溫馨提示×
您好，登錄后才能下訂單哦！
點擊 登錄注冊 即表示同意《億速云用戶服務條款》
您好，登錄后才能下訂單哦！
1、as-path選路解析
| 屬性 | 傳播范圍 | 默認值 | 優先值 | 方向 | 備注 |
| weight | 本路由器 | 本路由器32768，其他路由器0 | 大值優先 | IN | CISCO私有 |
| Local preference | AS內部 | 100：邊界路由器，通告給IBGP鄰居，告知如何離開本AS | 大值優先 | OUT | |
| As path | AS之間 | 無 | 短優先 | IN、OUT |
修改As path值的方法:
方法一：在OUT方向上修改As path值，例如
ip prefix-list 1 seq 5 permit 33.33.33.0/24
route-map AS permit 10
match ip address prefix-list 1
set as-path prepend 2 2 2 2 2
route-map AS permit 20
router bgp 3
neighbor 23.1.1.2 route-map AS out
方法二：在IN方向上修改As path值，例如
2、實驗拓撲
3、基礎配置
R1配置
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配置
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配置
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配置
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、默認選路
根據BGP選路原則第八條可以知道，R4到達3.3.3.0/24、33.33.33.0/24都是經過R2。
5、在OUT方向上修改As path值
R4到達3.3.3.0/24、33.33.33.0/24都是經過R2，我們通過修改As path值將R4到達3.3.3.0/24經過R2、達到33.33.33.0/24都是經過R1。
R3配置
ip prefix-list 1 seq 5 permit 33.33.33.0/24
route-map AS permit 10
match ip address prefix-list 1
set as-path prepend 2 2 2 2 2
route-map AS permit 20
router bgp 3
neighbor 23.1.1.2 route-map AS out
6、在IN方向上修改As path值
R4到達3.3.3.0/24、33.33.33.0/24都是經過R2，我們通過修改As path值將R4到達3.3.3.0/24經過R2、達到33.33.33.0/24都是經過R1。
R2配置
ip prefix-list 1 seq 5 permit 33.33.33.0/24
route-map AS permit 10
match ip address prefix-list 1
set as-path prepend 2 2 2 2 2
route-map AS permit 20
router bgp 4
neighbor 23.1.1.3 route-map AS in
免責聲明：本站發布的內容（圖片、視頻和文字）以原創、轉載和分享為主，文章觀點不代表本網站立場，如果涉及侵權請聯系站長郵箱：is@yisu.com進行舉報，并提供相關證據，一經查實，將立刻刪除涉嫌侵權內容。
