MPLS ×××數(shù)據(jù)詳細(xì)轉(zhuǎn)發(fā)流程示意圖：

配置思路：

在自治系統(tǒng)AS100中配置IGP，使得兩臺(tái)PE路由器的lo 0接口路由可達(dá)；

兩臺(tái)PE路由器路由可達(dá)后，在兩臺(tái)PE路由器之間建立MP-iBGP鄰居關(guān)系，用來(lái)傳輸×××V4路由；

AS100中所有P路由器和PE路由器運(yùn)行MPLS，并使用LDP來(lái)給非BGP路由分發(fā)標(biāo)簽；

在PE路由器和CE路由器之間運(yùn)行ospf路由協(xié)議，使得PE路由器的VRF路由表可以學(xué)習(xí)到CE路由器的路由；

將PE路由器VRF學(xué)習(xí)到的路由重分發(fā)進(jìn)BGP，使得對(duì)端PE路由器可以通過(guò)MP-iBGP鄰居關(guān)系學(xué)習(xí)到×××V4路由；

將BGP路由在PE路由器上充分發(fā)進(jìn)ce端ospf，使得CE路由器可以學(xué)習(xí)到相互的私有路由

上述拓?fù)浠九渲?/font>

R1配置：

ip cef

!

ip vrf cisco

?rd100:1

?route-target export 100:2

?route-target import 100:2

!

mpls label range 100 199

mpls label protocol ldp

?

interface Loopback0

?ipaddress 1.1.1.1 255.255.255.255

!

interface Ethernet0/0

?ipvrf forwarding cisco

?ipaddress 10.1.15.1 255.255.255.0

?half-duplex

!

interface Ethernet0/1

?ipaddress 10.1.12.1 255.255.255.0

?half-duplex

?mplslabel protocol ldp

?mplsip

!????

router ospf 1 vrf cisco

?log-adjacency-changes

?redistribute bgp 100 subnets

?network 10.1.15.0 0.0.0.255 area 0

!

router ospf 100

?router-id 1.1.1.1

?log-adjacency-changes

?network 1.1.1.1 0.0.0.0 area 0

?network 10.1.12.0 0.0.0.255 area 0

!

router bgp 100

?bgprouter-id 1.1.1.1

?bgplog-neighbor-changes

?neighbor 4.4.4.4 remote-as 100

?neighbor 4.4.4.4 update-source Loopback0

?!

?address-family ipv4

?neighbor 4.4.4.4 activate

?noauto-summary

?nosynchronization

?exit-address-family

?!???????

?address-family ***v4

?neighbor 4.4.4.4 activate

?neighbor 4.4.4.4 send-community extended

?exit-address-family

?!

?address-family ipv4 vrf cisco

?redistribute ospf 1 vrf cisco match internalexternal 1 external 2

?nosynchronization

?exit-address-family

!

no ip http server

!

mpls ldp router-id Loopback0

?

R2配置：

ip cef

!

mpls label range 200 299

mpls label protocol ldp

!

interface Loopback0

?ipaddress 2.2.2.2 255.255.255.255

!

interface Ethernet0/0

?ipaddress 10.1.23.2 255.255.255.0

?half-duplex

?mplslabel protocol ldp

?mplsip

!

interface Ethernet0/1

?ipaddress 10.1.12.2 255.255.255.0

?half-duplex

?mplslabel protocol ldp

?mplsip

!

router ospf 100

?router-id 2.2.2.2

?log-adjacency-changes

?network 2.2.2.2 0.0.0.0 area 0

?network 10.1.12.0 0.0.0.255 area 0

?network 10.1.23.0 0.0.0.255 area 0

!

no ip http server

!

mpls ldp router-id Loopback0

?

R3配置：

ip cef

!

mpls label range 300 399

mpls label protocol ldp

!

interface Loopback0

?ipaddress 3.3.3.3 255.255.255.255

!

interface Ethernet0/0

?ipaddress 10.1.23.3 255.255.255.0

?half-duplex

?mplslabel protocol ldp

?mplsip

!

interface Ethernet0/1

?ipaddress 10.1.34.3 255.255.255.0

?half-duplex

?mplslabel protocol ldp

?mplsip

!

router ospf 100

?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

?network 10.1.34.0 0.0.0.255 area 0

!

no ip http server

!

mpls ldp router-id Loopback0

?

