Multi-region ospf

Ospf multi-region and sub-region

Key design points of the region:

1. backbone area 0

2. Other regions must be connected to the perimeter of the backbone area 0.

Other regions cannot be directly connected

Requirements for area 0:

Fast and stable. The core of a vro with a few vrouters

This topic uses an experiment as an example:

The topology is as follows:

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The four routers ar1, ar2, ar3, and ar4 at the top of this experiment use the ospf Protocol to implement multi-region ospf. The following three ar2, ar5, and ar6 use the rip Protocol.

The specific configuration is as follows:

Ar1:

[Huawei] sysname r1

[R1] int eth0/0/0

[R1-Ethernet0/0/0] ip add 192.168.1.1 24

[R1-Ethernet0/0/0] loopback local

[R1-Ethernet0/0/0] int s0/0/0

[R1-Serial0/0/0] ip add 192.168.2.1 24

[R1] ospf

[R1-ospf-1] area 1

[R1-ospf-1-area-0.0.0.1] network 192.168.1.1 0.0.0.0

[R1-ospf-1-area-0.0.0.1] network 192.168.2.1 0.0.0.0

Ar2

[Huawei] sysname 2

[2] int s0/0/0

[2-Serial0/0/0] ip add 192.168.2.2 24

[2-Serial0/0/0] int s0/0/2

[2-Serial0/0/2] ip add 192.168.3.1 24

[2-Serial0/0/2] int s0/0/1

[2-Serial0/0/1] ip add 192.168.6.1 24

[2] ospf

[2-ospf-1] area 1

[2-ospf-1-area-0.0.0.1] network 192.168.2.2 0.0.0.0

[2-ospf-1-area-0.0.0.1] q

[2-ospf-1]

[2-ospf-1] area 0

[2-ospf-1-area-0.0.0.0] network 192.168.3.1 0.0.0.0

[2] rip

[2-rip-1] network 192.168.6.0

Ar3

[Huawei] sysname r3

[R3] int s0/0/0

[R3-Serial0/0/0] ip add 192.168.3.2 24

[R3-Serial0/0/0] int s0/0/1

[R3-Serial0/0/1] ip add 192.168.4.1 24

[R3] ospf

[R3-ospf-1] area 0

[R3-ospf-1-area-0.0.0.0] network 192.168.3.2 0.0.0.0

[R3-ospf-1] area 2

[R3-ospf-1-area-0.0.0.2] network 192.168.4.1 0.0.0.0

Ar4

[Huawei] sysname r4

[R4-Serial0/0/0]

[R4-Serial0/0/0] ip add 192.168.4.2 24

[R4-Serial0/0/0] int e0/0/0

[R4-Ethernet0/0/0] ip add 192.168.5.1 24

[R4-Ethernet0/0/0] loopback local

[R4] ospf

[R4-ospf-1] area 2

[R4-ospf-1-area-0.0.0.2] network 192.168.4.2 0.0.0.0

[R4-ospf-1-area-0.0.0.2] network 192.168.5.1 0.0.0.0

Ar5

[Huawei] sysname r5

[R5] int s0/0/0

[R5-Serial0/0/0] ip add 192.168.6.2 24

[R5-Serial0/0/0] int s0/0/1

[R5-Serial0/0/1] ip add 192.168.7.1 24

[R5] rip

[R5-rip-1] network 192.168.6.0

[R5-rip-1] network 192.168.7.0

Ar6

[Huawei] sysname r6

[R6] int s0/0/0

[R6-Serial0/0/0] ip add 192.168.7.2 24

[R6-Serial0/0/0] int e0/0/0

[R6-Ethernet0/0/0] ip add 192.168.8.1 24

[R6-Ethernet0/0/0] loopback local

[R6] rip

[R6-rip-1] network 192.168.7.0

[R6-rip-1] network 192.168.8.0

Check the route table of the six routers after the configuration.

Ar1

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Learn three ospf routes: 1, 2, 3, 4, and 5)

Ar2

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I learned 3 about ospf and 2 about 1, 2, 3, 4, 5, 6, 7, and 8 of rip)

Ar3

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Learn 3 ospf route entries 1, 2, 3, 4, and 5)

Ar4

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Learn 3 ospf route entries 1, 2, 3, 4, and 5)

Ar5

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Learn a rip route 6, 7, and 8)

Ar6

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Learn a rip route 6, 7, and 8)

Now, there is no problem with all the routers, but why do I learn all the routes except ar2, such as routes 1, 3, and 4, only routes 1-5, but ospf, 5 and 6 only learn routes of 6 to 8. What about rip?

In fact, ospf and rip in the routing protocol are two different routing protocols. They can only learn the routing information of their own protocols, but cannot learn the routing information of other routing protocols. So, we need to re-release the route and publish the rip information to the ospf network.

Note: The re-release of a route can only be set on the Protocol's VBR, that is, ar2

The configuration is as follows:

Ar2

[2] ospf

[2-ospf-1] import-route rip

That's all.

Let's take a look at the ar4 route table and see if there is any information about the routes 7 and 8.

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6-8 Route information appears. If you do not find 6, the reason is very simple, because we write what we learned through rip injection, and 6 is directly connected, so if there is no 6, you can add another command,

[2] ospf

[2-ospf-1] import-route direct

That's all.

Now, we can ping 7.1 on ar4, but it still won't pass. This is because we only have to go, but we have no way back. We certainly cannot, what should we do now?

If we can do the same as above, but there are too many route entries, so we can release a default route on ar2, generate a default route on rip

[2] rip

[2-rip-1] default-route originate

Check the route table of ar6 and check whether the default route is learned.

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Ping8.1 on ar4 to check whether the connection is successful

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Ping1.1 on ar6

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Now, we think there are too many route entries on ar4, including those from different domains and from outside of yu. How can we make Inter-Domain and non-domain reception unavailable, but instead of a default route? In this case, we need to create the detail area.

Requirements for the detail area:

To do this on the VBR IN THE REGION

Run the xiangying command on the vro in the region.

Ar3

[R4] ospf

[R4-ospf-1] stub-router

Ar4

[R4] ospf

[R4-ospf-1] stub-router

Ar4 route table

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Ping7.1

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