BGP的基本原理

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汤姆一通LAB 2014-04-15 14:53:31 博主文章分类：技术原创 ©著作权

文章标签 network router interface domain 文章分类 网络安全

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IPA-taskpacket001：BGP的基本原理实验一：BGP路由传递原则

实验目标：掌握BGP的路由传递原则

实验TOP：

基本配置

hostname R1

no ip domain lookup

interface Loopback0

ipaddress 1.1.1.1 255.255.255.0

interface Loopback10

ipaddress 10.10.10.10 255.255.255.0

ipospf network point-to-point

interface Serial1/0

ipaddress 12.1.1.1 255.255.255.0

interface Serial1/1

ipaddress 13.1.1.1 255.255.255.0

router ospf 10

router-id 1.1.1.1

network 10.10.10.0 0.0.0.255 area 0

network 12.1.1.0 0.0.0.255 area 0

network 13.1.1.0 0.0.0.255 area 0

router bgp 65001

nosynchronization

bgprouter-id 1.1.1.1

network 1.1.1.0 mask 255.255.255.0

neighbor 12.1.1.2 remote-as 65001

neighbor 13.1.1.3 remote-as 65001

noauto-summary

hostname R2

no ip domain lookup

interface Loopback0

ipaddress 2.2.2.2 255.255.255.0

interface Loopback10

ipaddress 20.20.20.20 255.255.255.0

ipospf network point-to-point

interface Serial1/0

ipaddress 24.2.2.2 255.255.255.0

interface Serial1/1

ipaddress 12.1.1.2 255.255.255.0

router ospf 10

router-id 2.2.2.2

network 12.1.1.0 0.0.0.255 area 0

network 20.20.20.0 0.0.0.255 area 0

network 24.2.2.0 0.0.0.255 area 0

router bgp 65001

nosynchronization

bgprouter-id 2.2.2.2

network 2.2.2.0 mask 255.255.255.0

neighbor12.1.1.1 remote-as 65001

neighbor 24.2.2.4 remote-as 65001

noauto-summary

hostname R3

no ip domain lookup

interface Loopback0

ipaddress 3.3.3.3 255.255.255.0

interface Loopback10

ipaddress 30.30.30.30 255.255.255.0

ipospf network point-to-point

interface Serial1/1

ipaddress 13.1.1.3 255.255.255.0

interface Serial1/0

ipaddress 34.3.3.3 255.255.255.0

router ospf 10

router-id 3.3.3.3

network 13.1.1.0 0.0.0.255 area 0

network 30.30.30.0 0.0.0.255 area 0

network34.3.3.0 0.0.0.255 area 0

router bgp 65001

nosynchronization

bgprouter-id 3.3.3.3

network 3.3.3.0 mask 255.255.255.0

neighbor 13.1.1.1 remote-as 65001

neighbor 34.3.3.4 remote-as 65001

no auto-summary

hostname R4

no ip domain lookup

interface Loopback0

ipaddress 4.4.4.4 255.255.255.0

interface Loopback10

ipaddress 40.40.40.40 255.255.255.0

ipospf network point-to-point

interface Serial1/0

ipaddress 24.2.2.4 255.255.255.0

interface Serial1/1

ipaddress 34.3.3.4 255.255.255.0

Interface Serial1/2

Ip address 45.4.4.4 255.255.255.0

Interface Serial1/3

Ip address 46.4.4.4 255.255.255.0

router ospf 10

router-id 4.4.4.4

network 40.40.40.0 0.0.0.255 area 0

network 24.2.2.0 0.0.0.255 area 0

network 34.3.3.0 0.0.0.255 area 0

router bgp 65001

nosynchronization

bgprouter-id 4.4.4.4

network 4.4.4.0 mask 255.255.255.0

neighbor 24.2.2.2 remote-as 65001

neighbor 34.3.3.3 remote-as 65001

neighbor 45.4.4.5 remote-as 65002

neighbor 46.4.4.6 remote-as 65003

noauto-summary

Hostname R5

no ip domain lookup

interface Loopback0

ipaddress 5.5.5.5 255.255.255.0

interface Serial1/0

ipaddress 45.4.4.5 255.255.255.0

router bgp 65002

nosynchronization

bgprouter-id 5.5.5.5

network 5.5.5.0 mask 255.255.255.0

neighbor 45.4.4.4 remote-as 65001

noauto-summary

hostnameR6

interfaceLoopback0

ip address 6.6.6.6 255.255.255.0

interfaceSerial1/0

ip address 46.4.4.6 255.255.255.0

routerbgp 65003

no synchronization

bgp router-id 6.6.6.6

network 6.6.6.0 mask 255.255.255.0

neighbor 46.4.4.4 remote-as 65001

no auto-summary

批注：路由器接口默认是关闭的，所以应将对应的接口开启

基本配置完成之后，我们开始检查BGP对等体关系是否正常建立

R1#show ip bgp summary

BGP router identifier 1.1.1.1, local AS number 65001

BGP table version is 4, main routing table version 4

