MPLS L3 跨域 optionB 配置

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mpls跨域optionB

　　optionB的核心思想是私网路由传递过程是 PE-ASBR1-ASBR2-PE2 在传递过程中私网标签发生了变化（由ASBR重新分配了私网标签），而在数据平面（不考虑PHP机制）当数据包到达ASBR1时标签存在公网标签和私网标签两层，当转发给ASBR2时只有一层由ASBR2分配的私网标签，通过EBGP隧道迭代直接到达ASBR2，ASBR2再把私网标签替换成PE分配的标签并压入公网标签后转发。

　　所以在optionB中私网标签一共有三个，数据包标签最少时只有一层私网标签

　　optionB的缺点是ASBR设备需要维护到用户侧的VPNV4路由，占用大量设备资源，所以现网中如果使用optionB做为跨域方案，建议ASBR设备只做MPLS设备来使用

拓扑

编址

	G0/0/0	G0/0/1	loopback0
CE1	10.0.0.1/30		192.168.0.1
PE1	12.1.1.1/24	10.0.0.2/30	1.1.1.1
P1	12.1.1.2/24	23.1.1.2/24	2.2.2.2
ASBR1	34.1.1.3/24	23.1.1.3/24	3.3.3.3
ASBR2	34.1.1.4/24	45.1.1.4/24	4.4.4.4
P2	56.1.1.5/24	45.1.1.5/24	5.5.5.5
PE2	56.1.1.6/24	10.10.10.2/30	6.6.6.6
CE1	10.10.10.1/30		192.168.1.1

底层互联地址ospf,域内mpls ldp配置略
1. 　　查看ASBR路由表
2. 　　查看ASBR mpls lsp
PE配置VPN端口接入CE
1. 　　PE1
  ip vpn-instance vpn1
  ipv4-family
  route-distinguisher 100:1
  vpn-target 100:1 export-extcommunity
  vpn-target 100:1 import-extcommunity
  
  interface GigabitEthernet0/0/1
  ip binding vpn-instance vpn1
  ip address 10.0.0.2 255.255.255.252
  
  bgp 100
  #
  ipv4-family unicast
  undo synchronization
  #
  ipv4-family vpn-instance vpn1
  peer 10.0.0.1 as-number 300
  
  CE1
  
  bgp 300
  peer 10.0.0.2 as-number 100
  #
  ipv4-family unicast
  undo synchronization
  network 192.168.0.1 255.255.255.255
  peer 10.0.0.2 enable
  #
2. PE2
  
  ip vpn-instance vpn1
  ipv4-family
  route-distinguisher 100:1
  vpn-target 100:1 export-extcommunity
  vpn-target 100:1 import-extcommunity
  
  interface GigabitEthernet0/0/1
  ip binding vpn-instance vpn1
  ip address 10.10.10.2 255.255.255.252
  
  bgp 200
  #
  ipv4-family unicast
  undo synchronization
  #
  ipv4-family vpn-instance vpn1
  peer 10.10.10.1 as-number 400
查看BGP状态与路由
1. 　　PE1
2. PE2
PE与ASBR间建立IBGP-VPNV4邻居关系，传递私网路由，注意ASBR一定要undo policy vpn-target，否则会因为VPN RT值不匹配导致无法安装私网路由

ASBR
bgp 100
peer 1.1.1.1 as-number 100
peer 1.1.1.1 connect-interface LoopBack0
#
ipv4-family unicast
undo synchronization
peer 1.1.1.1 enable
peer 34.1.1.4 enable
#
ipv4-family vpnv4
undo policy vpn-target
peer 1.1.1.1 enable
PE

bgp 100
peer 3.3.3.3 as-number 100
peer 3.3.3.3 connect-interface LoopBack0
#
ipv4-family unicast
undo synchronization
peer 3.3.3.3 enable
#
ipv4-family vpnv4
policy vpn-target
peer 3.3.3.3 enable
查看ASBR是否正常接收到PE传递的私网路由
ASBR间建立EBGP-VPNV4邻居关系，并配置替换外层VPN标签，使公网LSP完整
ASBR1

bgp 100
peer 1.1.1.1 as-number 100
peer 1.1.1.1 connect-interface LoopBack0
peer 34.1.1.4 as-number 200
#
ipv4-family unicast
undo synchronization
peer 1.1.1.1 enable
peer 1.1.1.1 route-policy to-pe export
peer 1.1.1.1 label-route-capability
peer 34.1.1.4 enable
peer 34.1.1.4 route-policy to-asbr export
peer 34.1.1.4 label-route-capability
#
ipv4-family vpnv4
undo policy vpn-target
peer 1.1.1.1 enable
peer 34.1.1.4 enable

route-policy to-asbr permit node 10
apply mpls-label
#
route-policy to-pe permit node 10
if-match mpls-label
apply mpls-label

ASBR2

bgp 200
peer 6.6.6.6 as-number 200
peer 6.6.6.6 connect-interface LoopBack0
peer 34.1.1.3 as-number 100
#
ipv4-family unicast
undo synchronization
peer 6.6.6.6 enable
peer 6.6.6.6 route-policy to-pe export
peer 6.6.6.6 label-route-capability
peer 34.1.1.3 enable
peer 34.1.1.3 route-policy to-asbr export
peer 34.1.1.3 label-route-capability
#
ipv4-family vpnv4
undo policy vpn-target
peer 6.6.6.6 enable
peer 34.1.1.3 enable

route-policy to-asbr permit node 10
apply mpls-label
#
route-policy to-pe permit node 10
if-match mpls-label
apply mpls-label

查看两端ASBR路由

查看两端ASBR MPLS LSP
查看CE设备路由表，并测试连通性