BGP路由策略实验（H3C）

weyr · 发表于 2013-6-3 08:36:21

一．实验拓扑图

二、实验要求

1.互联链路配置及测试

2.AS65001和AS65002的IGP配置及测试(修改以太网接口网络类型为P2P，修改R2、R3间OSPF链路开销为10，请不要将AS65001的业务网段发布进IGP)。

3.按图示建立BGP邻居关系，并查看BGP邻居表(请不要忘记针对IBGP邻居修改更新源和下一跳)。

4.在R1、R2、R3、R4上用BGP发布各自AS的业务网段路由（Loop1）

5.查看各台路由器的BGP路由表和IP转发表，查看是否有去往其他AS业务网段的路由。请分析R6的BGP路由表中的最优BGP路由是如何选择的？

6.测试各业务网段间的连通性。

7.在合适的位置上通过修改Local-Pre值实现AS65002的业务网段去往10.30.1.1的主路径走R1-R2，去往10.40.4.1的主路径走R3-R4，使用Tracert命令测试。

8. 还原第7步的配置后，在合适的位置上通过修改MED值实现AS65002的业务网段去往10.30.1.1的主路径走R1-R2，去往10.40.4.1的主路径走R3-R4使用Tracert命令测试。

三、实验过程

[R1]bgp 65001

[R1-bgp]peer 10.0.1.6 as-num 65002

[R1-bgp]peer 4.4.4.4 as-num 65002

[R1-bgp]peer 4.4.4.4 connect-int lo0

[R1-bgp]peer 4.4.4.4 next-hop-lo

[R4]bgp 65001

[R4-bgp]peer 10.0.1.10 as-num 65002

[R4-bgp]peer 1.1.1.1 as-num 65001

[R4-bgp]peer 1.1.1.1 connect-int lo0

[R4-bgp]peer 1.1.1.1 next-hop-lo

[R2]bgp 65002

[R2-bgp]peer 10.0.1.5 as-num 65001

[R2-bgp]group rr internal

[R2-bgp]peer rr next-hop-lo

[R2-bgp]peer rr connect-int lo0

[R2-bgp]peer 3.3.3.3 group rr

[R2-bgp]peer 5.5.5.5 group rr

[R2-bgp]peer 6.6.6.6 group rr

[R3]bgp 65002

[R3-bgp]peer 10.0.1.9 as-num 65001

[R3-bgp]group nn internal

[R3-bgp]peer nn next-hop-lo

[R3-bgp]peer nn connect-int lo0

[R3-bgp]peer 2.2.2.2 group nn

[R3-bgp]peer 5.5.5.5 group nn

[R3-bgp]peer 6.6.6.6 group nn

[R5]bgp 65002

[R5-bgp]group mm internal

[R5-bgp]peer mm next

[R5-bgp]peer mm next-hop-local

[R5-bgp]peer mm con

[R5-bgp]peer mm connect-interface lo0

[R5-bgp]peer 2.2.2.2 group mm

[R5-bgp]peer 3.3.3.3 group mm

[R5-bgp]peer 6.6.6.6 group mm

[R6]bgp 65002

[R6-bgp]group ii internal

[R6-bgp]peer ii ne

[R6-bgp]peer ii next-hop-local

[R6-bgp]peer ii con

[R6-bgp]peer ii connect-interface lo0

[R6-bgp]peer 2.2.2.2 group ii

[R6-bgp]peer 5.5.5.5 group ii

[R6-bgp]peer 3.3.3.3 group ii

[R6-bgp]

[R2-bgp]net 10.10.5.1 32

[R2-bgp]net 10.10.6.1 32

[R2-bgp]

[R3-bgp]net 10.10.5.1 32

[R3-bgp]net 10.10.6.1 32

[R3-bgp]