3 network entries using 303 bytes of memory

3 path entries using 144 bytes of memory

2 BGP path attribute entries using 120 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 567 total bytes of memory

BGP activity 3/0 prefixes, 3/0 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd

12.1.1.2 4 65001 10 10 4 0 0 00:05:28 1

13.1.1.3 4 65001 9 9 4 0 0 00:04:42 1

R1#

//R1此时已经正常与R2和R3建立iBGP对等体关系

R2#show ip bgp summary

BGP router identifier 2.2.2.2, local AS number 65001

BGP table version is 4, main routing table version 4

5 network entries using 505 bytes of memory

5 path entries using 240 bytes of memory

4 BGP path attribute entries using 240 bytes of memory

2 BGP AS-PATH entries using 48 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 1033 total bytes of memory

BGP activity 5/0 prefixes, 5/0 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd

12.1.1.1 4 65001 11 11 4 0 0 00:06:13 1

24.2.2.4 4 65001 11 9 4 0 0 00:04:51 3

R2#

//R2此时已经正常与R1和R4建立iBGP对等体关系

R3#show ip bgp summary

BGP router identifier 3.3.3.3, local AS number 65001

BGP table version is 4, main routing table version 4

5 network entries using 505 bytes of memory

5 path entries using 240 bytes of memory

4 BGP path attribute entries using 240 bytes of memory

2 BGP AS-PATH entries using 48 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 1033 total bytes of memory

BGP activity 5/0 prefixes, 5/0 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd

13.1.1.1 4 65001 10 10 4 0 0 00:05:53 1

34.3.3.4 4 65001 12 10 4 0 0 00:05:16 3

R3#

//R3此时已经正常与R1和R4建立iBGP对等体关系

R4#show ip bgp summary

BGP router identifier 4.4.4.4, local AS number 65001

BGP table version is 6, main routing table version 6

5 network entries using 505 bytes of memory

5 path entries using 240 bytes of memory

4 BGP path attribute entries using 240 bytes of memory

2 BGP AS-PATH entries using 48 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 1033 total bytes of memory

BGP activity 5/0 prefixes, 5/0 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd

24.2.2.2 4 65001 11 13 6 0 0 00:06:13 1

34.3.3.3 4 65001 11 13 6 0 0 00:06:13 1

45.4.4.5 4 65002 9 11 6 0 0 00:04:34 1

46.4.4.6 4 65003 9 11 6 0 0 00:04:10 1

R4#

//R4此时已经正常与R2和R3建立iBGP对等体关系，并且与R5和R6建立eBGP对等体关系

R5#show ip bgp summary

BGP router identifier 5.5.5.5, local AS number 65002

BGP table version is 6, main routing table version 6

5 network entries using 505 bytes of memory

5 path entries using 240 bytes of memory

4 BGP path attribute entries using 240 bytes of memory

2 BGP AS-PATH entries using 48 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 1033 total bytes of memory

BGP activity 5/0 prefixes, 5/0 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd

45.4.4.4 4 65001 11 9 6 0 0 00:04:53 4

R5#

//R5此时已经正常与R4建立eBGP对等体关系

R6#show ip bgp summary

BGP router identifier 6.6.6.6, local AS number 65003

BGP table version is 6, main routing table version 6

5 network entries using 505 bytes of memory

5 path entries using 240 bytes of memory

4 BGP path attribute entries using 240 bytes of memory

2 BGP AS-PATH entries using 48 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 1033 total bytes of memory

BGP activity 5/0 prefixes, 5/0 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd

46.4.4.4 4 65001 11 9 6 0 0 00:04:56 4

R6#

//R6此时已经正常与R4建立eBGP对等体关系

调试：

1．IBGP路由器从直连IBGP对等体学来的路由条目不会再传送给另外一个直连IBGP对等体。

如下图所示，如果R3不会将自己从iBGP对等体R1学习到的1.1.1.0/24网段传递给另一个iBGP对等体R4证明此结论正确。

首先我们查看R3的bgp表：

R3#show ip bgp

BGP table version is 4, local router ID is3.3.3.3

Status codes: s suppressed, d damped, hhistory, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? -incomplete

