Shulou(Shulou.com)06/01 Report--

1. Local preference routing analysis

Attribute

Spread range

Default value

Priority value direction

Note: weight this router this router is 32768, other routers 0 large value priority INCISCO private

Local preferenceAS Internal 100th: border router, advertised to IBGP neighbors, telling how to leave this AS large value priority OUT

How to modify the Local preference value:

Method 1: modify all the Local preference values of routes advertised to IBGP neighbors, for example:

Router bgp 4

Bgp default local-preference 125

Method 2: partially modify the Local preference value of routes advertised to IBGP neighbors, for example:

2. Experimental topology

3. Basic configuration

R1 configuration

Interface Loopback0

Ip address 1.1.1.1 255.255.255.0

Interface Serial0/0

Ip address 13.1.1.1 255.255.255.0

Interface Serial0/1

Ip address 14.1.1.1 255.255.255.0

Router ospf 110

Router-id 1.1.1.1

Log-adjacency-changes

Network 1.1.1.0 0.0.0.255 area 0

Network 14.1.1.0 0.0.0.255 area 0

Router bgp 4

No synchronization

Bgp router-id 1.1.1.1

Neighbor 4.4.4.4 remote-as 4

Neighbor 4.4.4.4 update-source Loopback0

Neighbor 4.4.4.4 next-hop-self

Neighbor 13.1.1.3 remote-as 3

No auto-summary

R2 configuration

Interface Loopback0

Ip address 2.2.2.2 255.255.255.0

Interface Serial0/1

Ip address 23.1.1.2 255.255.255.0

Interface FastEthernet1/0

Ip address 24.1.1.2 255.255.255.0

Router ospf 110

Router-id 2.2.2.2

Network 2.2.2.0 0.0.0.255 area 0

Network 24.1.1.0 0.0.0.255 area 0

Router bgp 4

No synchronization

Bgp router-id 2.2.2.2

Neighbor 4.4.4.4 remote-as 4

Neighbor 4.4.4.4 update-source Loopback0

Neighbor 4.4.4.4 next-hop-self

Neighbor 23.1.1.3 remote-as 3

No auto-summary

R3 configuration

Interface Loopback0

Ip address 3.3.3.3 255.255.255.0

Interface Loopback1

Ip address 33.33.33.33 255.255.255.0

Interface Serial0/0

Ip address 13.1.1.3 255.255.255.0

Interface Serial0/1

Ip address 23.1.1.3 255.255.255.0router bgp 3

No synchronization

Bgp router-id 3.3.3.3

Network 3.3.3.0 mask 255.255.255.0

Network 33.33.33.0 mask 255.255.255.0

Neighbor 13.1.1.1 remote-as 4

Neighbor 23.1.1.2 remote-as 4

No auto-summary

R4 configuration

Interface Loopback0

Ip address 4.4.4.4 255.255.255.0

Interface Serial0/1

Ip address 14.1.1.4 255.255.255.0

Interface FastEthernet1/0

Ip address 24.1.1.4 255.255.255.0

Router ospf 110

Router-id 4.4.4.4

Network 4.4.4.0 0.0.0.255 area 0

Network 14.1.1.0 0.0.0.255 area 0

Network 24.1.1.0 0.0.0.255 area 0

Router bgp 4

No synchronization

Bgp router-id 4.4.4.4

Neighbor 1.1.1.1 remote-as 4

Neighbor 1.1.1.1 update-source Loopback0

Neighbor 2.2.2.2 remote-as 4

Neighbor 2.2.2.2 update-source Loopback0

No auto-summary

4. Default routing

According to the eighth rule of BGP routing principle, R4 reaches 3.3.3.0 pick 24 and 33.33.33 pick 24 all pass through R2.

5. Modify the Local preference values of all routes advertised to IBGP neighbors

From the front can R4 to 3.3.3.0ax 24, 33.33.330C24 all go through R2, we change the Local cover value to make R4 reach 3.3.3.0Universe 24, 33.33.0Universe 24 all pass through R1.

R4 configuration

Router bgp 4

Bgp default local-preference 125

6. Partially modify the Local preference value of routes advertised to IBGP neighbors

R4 to 3.3.3.0Compact 24 and 33.33.330Universe 24 are all through R2. We change the Local promise value to make R4 reach 3.3.3.0Compact 24 through R2 and 33.33.33.0 Universe 24 through R1.

R4 configuration

Ip prefix-list 1 seq 5 permit 33.33.33.0/24

No cdp log mismatch duplex

Route-map L permit 10

Match ip address prefix-list 1

Set local-preference 125

Route-map L permit 20

Router bgp 4

Neighbor 4.4.4.4 route-map L out

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