[R1-bgp]net 10.30.1.1 32

[R4-bgp]net 10.40.4.1 32

[R2]bgp 65002

[R2-bgp]peer 10.0.1.5 route-po lp import

[R2-bgp]q

[R2]route-po lp permit node 10

New Sequence of this List

[R2-route-policy]if-m acl 2003

[R2-route-policy]apply local-pre 300

[R2-route-policy]qui

[R2]acl num 2003

[R2-acl-basic-2003]rule permit source 10.30.1.1 0.0.0.0

[R2-acl-basic-2003]qui

问题：

1.BGP发言者network的路由以及自己使用的路由才会发布到对等体

2.BGP路由表里可用与最优是什么意思？

最优的一定是可用的，可用的不一定是最优的。

在R3上（BGP里）network3.3.3.3 32 之后

[R4]dis ip rout

Routing Tables: Public

Destinations : 8 Routes : 8

Destination/Mask Proto Pre Cost NextHop Interface

4.4.4.4/32 Direct 0 0 127.0.0.1 InLoop0

10.0.1.0/30 Direct 0 0 10.0.1.2 Eth0/1/0

10.0.1.2/32 Direct 0 0 127.0.0.1 InLoop0

10.0.1.8/30 Direct 0 0 10.0.1.9 Eth0/1/1

10.0.1.9/32 Direct 0 0 127.0.0.1 InLoop0

10.40.4.1/32 Direct 0 0 127.0.0.1 InLoop0

127.0.0.0/8 Direct 0 0 127.0.0.1 InLoop0

127.0.0.1/32 Direct 0 0 127.0.0.1 InLoop0

[R4] dis bgp rout

Total Number of Routes: 2

BGP Local router ID is 10.40.4.1

Status codes: * - valid, > - best, d - damped,

h - history, i - internal, s - suppressed, S - Stale

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

Network NextHop MED LocPrf PrefVal Path/Ogn

*> 3.3.3.3/32 10.0.1.10 0 0 65002i

*> 10.40.4.1/32 0.0.0.0 0 0 i

<R5> dis bgp rout

Total Number of Routes: 3

BGP Local router ID is 10.10.5.1

Status codes: * - valid, > - best, d - damped,

h - history, i - internal, s - suppressed, S - Stale

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

Network NextHop MED LocPrf PrefVal Path/Ogn

i 3.3.3.3/32 3.3.3.3 0 100 0 i

*>i 10.30.1.1/32 2.2.2.2 0 100 0 65001i

*>i 10.40.4.1/32 3.3.3.3 0 100 0 65001i

<R5>dis ip rout

Routing Tables: Public

Destinations : 17 Routes : 20

Destination/Mask Proto Pre Cost NextHop Interface

2.2.2.2/32 OSPF 10 10 10.0.1.17 Eth0/1/0

3.3.3.3/32 OSPF 10 20 10.0.1.17 Eth0/1/0

OSPF 10 20 10.0.1.26 Eth0/1/2

5.5.5.5/32 Direct 0 0 127.0.0.1 InLoop0

6.6.6.6/32 OSPF 10 10 10.0.1.26 Eth0/1/2

10.0.1.4/30 OSPF 10 20 10.0.1.17 Eth0/1/0

10.0.1.8/30 OSPF 10 30 10.0.1.17 Eth0/1/0

OSPF 10 30 10.0.1.26 Eth0/1/2

10.0.1.12/30 OSPF 10 20 10.0.1.17 Eth0/1/0

10.0.1.16/30 Direct 0 0 10.0.1.18 Eth0/1/0

10.0.1.18/32 Direct 0 0 127.0.0.1 InLoop0

10.0.1.20/30 OSPF 10 20 10.0.1.26 Eth0/1/2

10.0.1.24/30 Direct 0 0 10.0.1.25 Eth0/1/2

10.0.1.25/32 Direct 0 0 127.0.0.1 InLoop0

10.10.5.1/32 Direct 0 0 127.0.0.1 InLoop0