Network Next Hop Metric LocPrf Weight Path

*>i1.1.1.0/24 13.1.1.1 0 100 0 i

*> 3.3.3.0/24 0.0.0.0 0 32768 i

*>i4.4.4.0/24 34.3.3.4 0 100 0 i

* i5.5.5.0/24 45.4.4.5 0 100 0 65002 i

* i6.6.6.0/24 46.4.4.6 0 100 0 65003 i

//我们发现R3学习到了R1的lo0

再来查看R4的BGP表

R4#show ip bgp

BGP table version is 6, local router ID is 4.4.4.4

Status codes: s suppressed, d damped, h history, * valid, > best, i -internal,

r RIB-failure, SStale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*>i2.2.2.0/24 24.2.2.2 0 100 0 i

*>i3.3.3.0/24 34.3.3.3 0 100 0 i

*> 4.4.4.0/24 0.0.0.0 0 32768 i

*> 5.5.5.0/24 45.4.4.5 0 0 65002 i

*> 6.6.6.0/24 46.4.4.6 0 0 65003 i

R4#

//我们发现R4并没有学习到了R1的lo0

2．IBGP路由器会将自己从其他IBGP对等体学来的条目传给自身直连的EBGP对等体。

如果R5学习到R3的3.3.3.0/24路由条目，确定此结论正确。

首先我们查看R4的BGP表

R4#show ip bgp

BGP table version is 6, local router ID is4.4.4.4

Status codes: s suppressed, d damped, hhistory, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? -incomplete

Network Next Hop Metric LocPrf Weight Path

*>i2.2.2.0/24 24.2.2.2 0 100 0 i

*>i3.3.3.0/24 34.3.3.3 0 100 0 i

*> 4.4.4.0/24 0.0.0.0 0 32768 i

*> 5.5.5.0/24 45.4.4.5 0 0 65002 i

*> 6.6.6.0/24 46.4.4.6 0 0 65003 i

R4#

//R4学习到R3的路由

再来查看R5的BGP表

R5#show ip bgp

BGP table version is 6, local router ID is5.5.5.5

Status codes: s suppressed, d damped, hhistory, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? -incomplete

Network Next Hop Metric LocPrf Weight Path

*> 2.2.2.0/24 45.4.4.4 0 65001 i

*>3.3.3.0/24 45.4.4.4 0 65001 i

*> 4.4.4.0/24 45.4.4.4 0 0 65001 i

*> 5.5.5.0/24 0.0.0.0 0 32768 i

*> 6.6.6.0/24 45.4.4.4 0 65001 65003 i

R5#

//我们发现R5确实学习到了R3 的路由，证明上结论没有问题

3．从EBGP对等体学来的路由条目会传递给自身直连的IBGP对等体。

如果R4从eBGP对等体R5学习到5.5.5.0/24网段可以传递给iBGP对等体R3，则可证明结论正确

那么首先我们查看R4的BGP表

R4#show ip bgp

BGP table version is 6, local router ID is4.4.4.4

Status codes: s suppressed, d damped, hhistory, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? -incomplete

Network Next Hop Metric LocPrf Weight Path

*>i2.2.2.0/24 24.2.2.2 0 100 0 i

*>i3.3.3.0/24 34.3.3.3 0 100 0 i

*> 4.4.4.0/24 0.0.0.0 0 32768 i

*>5.5.5.0/24 45.4.4.5 0 0 65002 i

*> 6.6.6.0/24 46.4.4.6 0 0 65003 i

R4#

//我们发现R4学习到了5.5.5.0的路由

再来查看R3的bgp表

R3#show ip bgp

BGP table version is 4, local router ID is3.3.3.3

Status codes: s suppressed, d damped, hhistory, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*>i1.1.1.0/24 13.1.1.1 0 100 0 i

*> 3.3.3.0/24 0.0.0.0 0 32768 i

*>i4.4.4.0/24 34.3.3.4 0 100 0 i

*i5.5.5.0/24 45.4.4.5 0 100 0 65002 i

* i6.6.6.0/24 46.4.4.6 0 100 0 65003 i

R3#

//我们发现R3也学习到了5.5.5.0/24，说明R4会传递R5的5.5.5.0/24网段

4．从EBGP对等体学来的路由条目会传递给其他EBGP对等体。

我们可以在R5和R6上测试，观察R4从eBGP对等体R6学习到的6.6.6.0/24是否会传递给eBGP对等体R5

首先，我们查看R4的bgp表

R4#show ip bgp

BGP table version is 6, local router ID is 4.4.4.4

Status codes: s suppressed, d damped, h history, * valid, >best, i - internal,

rRIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*>i2.2.2.0/24 24.2.2.2 0 100 0 i

