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Panos2000
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Posts: 9
Joined: Fri Mar 18, 2005 1:15 am

OSPF regarding Areas

Sun Jul 08, 2018 12:04 pm

Image

For the example topology above:

R0
----
Area: Backbone, id: 0.0.0.0
Area: R0_lan_area, id: 0.0.0.1
Area: R0_wlan_area, id: 0.0.0.2
Network 10.1.1.0/30 --> Backbone
Network 10.1.1.4/30 --> Backbone
Network 10.1.1.8/30 --> Backbone
Network 10.1.1.12/30 --> Backbone
Network 10.1.10.0/24 --> R0_lan_area
Network 10.1.11.0/24 --> R0_wlan_area

R1
----
Area: Backbone, id: 0.0.0.0
Area: R1_lan_area, id: 0.0.0.1
Network 10.1.1.0/30 --> Backbone
Network 10.1.11.0/24 --> R1_lan_area

R2
----
Area: Backbone, id: 0.0.0.0
Area: R2_lan_area, id: 0.0.0.1
Network 10.1.1.4/30 --> Backbone
Network 10.1.12.0/24 --> R2_lan_area

R3
----
Area: Backbone, id: 0.0.0.0
Area: R3_lan_area, id: 0.0.0.1
Network 10.1.1.8/30 --> Backbone
Network 10.1.13.0/24 --> R3_lan_area

R4
----
Area: Backbone, id: 0.0.0.0
Area: R4_lan_area, id: 0.0.0.1
Network 10.1.1.12/30 --> Backbone
Network 10.1.14.0/24 --> R4_lan_area

On top of that:
R0 has a static route 0.0.0.0/0 with gateway 10.1.1.18 for the IPs that need internet that have the right routing mark and with masquerading
All routers have 0.0.0.0/0 with gateway the relevant IP of R0 for each router

Is this correct? The Internet access is OK but I still don't see all IPs under each router while I can ping them from the router itself...

I find a little confusing the example in the manual here https://wiki.mikrotik.com/wiki/Manual:OSPF-examples when they write:
/routing ospf network> add network=10.0.1.0/24 area=backbone
/routing ospf network> add network=10.1.2.0/30 area=area2
The /24 network to the Backbone and the /30 Network to the area?!

Or further up:
[admin@MikroTikR1] /routing ospf network> add network=210.13.1.0/28 area=backbone
[admin@MikroTikR1] /routing ospf network> add network=10.10.1.0/30 area=backbone
[admin@MikroTikR1] /routing ospf network> add network=10.10.1.4/30 area=backbone
Everything on the backbone? No areas?

Area Questions:
- Is an Area a separate entity for each router or is it something shared across routers in an OSPF Network?
- What about their IDs? Are they supposed to be unique for the whole network or for each router?
- For example: R0_lan_area --> id: 0.0.0.1, R1_lan_area --> id: 0.0.0.1 Is this OK or should they have different IDs?
- Does having the same id for different areas mean that they are going to be shared by OSPF meaning that users can see each other between those areas?

In my example above I have a central Router through which everything connects. What if I ALSO wanted to connect for example R1 <--> R3 on top of that? What would change in the OSPF configuration?

Thanks in advance for your valuable input!
 
Panos2000
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Posts: 9
Joined: Fri Mar 18, 2005 1:15 am

Re: OSPF regarding Areas

Wed Jul 11, 2018 8:31 pm

Is this question too complicated or just too naive to answer?...
 
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Anumrak
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Posts: 903
Joined: Fri Jul 28, 2017 2:53 pm

Re: OSPF regarding Areas

Thu Jul 12, 2018 9:15 am

Shared area is an area in which routers advertising LSA type 1 and 2. Router ID in OSPF process(OSPF Autonomous system) must be unique. Users of LAN of OSPF router can reach each other through LSA type 1 and 2 in each single area and via LSA type 3 in a different area, but these diff area must be connected to backbone area(0.0.0.0) directly or via virtual link.

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