10.30.1.1/32 BGP 255 0 2.2.2.2 Eth0/1/0

10.40.4.1/32 BGP 255 0 3.3.3.3 Eth0/1/0

BGP 255 0 3.3.3.3 Eth0/1/2

127.0.0.0/8 Direct 0 0 127.0.0.1 InLoop0

127.0.0.1/32 Direct 0 0 127.0.0.1 InLoop0

[R3]dis ip rout

Routing Tables: Public

Destinations : 18 Routes : 19

Destination/Mask Proto Pre Cost NextHop Interface

2.2.2.2/32 OSPF 10 10 10.0.1.13 S0/2/0

3.3.3.3/32 Direct 0 0 127.0.0.1 InLoop0

5.5.5.5/32 OSPF 10 20 10.0.1.13 S0/2/0

OSPF 10 20 10.0.1.22 Eth0/1/1

6.6.6.6/32 OSPF 10 10 10.0.1.22 Eth0/1/1

10.0.1.4/30 OSPF 10 20 10.0.1.13 S0/2/0

10.0.1.8/30 Direct 0 0 10.0.1.10 Eth0/1/3

10.0.1.10/32 Direct 0 0 127.0.0.1 InLoop0

10.0.1.12/30 Direct 0 0 10.0.1.14 S0/2/0

10.0.1.13/32 Direct 0 0 10.0.1.13 S0/2/0

10.0.1.14/32 Direct 0 0 127.0.0.1 InLoop0

10.0.1.16/30 OSPF 10 20 10.0.1.13 S0/2/0

10.0.1.20/30 Direct 0 0 10.0.1.21 Eth0/1/1

10.0.1.21/32 Direct 0 0 127.0.0.1 InLoop0

10.0.1.24/30 OSPF 10 20 10.0.1.22 Eth0/1/1

10.30.1.1/32 BGP 255 0 2.2.2.2 S0/2/0

10.40.4.1/32 BGP 255 0 10.0.1.9 Eth0/1/3

127.0.0.0/8 Direct 0 0 127.0.0.1 InLoop0

127.0.0.1/32 Direct 0 0 127.0.0.1 InLoop0

[R3]dis bgp rout

Total Number of Routes: 3

BGP Local router ID is 3.3.3.3

Status codes: * - valid, > - best, d - damped,

h - history, i - internal, s - suppressed, S - Stale

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

Network NextHop MED LocPrf PrefVal Path/Ogn

*> 3.3.3.3/32 0.0.0.0 0 0 i

*>i 10.30.1.1/32 2.2.2.2 0 100 0 65001i

*> 10.40.4.1/32 10.0.1.9 0 0 65001i

3.R1和R4互相收不到路由。

<R1>dis ip rout

Routing Tables: Public

Destinations : 9 Routes : 9

Destination/Mask Proto Pre Cost NextHop Interface

1.1.1.1/32 Direct 0 0 127.0.0.1 InLoop0

10.0.1.0/30 Direct 0 0 10.0.1.1 Eth0/1/2

10.0.1.1/32 Direct 0 0 127.0.0.1 InLoop0

10.0.1.4/30 Direct 0 0 10.0.1.5 Eth0/1/0

10.0.1.5/32 Direct 0 0 127.0.0.1 InLoop0

10.10.5.1/32 BGP 255 10 10.0.1.6 Eth0/1/0

10.30.1.1/32 Direct 0 0 127.0.0.1 InLoop0

127.0.0.0/8 Direct 0 0 127.0.0.1 InLoop0

127.0.0.1/32 Direct 0 0 127.0.0.1 InLoop0

<R4>dis ip rout

Routing Tables: Public

Destinations : 10 Routes : 10

Destination/Mask Proto Pre Cost NextHop Interface

3.3.3.3/32 BGP 255 0 10.0.1.10 Eth0/1/1

4.4.4.4/32 Direct 0 0 127.0.0.1 InLoop0

10.0.1.0/30 Direct 0 0 10.0.1.2 Eth0/1/0

10.0.1.2/32 Direct 0 0 127.0.0.1 InLoop0

10.0.1.8/30 Direct 0 0 10.0.1.9 Eth0/1/1

10.0.1.9/32 Direct 0 0 127.0.0.1 InLoop0

10.10.5.1/32 BGP 255 20 10.0.1.10 Eth0/1/1