*>i3.3.3.0/24 34.3.3.3 0 100 0 i

*> 4.4.4.0/24 0.0.0.0 0 32768 i

*> 5.5.5.0/24 45.4.4.5 0 0 65002 i

*> 6.6.6.0/24 46.4.4.6 0 0 65003 i

R4#

//我们发现R4学习到了R6的6.6.6.0/24

再来查看R5的bgp表

R5#showip bgp

BGPtable version is 6, local router ID is 5.5.5.5

Statuscodes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origincodes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*>2.2.2.0/24 45.4.4.4 0 65001 i

*>3.3.3.0/24 45.4.4.4 0 65001 i

*>4.4.4.0/24 45.4.4.4 0 0 65001 i

*>5.5.5.0/24 0.0.0.0 0 32768 i

*> 6.6.6.0/24 45.4.4.4 0 65001 65003 i

//此时R5也同样学习到R6的6.6.6.0/24网络，证明结论没有问题

5．从IBGP对等体学来的路由条目再传送给EBGP对等体，下一跳会改成自己的出口。

我们测试R2的2.2.2.0/24网段在传递给iBGP对等体R4后，由R4在传递给直连的eBGP对等体，下一跳是否修改？

首先，我们查看R4的BGP表

R4#showip bgp

BGPtable version is 6, local router ID is 4.4.4.4

Statuscodes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origincodes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*>i2.2.2.0/24 24.2.2.2 0 100 0 i

*>i3.3.3.0/24 34.3.3.3 0 100 0 i

*>4.4.4.0/24 0.0.0.0 0 32768 i

*>5.5.5.0/24 45.4.4.5 0 0 65002 i

*>6.6.6.0/24 46.4.4.6 0 0 65003 i

//我们发现此时R4从iBGP对等体R2学习到的2.2.2.0/24网段的下一跳为R2的出口IP地址24.2.2.2

再来查看R5的BGP表

R5#showip bgp

BGPtable version is 6, local router ID is 5.5.5.5

Statuscodes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origincodes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 2.2.2.0/24 45.4.4.4 0 65001 i

*>3.3.3.0/24 45.4.4.4 0 65001 i

*>4.4.4.0/24 45.4.4.4 0 0 65001 i

*>5.5.5.0/24 0.0.0.0 0 32768 i

*>6.6.6.0/24 45.4.4.4 0 65001 65003 i

R5#

//我们发现R5学习到的2.2.2.0/24的下一跳已经更改为R4 的出口45.4.4.4

6．从EBGP对等体学来的路由条目再传送给IBGP对等体，下一跳不会更改为自己的出口。

这里测试R4从eBGP对等体R5学习到的5.5.5.0/24在传递给iBGP对等体R2，下一跳是否更改

首先，我们查看R4的BGP表

R4#show ip bgp

BGP table version is 6, localrouter ID is 4.4.4.4

Status codes: s suppressed, ddamped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e -EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*>i2.2.2.0/24 24.2.2.2 0 100 0 i

*>i3.3.3.0/24 34.3.3.3 0 100 0 i

*> 4.4.4.0/24 0.0.0.0 0 32768 i

*> 5.5.5.0/24 45.4.4.5 0 0 65002 i

*> 6.6.6.0/24 46.4.4.6 0 0 65003 i

R4#

//我们发现R4学习到的5.5.5.0/24网段的下一跳IP地址是45.4.4.5

我们再来查看R2的BGP表

R2#show ip bgp

BGP table version is 4, localrouter ID is 2.2.2.2

Status codes: s suppressed, ddamped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e -EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*>i1.1.1.0/24 12.1.1.1 0 100 0 i

