不可比较的AS间的度量问题的解决办法
使用全互连的IBGP
打开always-compare-MED
打开deterministic-MED
把MED值重置为0
使用团体属性
Platform:cisco iou
step 1:load config file (basic_config.txt)
这时候请观察R1，R2，R3，R4去往7.7.7.7的下一跳。
根据上图所示，去往7.7.7.7 都不是最低MED的。
step 2:在R1,R2,R3,R4都输入 bgp always-compare-med ，再去查看R1
R1++++++++++++++++++++++++++++++++++++++++++++++++++++
interface Loopback0
ip address 1.1.1.1 255.255.255.255
!
interface Ethernet0/0
no sh
!
interface Ethernet0/0.12
encapsulation dot1Q 12
ip address 12.1.1.1 255.255.255.0
!
interface Ethernet0/0.13
encapsulation dot1Q 13
ip address 13.1.1.1 255.255.255.0
!
interface Ethernet0/0.14
encapsulation dot1Q 14
ip address 14.1.1.1 255.255.255.0
!
router ospf 100
network 0.0.0.0 255.255.255.255 area 0
!
router bgp 100
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 100
neighbor 2.2.2.2 update-source Loopback0
neighbor 2.2.2.2 route-reflector-client
neighbor 3.3.3.3 remote-as 100
neighbor 3.3.3.3 update-source Loopback0
neighbor 3.3.3.3 route-reflector-client
neighbor 4.4.4.4 remote-as 100
neighbor 4.4.4.4 update-source Loopback0
neighbor 4.4.4.4 route-reflector-client
no auto-summary
R2++++++++++++++++++++++++++++++++++++++++++++++
interface Loopback0
ip address 2.2.2.2 255.255.255.255
!
interface Ethernet0/0
no sh
!
interface Ethernet0/0.12
encapsulation dot1Q 12
ip address 12.1.1.2 255.255.255.0
!
interface Ethernet0/0.25
encapsulation dot1Q 25
ip address 25.1.1.2 255.255.255.0
!
router ospf 100
network 2.2.2.2 0.0.0.0 area 0
network 12.1.1.2 0.0.0.0 area 0
!
router bgp 100
bgp log-neighbor-changes
neighbor 1.1.1.1 remote-as 100
neighbor 1.1.1.1 update-source Loopback0
neighbor 1.1.1.1 next-hop-self
neighbor 25.1.1.5 remote-as 200
neighbor 25.1.1.5 route-map F5 in
no auto-summary
R3+++++++++++++++++++++++++++++++++++++++++++++++++++++
interface Loopback0
ip address 3.3.3.3 255.255.255.255
!
interface Ethernet0/0
no sh
!
interface Ethernet0/0.13
encapsulation dot1Q 13
ip address 13.1.1.3 255.255.255.0
!
interface Ethernet0/0.36
encapsulation dot1Q 36
ip address 36.1.1.3 255.255.255.0
!
router ospf 100
network 3.3.3.3 0.0.0.0 area 0
network 13.1.1.3 0.0.0.0 area 0
!
router bgp 100
bgp log-neighbor-changes
neighbor 1.1.1.1 remote-as 100
neighbor 1.1.1.1 update-source Loopback0
neighbor 1.1.1.1 next-hop-self
neighbor 36.1.1.6 remote-as 300
neighbor 36.1.1.6 route-map F6 in
no auto-summary
!
R4++++++++++++++++++++++++++++++++++++++++++++++++++++++++
interface Loopback0
ip address 4.4.4.4 255.255.255.255
!
interface Ethernet0/0
no sh
!
interface Ethernet0/0.14
encapsulation dot1Q 14
ip address 14.1.1.4 255.255.255.0
!
interface Ethernet0/0.46
encapsulation dot1Q 46
ip address 46.1.1.4 255.255.255.0
!
router ospf 100
network 4.4.4.4 0.0.0.0 area 0
network 14.1.1.4 0.0.0.0 area 0
!
router bgp 100
bgp log-neighbor-changes
neighbor 1.1.1.1 remote-as 100
neighbor 1.1.1.1 update-source Loopback0
neighbor 1.1.1.1 next-hop-self
neighbor 46.1.1.6 remote-as 300
neighbor 46.1.1.6 route-map F6 in
no auto-summary
R5++++++++++++++++++++++++++++++++++++++++++++++++++
interface Loopback0
ip address 5.5.5.5 255.255.255.255
!
interface Ethernet0/0
no sh
!
interface Ethernet0/0.25
encapsulation dot1Q 25
ip address 25.1.1.5 255.255.255.0
!
interface Ethernet0/0.57
encapsulation dot1Q 57
ip address 57.1.1.5 255.255.255.0
!
router bgp 200
bgp log-neighbor-changes
network 5.5.5.5 mask 255.255.255.255
neighbor 25.1.1.2 remote-as 100
neighbor 57.1.1.7 remote-as 400
no auto-summary
!
R6+++++++++++++++++++++++++++++++++++++++++++++++
interface Loopback0
ip address 6.6.6.6 255.255.255.255
!
interface Ethernet0/0
no sh
!
interface Ethernet0/0.36
encapsulation dot1Q 36
ip address 36.1.1.6 255.255.255.0
!
interface Ethernet0/0.46
encapsulation dot1Q 46
ip address 46.1.1.6 255.255.255.0
!
interface Ethernet0/0.67
encapsulation dot1Q 67
ip address 67.1.1.6 255.255.255.0
!
router bgp 300
bgp log-neighbor-changes
network 6.6.6.6 mask 255.255.255.255
neighbor 36.1.1.3 remote-as 100
neighbor 46.1.1.4 remote-as 100
no auto-summary
R7++++++++++++++++++++++++++++++++++++++++++++
interface Loopback0
ip address 7.7.7.7 255.255.255.255
!
interface Ethernet0/0
no sh
!
interface Ethernet0/0.57
encapsulation dot1Q 57
ip address 57.1.1.7 255.255.255.0
!
interface Ethernet0/0.67
encapsulation dot1Q 67
ip address 67.1.1.7 255.255.255.0
!
router bgp 400
bgp log-neighbor-changes
network 7.7.7.7 mask 255.255.255.255
neighbor 57.1.1.5 remote-as 200
neighbor 67.1.1.6 remote-as 300
no auto-summary