10.40.4.1/32 Direct 0 0 127.0.0.1 InLoop0

127.0.0.0/8 Direct 0 0 127.0.0.1 InLoop0

127.0.0.1/32 Direct 0 0 127.0.0.1 InLoop0

查看邻居是否建立

<R1> dis bgp peer

BGP local router ID : 10.30.1.1

Local AS number : 65001

Total number of peers : 2 Peers in established state : 1

Peer V AS MsgRcvd MsgSent OutQ PrefRcv Up/Down State

4.4.4.4 4 65002 0 0 0 0 00:45:19 Active

10.0.1.6 4 65002 49 61 0 1 00:44:48 Established

<R4> dis bgp peer

BGP local router ID : 10.40.4.1

Local AS number : 65001

Total number of peers : 2 Peers in established state : 1

Peer V AS MsgRcvd MsgSent OutQ PrefRcv Up/Down State

1.1.1.1 4 65001 0 0 0 0 01:02:43 Active

10.0.1.10 4 65002 84 84 0 2 01:02:11 Established

邻居未建立，停在了Active状态。为什么。

排错：BGP邻居通过对比open消息建立连接关系，并进行了参数协商。内容包括：BGP版本号，自己所属的AS号，路由器ID，hold time值、认证信息。

1）于是首先发现R1配对等体时AS号错了。改正之后还是不行。

2）后来发现建邻居用的是loopback接口，TCP三次握手需要路由才能到，由于没有到对方loopback口的路由，所以无法建立TCP连接，所以建立不了邻居。

配了到各自的静态的路由之后，可以建立邻居。

问题，不配静态路由，R1，R4能否通过跨越AS 65002建邻居。前提在BGP里network了loopback网段。

[R1]undo ip rout 10.40.4.1 255.255.255.255 10.0.1.2

[R1]dis bgp peer

BGP local router ID : 10.30.1.1

Local AS number : 65001

Total number of peers : 2 Peers in established state : 2

Peer V AS MsgRcvd MsgSent OutQ PrefRcv Up/Down State

10.0.1.6 4 65002 246 315 0 1 03:58:23 Established

10.40.4.1 4 65001 25 19 0 2 00:15:15 Established

[R1]

（BGP连接隔了一两分钟才断开，可以通过重启进程）

%Aug 31 15:29:07:438 2012 R1 RM/3/RMLOG:

BGP.: 10.40.4.1 State is changed from ESTABLISHED to IDLE.

[R1]

[R1]dis bgp peer

BGP local router ID : 10.30.1.1

Local AS number : 65001

Total number of peers : 2 Peers in established state : 1

Peer V AS MsgRcvd MsgSent OutQ PrefRcv Up/Down State

10.0.1.6 4 65002 250 320 0 1 04:02:01 Established

10.40.4.1 4 65001 0 0 0 0 00:01:51 Active

4.R4 ping 10.10.5.1 要带源ping，并且源是在BGP里发布了的10.40.4.1 ，否则不通，因为要保证对端有回来的路由。

<R4>trace -a 10.40.4.1 10.10.5.1

traceroute to 10.10.5.1(10.10.5.1) 30 hops max,40 bytes packet, press CTRL_C to break

1 10.0.1.1 4294967291 ms 20 ms <1 ms

2 10.0.1.6 10 ms 20 ms 20 ms

3 10.10.5.1 30 ms 25 ms 5 ms

<R5> trace -a 10.10.5.1 10.40.4.1

traceroute to 10.40.4.1(10.40.4.1) 30 hops max,40 bytes packet, press CTRL_C to break

1 10.0.1.26 30 ms 10.0.1.17 4 ms 10.0.1.26 15 ms

2 10.0.1.14 15 ms 10.0.1.21 25 ms 10.0.1.14 21 ms

3 10.40.4.1 14 ms 10 ms 35 ms

5.修改路由信息属性来控制数据流方向

修改local-pre值，实现AS65002的业务网段去往10.30.1.1的主路径走R1-R2，去往10.40.4.1的主路径走R3-R4，使用Tracert命令测试。

