
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11-07-2017 04:49 PM - edited 11-07-2017 05:13 PM
Hi,
The transit networks represents the networks with the capabilities to transport traffic that is not locally generated or locally destined. Router LSA considered the local connected subnets as stub type.
This link could be useful:
http://thenetworksherpa.com/ospf-making-sense-of-router-lsa-point-to-point-links/
:-)
>> Marcar como útil o contestado, si la respuesta resolvió la duda, esto ayuda a futuras consultas de otros miembros de la comunidad. <<
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11-07-2017 05:18 PM - edited 11-07-2017 05:19 PM
Hello
Please review this excellant post by the Mr Peter Paulch - Very definative answer to your query. - Here
It will explain in much more detail then I ever could thats for sure!
res
Paul
Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.
Kind Regards
Paul
