HCNP the principle and configuration of OSPF protocol for learning notes 7-OSPF interval routing

To avoid inter-zone loops, OSPF does not allow routing information to be published directly between two non-backbone zones, allowing routing information to be published only within a region or between the backbone and non-backbone regions. Therefore, each zone boundary router (ABR) must be connected to the backbone area.

Inter-zone routing via NETWORK-SUMMARY-LSA Declaration

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Taking the network segment 10.1.1.0/24 as an example, the process of inter-zone route publishing is as follows:

• First, RTB (area 1 's ABR) publishes the routing information for that segment into the backbone area. 650) this.width=650; "src="/e/u261/themes/default/images/spacer.gif "style=" border:1px solid rgb (221,221,221); background-position:50% 50%;background-repeat:no-repeat; "alt=" Spacer.gif "/>650" this.width=650; "src="/e/u261/ Themes/default/images/spacer.gif "style=" border:1px solid rgb (221,221,221); background-position:50% 50%; Background-repeat:no-repeat, "alt=" Spacer.gif "/>650" this.width=650; "src="/e/u261/themes/default/images/ Spacer.gif "style=" border:1px solid rgb (221,221,221); background-position:50% 50%;background-repeat:no-repeat; alt= "Spacer.gif"/>

• The RTC then learns from the backbone area the routing information that RTB publishes about the segment 10.1.1.0/24.

• Finally, RTC regenerates a new NETWORK-SUMMARY-LSA and publishes it to area 2

Configuration command:

When there are multiple regions, you need to declare different networks within different regions

If RTB is connected to two area, it is necessary to declare the 10.2.1.0/24 network in AREA0 and declare 10.1.1.0/24 in AREA1.

Virtual connection

There are no backbone areas in the network (area 0), how to publish routing information between these three regions?

You only need to configure a virtual connection between the two area border routers (RTA and RTB). A virtual connection is part of the backbone area, and all virtual connections belong to Zone 0. 650) this.width=650; "src="/e/u261/themes/default/images/spacer.gif "style=" Background:url ("/e/u261/lang /zh-cn/images/localimage.png ") no-repeat center;border:1px solid #ddd;" alt= "Spacer.gif"/>

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Vlink-peer Router-id: When configuring a virtual connection, the peer-to-peer router is used to represent the peer router ID.

A virtual connection needs to be configured on two ABR.

Routing aggregation: Configuring routing aggregation on ABR

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Configuration command:

[Rtb-ospf-1-area-0.0.0.1]abr-summary 20.1.1.0 255.255.255.0

After the configuration is complete, the restart takes effect [r1]reset OSPF process

Abr-summary ip-address Mask [Advertise | not-advertise] [cost]

Advertise: Broadcast the summary information to this converged segment route.

Notadvertise: Do not broadcast the summary information to this aggregation segment route.

Cost: Sets the overhead for the aggregation route.

Example: Virtual connection + route aggregation, topology in attachment

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• The AR2 route aggregation is only passed within the region, so the aggregated entries can be viewed in the AR3 routing table

• In AR5 to get the aggregated route, you need to also configure the route aggregation on AR4, in the case of virtual connection, AR4 is equivalent to the ABR between AREA2 and area0.

• ABR is responsible for distributing routing information within the region

HCNP the principle and configuration of OSPF protocol for learning notes 7-OSPF interval routing