R4配置：

ip cef

!

ip vrf cisco

?rd100:4

?route-target export 100:2

?route-target import 100:2

!

mpls label range 400 499

mpls label protocol ldp

!

interface Loopback0

?ipaddress 4.4.4.4 255.255.255.255

!

interface Ethernet0/0

?ipvrf forwarding cisco

?ip address10.1.46.4 255.255.255.0

?half-duplex

!

interface Ethernet0/1

?ipaddress 10.1.34.4 255.255.255.0

?half-duplex

?mplslabel protocol ldp

?mplsip

!????????

router ospf 1 vrf cisco

?log-adjacency-changes

?redistribute bgp 100 subnets

?network 10.1.46.0 0.0.0.255 area 0

!

router ospf 100

?router-id 4.4.4.4

?log-adjacency-changes

?network 4.4.4.4 0.0.0.0 area 0

?network 10.1.34.0 0.0.0.255 area 0

!

router bgp 100

?bgplog-neighbor-changes

?neighbor 1.1.1.1 remote-as 100

?neighbor 1.1.1.1 update-source Loopback0

?!

?address-family ipv4

?neighbor 1.1.1.1 activate

?noauto-summary

?nosynchronization

?exit-address-family

?!

?address-family ***v4

?neighbor 1.1.1.1 activate

?neighbor 1.1.1.1 send-community extended

?exit-address-family

?!

?address-family ipv4 vrf cisco

?redistribute ospf 1 vrf cisco match internalexternal 1 external 2

?nosynchronization

?exit-address-family

!

mpls ldp router-id Loopback0

?

R5配置：

ip cef

interface Loopback0

?ipaddress 5.5.5.5 255.255.255.255

!

interface Ethernet0/0

?ipaddress 10.1.15.5 255.255.255.0

?half-duplex

!

router ospf 1

?router-id 5.5.5.5

?log-adjacency-changes

?network 5.5.5.5 0.0.0.0 area 0

?network 10.1.15.0 0.0.0.255 area 0

?

R6配置：

ip cef

interface Loopback0

?ipaddress 6.6.6.6 255.255.255.255

!

interface Ethernet0/0

?ipaddress 10.1.46.6 255.255.255.0

?half-duplex

!

router ospf 1

?router-id 6.6.6.6

?log-adjacency-changes

?network 6.6.6.6 0.0.0.0 area 0

?network10.1.46.0 0.0.0.255 area 0

分析：

當(dāng)R1和R4建立MP-iBG鄰居關(guān)系后，R1在將從VRF cisco中學(xué)習(xí)到的路由5.5.5.5/32發(fā)送給R4時(shí)將攜帶RD 100：1，并且分配標(biāo)簽為106，如下：

R1#show?ip bgp? ***v4 rd 100:1 labels

??Network????????? Next Hop????? In label/Out label

RouteDistinguisher: 100:1(cisco)

?? 5.5.5.5/32?????? 10.1.15.5?????? 106/nolabel

R4#SHOw?ip bgp? ***v4? rd 100:1 labels

??Network????????? Next Hop????? In label/Out label

Route Distinguisher: 100:1

?? 5.5.5.5/32?????? 1.1.1.1???????? nolabel/106

注意：BGP只會(huì)為每一個(gè)×××V4前綴分配一個(gè)標(biāo)簽，這個(gè)標(biāo)簽用來(lái)說(shuō)明報(bào)文的下一跳是誰(shuí)，也就是說(shuō)如果×××V4在MP-BGP傳輸?shù)倪^(guò)程中，如果×××V4前綴的下一跳不發(fā)生變化，那么途徑的BGP路由器將沒(méi)有權(quán)利修改標(biāo)簽。

?

以下是MP-iBGP在***v4路由更新時(shí)的調(diào)試信息：

*Mar 1 00:06:27.167: ***:bgp_***v4_alloc_tag route_tag_change for cisco:5.5.5.5/255.255.255.255

*Mar? 1 00:06:27.167: ***:tag_***_find_route_tags: 100:1:5.5.5.5

*Mar? 1 00:06:27.171: ***:intag=106, outtag=unknown, outtag owner=BGP

?