*> 2.2.2.0/24 0.0.0.0 0 32768 i

*>i4.4.4.0/24 24.2.2.4 0 100 0 i

* i5.5.5.0/24 45.4.4.5 0 100 0 65002 i

* i6.6.6.0/24 46.4.4.6 0 100 0 65003 i

R2#

//我们得出R2学习到的5.5.5.0/24网段，下一跳IP地址依然是为45.4.4.5，没有改变。

并且在R2的BGP中没有出现大于号（即最后路径的标记），那么R2是不会将它装入路由表的，我们查看R2的路由表

R2#show ip route bgp

1.0.0.0/24 is subnetted, 1 subnets

B 1.1.1.0 [200/0] via 12.1.1.1, 00:20:10

4.0.0.0/24 is subnetted, 1 subnets

B 4.4.4.0 [200/0] via 24.2.2.4, 00:18:18

R2#

//我们发现R2并没有将5.5.5.0/24网段装入路由表，原因是由于在R2的BGP中对应的下一跳地址45.4.4.5所在的网段45.4.4.0/24网段，对于R2 而言不可达造成。我们再来查看R2的IGP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 - OSPFexternal type 2

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

ia - IS-IS inter area, * - candidatedefault, U - per-user static route

o - ODR, P - periodic downloaded staticroute

Gateway of last resort is notset

34.0.0.0/24 is subnetted, 1 subnets

O 34.3.3.0 [110/128] via 24.2.2.4, 00:19:55,Serial1/0

1.0.0.0/24 is subnetted, 1 subnets

B 1.1.1.0 [200/0] via 12.1.1.1, 00:20:02

2.0.0.0/24 is subnetted, 1 subnets

C 2.2.2.0 is directly connected, Loopback0

4.0.0.0/24 is subnetted, 1 subnets

B 4.4.4.0 [200/0] via 24.2.2.4, 00:18:10

20.0.0.0/24 is subnetted, 1 subnets

C 20.20.20.0 is directly connected,Loopback10

24.0.0.0/24 is subnetted, 1 subnets

C 24.2.2.0 is directly connected,Serial1/0

40.0.0.0/24 is subnetted, 1 subnets

O 40.40.40.0 [110/65] via 24.2.2.4, 00:19:55,Serial1/0

10.0.0.0/24 is subnetted, 1 subnets

O 10.10.10.0 [110/65] via 12.1.1.1,00:19:55, Serial1/1

12.0.0.0/24 is subnetted, 1 subnets

C 12.1.1.0 is directly connected,Serial1/1

13.0.0.0/24 is subnetted, 1 subnets

O 13.1.1.0 [110/128] via 12.1.1.1,00:19:55, Serial1/1

30.0.0.0/24 is subnetted, 1 subnets

O 30.30.30.0 [110/129] via 12.1.1.1,00:19:55, Serial1/1

[110/129] via 24.2.2.4,00:19:55, Serial1/0

R2#

//我们发现R2确实没有对应的45.4.4.0/24网段的路由在IGP路由表中。

补充：如果想让R2将学习到的5.5.5.0/24，装入对应的路由表中，我们必须满足下一跳可达，这里可以用静态路由、重发布IGP、next-hop-self等完成可达。

7．从EBGP对等体学来的路由条目，再传送给EBGP路由器，下一跳更改为自己的出口。

这里我们测试R5从eBGP对等体R4学习到R6的6.6.6.0/24网段，下一跳是否会更改

首先，我们查看R4 的BGP表

R4#show ip bgp

BGP table version is 6, localrouter ID is 4.4.4.4

Status codes: s suppressed, ddamped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e -EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*>i2.2.2.0/24 24.2.2.2 0 100 0 i

*>i3.3.3.0/24 34.3.3.3 0 100 0 i

*> 4.4.4.0/24 0.0.0.0 0 32768 i

*> 5.5.5.0/24 45.4.4.5 0 0 65002 i

*> 6.6.6.0/24 46.4.4.6 0 0 65003 i

R4#

//我们得出R4学习到R6的6.6.6.0/24网段，下一跳为R6的出口IP地址46.4.4.6

然后我们查看R5的BGP表

R5#show ip bgp

BGP table version is 6, localrouter ID is 5.5.5.5

Status codes: s suppressed, ddamped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e -EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 2.2.2.0/24 45.4.4.4 0 65001 i

*> 3.3.3.0/24 45.4.4.4 0 65001 i

*> 4.4.4.0/24 45.4.4.4 0 0 65001 i

*> 5.5.5.0/24 0.0.0.0 0 32768 i

*> 6.6.6.0/24 45.4.4.4 0 65001 65003 i

R5#

//我们发现R5学习到的6.6.6.0/24网段，下一跳变更为R4 的出口IP地址45.4.4.4

补充：此时我们发现整个网络没有收敛，这是由于BGP路由传递原则造成，这里可以采用Full-Mesh、RR等解决方案来完成收敛。

上一篇：思科系列课程---CCNP考试大纲

下一篇：BGP的路由反射器

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