BGP选路属性修改 iou

首先对于ibg而言修改度值值 抓 抓 到之后 修改度量值

bgp会跟route-map一起出现

选路原则

路由有被加入路由表的资格，才能比。
思科华为前8步一样：

1. weight 思科私有 华为：优先级 只影响本地
   默认始发：32768 非本地：0
2. LP 本地优先级 公认属性 发送给ibgp邻居会携带local preference . 用它实现 从内到外 从哪个出口出。只会影响as内的 针对ebgp邻居做入方向修改，可
3. route originate 始发优于穿越 更多用来环防
4. as path 比长短 公认强制
5. 起源属性 i>e>incomplete
6. MED 继承igp的度量值 从外到内 哪个入口入
7. e>ibgp
8. 去往边界的度量值
9. 要么都是聚合，要么不是可以配置负载均衡
10. 早学到的优
11. router id小的优
12. cluster-list做了路由反射器才有
    实验：

看拓扑 配地址

内网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

实验：
先在r2上通告两条路由

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

修改权重

进程下
neighbor x.x.x.x weight 
是针对所有路由

针对 某一条路由
r3

access-list 2 permit 2.2.2.0
route-map  w permit 10
match ip address 2  //调用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实现
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 

起源属性

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
先创建环回口
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 收到不带med的路由，给他设置一个默认最大值

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