*Mar?1 00:04:29.171: ***: bgp_***v4_bnetinit: 100:4:6.6.6.6/32

*Mar?1 00:04:29.175: BGP: Accepted path from 4.4.4.4

*Mar? 1 00:04:42.131: ***:bgp_***v4_bnetinit: 100:1:6.6.6.6/32

*Mar? 1 00:04:42.283: ***:tag_***_find_route_tags: 100:1:6.6.6.6

*Mar? 1 00:04:42.287: ***:intag=***-route, outtag=405, outtag owner=BGP

可以看到R1學(xué)習(xí)到的100:4:6.6.6.6的outlable標(biāo)簽為405，是R4所分配

R1給前綴100:1:5.5.5.5，分配的in lable 標(biāo)簽為106

?

在R5上查看，可以看到R5已經(jīng)學(xué)習(xí)到了6.6.6.6/32的路由信息，R6同理會(huì)學(xué)到5.5.5.5/32的路由

R5#show?ip route

Codes: C - connected, S - static, R - RIP,M - mobile, B - BGP

??????D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

??????N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

??????E1 - OSPF external type 1, E2 - OSPF external type 2

??????i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

??????ia - IS-IS inter area, * - candidate default, U - per-user static route

??????o - ODR, P - periodic downloaded static route

?

Gateway of last resort is not set

?

????5.0.0.0/32 is subnetted, 1 subnets

C??????5.5.5.5 is directly connected, Loopback0

????6.0.0.0/32 is subnetted, 1 subnets

O IA??? 6.6.6.6 [110/21] via10.1.15.1, 00:13:02, Ethernet0/0

????10.0.0.0/24 is subnetted, 2 subnets

C??????10.1.15.0 is directly connected, Ethernet0/0

O IA???10.1.46.0 [110/11] via 10.1.15.1, 00:13:02, Ethernet0/0

你會(huì)發(fā)現(xiàn)從MP-iBGP重分發(fā)進(jìn)入的路由是域間路由標(biāo)識(shí)IA，原因如下：

為OSPF工作的BGP擴(kuò)展屬性使得OSPF路由可以完全的在遠(yuǎn)端PE路由器上重建，路由類(lèi)型讓遠(yuǎn)端PE路由器了解到什么類(lèi)型的路由在OSPF中通告。如果是類(lèi)型1和2或者3的話(huà)，遠(yuǎn)程PE路由器將會(huì)通告一條域間匯總路由到OSPF中。

?

在PE路由器R1上查看VRF路由表：

R1#show ?ip route ?vrf cisco

Routing Table: cisco

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

? ? ? ?D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area?

? ? ? ?N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

? ? ? ?E1 - OSPF external type 1, E2 - OSPF external type 2

? ? ? ?i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

? ? ? ?ia - IS-IS inter area, * - candidate default, U - per-user static route

? ? ? ?o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

? ? ?5.0.0.0/32 is subnetted, 1 subnets

O ? ? ? 5.5.5.5 [110/11] via 10.1.15.5, 00:55:43, Ethernet0/0

? ? ?6.0.0.0/32 is subnetted, 1 subnets

B ? ? ? 6.6.6.6 [200/11] via 4.4.4.4, 00:57:23

? ? ?10.0.0.0/24 is subnetted, 2 subnets

C ? ? ? 10.1.15.0 is directly connected, Ethernet0/0

B ? ? ? 10.1.46.0 [200/0] via 4.4.4.4, 00:57:23

可以看到去往6.6.6.6/32的路由為BGP路由，并且下一跳為4.4.4.4

查看6.6.6.6的*** 標(biāo)簽：

R1#show ip bgp ?***v4 ?rd 100:4 LAbels?

? ?Network ? ? ? ? ?Next Hop ? ? ?In label/Out label

Route Distinguisher: 100:4

? ?6.6.6.6/32 ? ? ? 4.4.4.4 ? ? ? ? nolabel/405

可以看到6.6.6.6的*** outlable標(biāo)簽為405，當(dāng)數(shù)據(jù)在進(jìn)入VRF cisco后將添加底部標(biāo)簽405

查看4.4.4.4的LDP標(biāo)簽

R1#show ?mpls ?forwarding-table?

Local ?Outgoing ? ?Prefix ? ? ? ? ? ?Bytes tag ?Outgoing ? Next Hop ? ?

tag ? ?tag or VC ? or Tunnel Id ? ? ?switched ? interface ? ? ? ? ? ? ?

100 ? ?Pop tag ? ? 10.1.23.0/24 ? ? ?0 ? ? ? ? ?Et0/1 ? ? ?10.1.12.2 ? ?

