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BGP default-metric metric 实验

实验说明:
1. redistribute ospf 1 — Assigns a metric of 0 to OSPF routes.
2. redistribute ospf 1 metric 5 — Assigns a metric of 5 to OSPF routes. 
3. redistribute ospf 1 metric 5
   redistribute static
   default-metric 10 — Assigns a metric of 5 to OSPF routes and a metric of 10 to static routes.
 
 
实验拓扑:
 
R1-R2-R3
 
 
实验配置:
R1和R2 起EBGP邻居关系 ,R2 与R3起OSPF邻居关系.
 
R2 BGP中通告路由 ,配置default-metric
1. network 通告
Lo0 2.2.2.2/32 默认 metric
Lo1 22.22.22.22/32 并加 route-map 设置 metric

2. 重分布通告
Redistribute ospf 1 + route-map 精确匹配 3.3.3.3/32 默认 metric
Redistribute static 设置 metric (静态路由 33.33.33.33/32)
 
R1配置:
interface Loopback0
ip address 1.1.1.1 255.255.255.255
!
interface Serial1/1
ip address 10.1.12.1 255.255.255.0
!
router bgp 1
bgp router-id 1.1.1.1
bgp log-neighbor-changes
neighbor 10.1.12.2 remote-as 2
no auto-summary
!
 
R2配置:
interface Loopback0
ip address 2.2.2.2 255.255.255.255
!
interface Serial1/0
ip address 10.1.12.2 255.255.255.0
!
interface Serial1/1
ip address 10.1.23.2 255.255.255.0
!
router ospf 1
router-id 2.2.2.2
log-adjacency-changes
network 10.1.23.0 0.0.0.255 area 0
!
router bgp 2
no synchronization
bgp router-id 2.2.2.2
bgp log-neighbor-changes
network 2.2.2.2 mask 255.255.255.255
network 22.22.22.22 mask 255.255.255.255 route-map metric
redistribute static metric 200
redistribute ospf 1 route-map ospf
neighbor 10.1.12.1 remote-as 1
default-metric 100
no auto-summary
!
ip classless
ip route 33.33.33.33 255.255.255.255 Serial1/1
no ip http server
!
!
ip prefix-list 1 seq 5 permit 3.3.3.3/32
route-map metric permit 10
set metric 300
!
route-map ospf permit 10
match ip address prefix-list 1
!
 
R3配置:
interface Loopback0
ip address 3.3.3.3 255.255.255.255
!
interface Loopback1
ip address 33.33.33.33 255.255.255.255
!
interface Serial1/0
ip address 10.1.23.3 255.255.255.0
!
router ospf 1
router-id 3.3.3.3
log-adjacency-changes
network 3.3.3.3 0.0.0.0 area 0
network 10.1.23.0 0.0.0.255 area 0
!
 
实验现象:
R1#sh ip bgp
BGP table version is 26, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete
 
     Network   Next Hop   Metric   LocPrf   Weight   Path
*> 2.2.2.2/32 10.1.12.2 0 0 2 i
*> 3.3.3.3/32 10.1.12.2 100 0 2 ?
*> 22.22.22.22/32 10.1.12.2 300 0 2 i
*> 33.33.33.33/32 10.1.12.2 200 0 2 ?
R1#
 
R2#sh ip bgp
BGP table version is 5, local router ID is 2.2.2.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete
 
Network Next Hop Metric LocPrf Weight Path
*> 2.2.2.2/32 0.0.0.0 0 32768 i
*> 3.3.3.3/32 10.1.23.3 100 32768 ?
*> 22.22.22.22/32 0.0.0.0 300 32768 i
*> 33.33.33.33/32 0.0.0.0 200 32768 ?
R2#
 
 
实验结论:
default-metric 命令作用
1. 只作用于重分布路由时.
因为 2.2.2.2/32 路由 metric 仍为 0 ,命令未生效 ; 3.3.3.3/32 metric 值被default-metric 命令改为 100.
2. 当重分布路由时,手工指定的 metric 值 (例如redistribute static metric 200, 或 + route-map 设置 metric值同样效果) 会优先于default-metric 值 .