BGP default-metric metric 实验
实验说明：
n
redistribute ospf 1— Assigns a metric of 0 to OSPF routes.
n
redistribute ospf 1 metric 5— Assigns a metric of 5 to OSPF routes.
n
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.
实验拓朴：
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
n
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
n
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
.