BGP選路屬性修改 iou

首先對於ibg而言修改度值值 抓 抓 到之後 修改度量值

bgp會跟route-map一起出現

選路原則

路由有被加入路由表的資格，才能比。
思科華爲前8步一樣：

1. weight 思科私有 華爲：優先級 隻影響本地
   默認始發：32768 非本地：0
2. LP 本地優先級 公認屬性 發送給ibgp鄰居會攜帶local preference . 用它實現 從內到外 從哪個出口出。只會影響as內的 針對ebgp鄰居做入方向修改，可
3. route originate 始發優於穿越 更多用來環防
4. as path 比長短 公認強制
5. 起源屬性 i>e>incomplete
6. MED 繼承igp的度量值 從外到內 哪個入口入
7. e>ibgp
8. 去往邊界的度量值
9. 要麼都是聚合，要麼不是可以配置負載均衡
10. 早學到的優
11. router id小的優
12. cluster-list做了路由反射器纔有
    實驗：

看拓撲 配地址

內網igp

r1

router eigrp 90
no auto-summary 
eigrp router 1.1.1.1
netwrork 1.1.1.1 
network 13.1.1.1 

r3

router eigrp 90
no auto-summary 
eigrp router 3.3.3.3
network 3.3.3.3 
network 13.1.1.3 
netwrok 34.1.1.3

r4

router eigrp 90
no auto-summary 
eigrp router 4.4.4.4
network 4.4.4.4
netwrok 34.1.1.4

bgp

r2起bgp

router bgp 2 
no auto-summary
no synchronization
bgp router-id  2.2.2.2
neighbor 12.1.1.1 remote-as 10
neighbor 24.1.1.4  remote-as 10 

r1和r4建ebgp

router bgp 10
no auto-summary
no synchronization
bgp router-id  
neighbor   as 2

r1 ibgp

neighbor 3.3.3.3 remote-as 10
neighbor 3.3.3.3 update-source loopback 0
neighbor 3.3.3.3 next-hop-self 

r4 ibgp

neighbor 3.3.3.3 remote-as 10
neighbor 3.3.3.3 update-source loopback 0
neighbor 3.3.3.3 next-hop-self 

r3 ibgp

router bgp 10
no auto-summary
no synchronization
bgp router-id  3.3.3.3 
neighbor 1.1.1.1 remote-as 10

neighbor 4.4.4.4 remote-as 10 
neighbor 1.1.1.1 update-source loopback0 

ebgp :
neighbor 35.1.1.5 remote-as 5

r5 ebgp

router bgp 5 
no auto-summary
no synchronization
bgp router-id  5.5.5.5
neighbor 35.1.1.3  remote-as 10

實驗：
先在r2上通告兩條路由

int loo 8
ip add 8.8.8.8  255.255.255.0
router bgp 2 
netwrok 8.8.8.0 mask 255.255.255.0
network 2.2.2.0 mask 255.255.255.0

修改權重

進程下
neighbor x.x.x.x weight 
是針對所有路由

針對 某一條路由
r3

access-list 2 permit 2.2.2.0
route-map  w permit 10
match ip address 2  //調用acl
set weight 1
exit
route-map w permit 20 
exit 

router bgp 10
neighbor 1.1.1.1 route-map w in 

用lp實現
r1

ip prefix-list 2 seq 10 permit 2.2.2.0/24 
route-map lp permit 10
match ip address prefix-list 2
set local  101
exit
route-map lp permit 20
exit
router bgp 10
neighbor 12.1.1.2 route-map lp in 

起源屬性

r4

ip prefix-list 2 seq 10 permit 2.2.2.0/24
route-map o permit 10
match ip address prefix-list 2 
set origin egp 10
exit
route-map o permit 20
exit
router	bgp 10 
neighbor 3.3.3.3 route-map o out 
end

med 修改
先創建環回口
r3

int loo 9 
ip address 9.9.9.9 255.255.255.0
router bgp 10 
network 9.9.9.0 mask 255.255.255.0

bgp bestpath med missing-as-worst 收到不帶med的路由，給他設置一個默認最大值

r1
ip prefix-list 9 seq 10 permit 9.9.9.0/24
route-map med permit 10
match ip address prefix-list 9
set metric 10 
exit
route-map o permit 20
exit
router	bgp 10 
neighbor 12.1.1.2 rouete-map med out