101 ? ?203 ? ? ? ? 10.1.34.0/24 ? ? ?0 ? ? ? ? ?Et0/1 ? ? ?10.1.12.2 ? ?

102 ? ?Pop tag ? ? 2.2.2.2/32 ? ? ? ?0 ? ? ? ? ?Et0/1 ? ? ?10.1.12.2 ? ?

103 ? ?201 ? ? ? ? 3.3.3.3/32 ? ? ? ?0 ? ? ? ? ?Et0/1 ? ? ?10.1.12.2 ? ?

104 ? ?202 ? ? ? ? 4.4.4.4/32 ? ? ? ?0 ? ? ? ? ?Et0/1 ? ? ?10.1.12.2 ? ?

105 ? ?Aggregate ? 10.1.15.0/24[V] ? 0 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?

106 ? ?Untagged ? ?5.5.5.5/32[V] ? ? 570 ? ? ? ?Et0/0 ? ? ?10.1.15.5

在加入底部標(biāo)簽405后將數(shù)據(jù)將會(huì)壓入遞歸查詢(xún)到的下一跳4.4.4.4的出站標(biāo)簽202，

在P路由器R2上查看路由表：

R2#show ip route

Codes: C - connected, S - static, R - RIP,M - mobile, B - BGP

??????D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

??????N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

??????E1 - OSPF external type 1, E2 - OSPF external type 2

??????i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

??????ia - IS-IS inter area, * - candidate default, U - per-user static route

??????o - ODR, P - periodic downloaded static route

?

Gateway of last resort is not set

?

????1.0.0.0/32 is subnetted, 1 subnets

O??????1.1.1.1 [110/11] via 10.1.12.1, 00:13:16, Ethernet0/1

????2.0.0.0/32 is subnetted, 1 subnets

C??????2.2.2.2 is directly connected, Loopback0

????3.0.0.0/32 is subnetted, 1 subnets

O??????3.3.3.3 [110/11] via 10.1.23.3, 00:13:16, Ethernet0/0

????4.0.0.0/32 is subnetted, 1 subnets

O??????4.4.4.4 [110/21] via 10.1.23.3, 00:13:16, Ethernet0/0

????10.0.0.0/24 is subnetted, 3 subnets

C??????10.1.12.0 is directly connected, Ethernet0/1

C??????10.1.23.0 is directly connected, Ethernet0/0

O??????10.1.34.0 [110/20] via 10.1.23.3, 00:13:17, Ethernet0/0

可以看到R2上不存在5.5.5.5和6.6.6.6的路由信息，所以在AS100中用戶(hù)數(shù)據(jù)的轉(zhuǎn)發(fā)只能靠標(biāo)簽轉(zhuǎn)發(fā)來(lái)完成，二不是IP路由轉(zhuǎn)發(fā)

查看R2的標(biāo)簽轉(zhuǎn)發(fā)信息庫(kù)，如下：

R2#show mpls? forwarding-table

Local?Outgoing??? Prefix??????????? Bytes tag? Outgoing??Next Hop???

tag???tag or VC?? or Tunnel Id????? switched??interface?????????????

200???Pop tag???? 1.1.1.1/32??????? 14931????? Et0/1?????10.1.12.1???

201???Pop tag???? 3.3.3.3/32??????? 0 ?????????Et0/0????? 10.1.23.3???

202???302???????? 4.4.4.4/32??????? 19345????? Et0/0?????10.1.23.3???

203???Pop tag???? 10.1.34.0/24????? 0?????????Et0/0????? 10.1.23.3???

可以看到R2對(duì)于路由4.4.4.4的本地標(biāo)簽為202，遠(yuǎn)程標(biāo)簽為302，在數(shù)據(jù)進(jìn)入p路由器R2后，將完全按照標(biāo)簽進(jìn)行轉(zhuǎn)發(fā)，而不是路由轉(zhuǎn)發(fā)，從而實(shí)現(xiàn)通信。

Ping測(cè)試：

R5#ping 6.6.6.6 source? 5.5.5.5

?

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 6.6.6.6,timeout is 2 seconds:

Packet sent with a source address of5.5.5.5

!!!!!

Success rate is 100 percent (5/5),round-trip min/avg/max = 56/91/112 ms

可以看到?jīng)]有問(wèn)題，能夠通信