1） local-pre该配在哪里？根据BGP的路由选路规则，R2，R3，R5去往10.30.1.1的路径都是R1-R2

现在只有

[R2]acl num 2003

[R2-acl-basic-2003]rule 1 permit source 10.30.1.1 0.0.0.0

[R2-acl-basic-2003]q

[R2]route-policy R1-R2 permit node 10

New Sequence of this List

[R2-route-policy]if-match acl 2003

[R2-route-policy]apply local-pre 200

[R2-route-policy]q

[R2]bgp 65002

[R2-bgp]peer 10.0.1.5 route-policy R1-R2 import

[R3]acl num 2003

[R3-acl-basic-2003]rule 1 permit source 10.40.4.1 0.0.0.0

[R3-acl-basic-2003]q

[R3]route-policy R3-R4 permit node 10

New Sequence of this List

[R3-route-policy]if-match acl 2003

[R3-route-policy]apply ?

as-path Prepend the as-path string to the AS path

comm-list Set BGP community list (for deletion)

community BGP community attribute

cost Set cost of the matched route

cost-type Type of metric for destination routing protocol

extcommunity BGP extended community attribute

ip-address IP information

ipv6 IPv6 Information

isis IS-IS routing protocol defined by ISO

local-preference BGP local preference

mpls-label Match MPLS label

origin BGP origin code

preference Give the Preference (Route Preference)

preferred-value BGP Preferred-value (weight) for routing table

tag Set tag of route

[R3-route-policy]apply local-pre 300

[R3-route-policy]q

[R3]bgp 65002

[R3-bgp]peer 10.0.1.9 route-policy R3-R4 ?

export Specify export policy

import Specify import policy

[R3-bgp]peer 10.0.1.9 route-policy R3-R4 import

修改后的效果

<R6>dis bgp rout

Total Number of Routes: 7

BGP Local router ID is 6.6.6.6

Status codes: * - valid, > - best, d - damped,

h - history, i - internal, s - suppressed, S - Stale

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

Network NextHop MED LocPrf PrefVal Path/Ogn

i 3.3.3.3/32 3.3.3.3 0 100 0 i

* i 10.10.5.1/32 2.2.2.2 10 100 0 i

* i 3.3.3.3 20 100 0 i

* i 10.10.6.1/32 3.3.3.3 10 100 0 i

* i 2.2.2.2 20 100 0 i

*>i 10.30.1.1/32 2.2.2.2 0 200 0 65001i

*>i 10.40.4.1/32 3.3.3.3 0 300 0 65001i

6.<R2> dis bgp rout

Total Number of Routes: 8

BGP Local router ID is 2.2.2.2

Status codes: * - valid, > - best, d - damped,

h - history, i - internal, s - suppressed, S - Stale

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

Network NextHop MED LocPrf PrefVal Path/Ogn

i 3.3.3.3/32 3.3.3.3 0 100 0 i

*> 10.10.5.1/32 0.0.0.0 10 0 i

* i 3.3.3.3 20 100 0 i

*> 10.10.6.1/32 0.0.0.0 20 0 i

*> 0.0.0.0 20 0 i

* i 3.3.3.3 10 100 0 i

*> 10.30.1.1/32 10.0.1.5 0 200 0 65001i

*>i 10.40.4.1/32 3.3.3.3 0 100 0 65001i

这里的i是指从本自治系统收到的。

疑问：为什么R2收不到来自R1发来的10.40.4.1这条路由？

R3也收不到来自R4发来的10.30.1.1这条路由？

原因是：原来配错了，导致R1与R4邻居建立不起来。

[R3]dis bgp rout

Total Number of Routes: 10

BGP Local router ID is 3.3.3.3

Status codes: * - valid, > - best, d - damped,

h - history, i - internal, s - suppressed, S - Stale

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

Network NextHop MED LocPrf PrefVal Path/Ogn

*> 3.3.3.3/32 0.0.0.0 0 0 i

*> 10.10.5.1/32 0.0.0.0 20 0 i

*> 0.0.0.0 20 0 i

* i 2.2.2.2 10 100 0 i

*> 10.10.6.1/32 0.0.0.0 10 0 i

* i 2.2.2.2 20 100 0 i

*> 10.30.1.1/32 10.0.1.9 0 65001i

* i 2.2.2.2 0 100 0 65001i

*> 10.40.4.1/32 10.0.1.9 0 0 65001i

* i 2.2.2.2 100 0 65001i

<R2>dis bgp rout

Total Number of Routes: 10

BGP Local router ID is 2.2.2.2

Status codes: * - valid, > - best, d - damped,

h - history, i - internal, s - suppressed, S - Stale

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

Network NextHop MED LocPrf PrefVal Path/Ogn

i 3.3.3.3/32 3.3.3.3 0 100 0 i

*> 10.10.5.1/32 0.0.0.0 10 0 i

* i 3.3.3.3 20 100 0 i

*> 10.10.6.1/32 0.0.0.0 20 0 i

*> 0.0.0.0 20 0 i

* i 3.3.3.3 10 100 0 i

*> 10.30.1.1/32 10.0.1.5 0 0 65001i

* i 3.3.3.3 100 0 65001i

*> 10.40.4.1/32 10.0.1.5 0 65001i

* i 3.3.3.3 0 100 0 65001i

2）配置MED值

[R2]acl num 2004

[R2-acl-basic-2004]rule 1 permit source

%Aug 31 22:04:15:00 2012 R2 RM/3/RMLOG:

BGP.: 6.6.6.6 State is changed from OPENCONFIRM to ESTABLISHED.

10.40.4.1 0.0.0.0

[R2-acl-basic-2004]q

[R2]

%Aug 31 22:04:35:968 2012 R2 RM/3/RMLOG:

BGP.: 5.5.5.5 State is changed from OPENCONFIRM to ESTABLISHED.

[R2]route-policy R3-R4 permit node 10

New Sequence of this List

[R2-route-policy]if-match acl 2004

[R2-route-policy]apply cost 100

[R2]bgp 65002

[R2-bgp]peer 10.0.1.5 route-policy R3-R4 import

[R3]acl num 2004

[R3-acl-basic-2004]rule 1 permit source 10.30.1.1 0.0.0.0

[R3-acl-basic-2004]q

[R3]

[R3]route-policy R3-R4 permit node 10

New Sequence of this List

[R3-route-policy]if-match acl 2004

[R3-route-policy]apply cost 100

[R3]bgp 65002

[R3-bgp]peer 10.0.1.5 route-policy R1-R2 import

模拟器问题，敲下apply cost 100，自动关闭了路由器的模拟窗口？

只在各自上配一条就行了，相对提高值！

四、实验总结

小结： 1.有些路由会显示本地优先级，有些不会，是因为没有发过来？

2.BGP发言者只将自己使用的路由（BGP路由表里的路由）发布给对等体

3.只有在自己全局路由表里存在有的路由，才能通告BGP network 出去！

4.H3C MSR路由器默认关闭了同步，R3上从R5上收到了10.10.5.1的路由，会直接发给自己EBGP R4，由于R3所在区域配置了全互联，所以不会产生路由“黑洞”。

5.全局路由表里显示的直连网段下一跳是自己的出接口

6.EBGP之间建邻居为什么用物理接口？IBGP之间建邻居为什么用loopback0接口？

7.断开R1、R4的连接关系、10.40.4.1 这条路由不会发给R1，因为防环机制，AS号重复了。

YY-LIN · 发表于 2013-6-3 08:53:49

所有的男人生来平等，结婚的除外。

心海恋歌 · 发表于 2013-6-3 10:46:30

只要不下流，我们就是主流!

ukula · 发表于 2013-6-3 14:52:15

我在马路边丢了一分钱

kaiser_cn · 发表于 2013-6-3 16:10:03

修养的艺术,其实就是说谎的艺术。

link · 发表于 2013-6-3 20:15:20

沒有激情的亲吻，哪來床上的翻滾？

jinquan26 · 发表于 2013-6-3 23:32:39

走，MM，咱们化蝶去……

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