CCNP-31 BGP 1

2007-12-04 21:41:39

　标签：网络 cisco CCNP BGP　　　[推送到技术圈]

CCNP-31 BGP 1

实验拓扑：

实验要求：R1属于AS 65500中的一台路由器，R2-4属于AS 65000中的路由器，在AS 65000中使用的事OSPF路由协议，R1与R2配置成为EBGP PEER，R2与R4之间配置成为IBGP PEER。

试验目的：掌握基本的EBGP和IBGP的配置和传递路由需要的条件，能够使用show和debug来解决简单的问题。

试验配置：

R1：

R1(config)#int f0/0

R1(config-if)#ip add 10.1.1.1 255.255.255.0

R1(config-if)#no shu

R1(config-if)#exit

R1(config)#int f1/0

R1(config-if)#exit

R1(config)#int f1/0

R1(config-if)#ip add 172.16.1.1 255.255.255.0

R1(config-if)#no shu

R1(config-if)#no keepalive

R1(config-if)#exit

R2：

R2(config)#int f0/0

R2(config-if)#ip add 10.1.1.2 255.255.255.0

R2(config-if)#no shu

R2(config-if)#exit

R2(config)#int f1/0

R2(config-if)#ip add 192.1.1.1 255.255.255.0

R2(config-if)#no shu

R2(config-if)#exit

R2(config)#int loop0

R2(config-if)#ip add 2.2.2.2 255.255.255.0

R2(config-if)#exit

R2(config)#int loop1

R2(config-if)#ip add 172.16.2.1 255.255.255.0

R2(config-if)#no shu

R2(config-if)#exit

R2(config)#router ospf 100

R2(config-router)#router-id 2.2.2.2

R2(config-router)#network 0.0.0.0 0.0.0.0 a 0

R2(config-router)#exit

R3：

R3(config)#int f1/0

R3(config-if)#ip add 192.1.1.2 255.255.255.0

R3(config-if)#no shu

R3(config-if)#exit

R3(config)#int f0/0

R3(config-if)#ip add 193.1.1.1 255.255.255.0

R3(config-if)#no shu

R3(config-if)#exit

R3(config)#int loop0

R3(config-if)#ip add 3.3.3.3 255.255.255.0

R3(config-if)#exit

R3(config)#router ospf 100

R3(config-router)#router-id 3.3.3.3

R3(config-router)#network 0.0.0.0 0.0.0.0 a 0

R3(config-router)#exit

R4：

R4(config)#int f0/0

R4(config-if)#ip add 193.1.1.2 255.255.255.0

R4(config-if)#no shu

R4(config-if)#exit

R4(config)#int f1/0

R4(config-if)#ip add 172.16.3.1 255.255.255.0

R4(config-if)#no shu

R4(config-if)#no keepalive

R4(config-if)#exit

R4(config)#int loop0

R4(config-if)#ip add 4.4.4.4 255.255.255.0

R4(config-if)#exit

R4(config)#router ospf 100

R4(config-router)#router-id 4.4.4.4

R4(config-router)#network 0.0.0.0 0.0.0.0 a 0

R4(config-router)#exit

基本的链路层和OSPF配置完成了，上面用红色标记的部分是因为那个接口没有连接任何设备，我们用它来模拟内部网络，如果与接口没有活动的连接，那么接口就会down掉，使用no keepalive命令来取消检测活动连接，使之一直保持在UP状态。

下面我们开始BGP的配置，如下：

R1(config)#int loop0

R1(config-if)#ip add 1.1.1.1 255.255.255.0//loopback接口和OSPF中的作用一样，用作router-id

R1(config-if)#exit

R1(config)#router bgp 65500 //65500为AS号

R1(config-router)#neighbor 10.1.1.2 remote-as 65000 //指定邻居

R1(config-router)#network 172.16.1.0 mask 255.255.255.0 //宣告网段

R2(config)#router bgp 65000

R2(config-router)#neighbor 10.1.1.1 remote-as 65500

R2(config-router)#neighbor 4.4.4.4 remote-as 65000

R2(config-router)#neighbor 4.4.4.4 update-source loop0

R2(config-router)#network 192.1.1.0

R2(config-router)#network 172.16.2.0 mask 255.255.255.0

R4(config)#router bgp 65000

R4(config-router)#neighbor 2.2.2.2 remote-as 65000

R4(config-router)#neighbor 2.2.2.2 update-source loopback 0

R4(config-router)#network 172.16.3.0 mask 255.255.255.0

R4(config-router)#network 193.1.1.0

R4(config-router)#exit

BGP的配置和其他路由协议差不多，也需要在全局模式下使用router bgp xxx命令，只不过后面的数字表示的是AS号，BGP的邻居需要管理员人工指定，并且要表明邻居所在的AS，在EBGP PEER情况下，neighbor后面的ip地址一般为直连的对端接口的IP地址，这是因为BGP有一个一跳的属性限制，可以修改，不过不建议这样做，不过在IBGP PEER的配置中，neighbor后面的ip地址的要求就没有这么严格了，只要可达的IP地址都可以，在这里我们一般使用LOOPBACK接口的IP地址作为更新源，因为loopback接口有一个永远不会down的特性，并且在多条路经的时候，用loopback地址作为更新源地址可以实现冗余（BGP不能实现负载均衡，他只选择最优的路径写入路由表！），update-source loopback 0指明更新源为loopback口，这条命令需要在使用loopback接口作为更新源的对等体路由器都要配置！

最后使用network命令宣告需要发布的路由，这里BGPv4支持VLSM与CIDR，所以BGP在更新一条路有的时候需要写出掩码，默认的是主网络的掩码，可以使用mask选项来配置掩码。

BGP和EIGRP,OSPF,ISIS一样都有三张表，邻居表，BGP路由表和IP路由表，下面我们来看看BGP的邻居表：

R2#show ip bgp neighbors

BGP neighbor is 4.4.4.4, remote AS 65000, internal link //IBGP邻居

BGP version 4, remote router ID 4.4.4.4 //BGP版本，邻居路由ID

BGP state = Established, up for 00:03:56 //邻居状态Established

Last read 00:00:55, last write 00:00:55, hold time is 180, keepalive interval is 60 seconds

Neighbor capabilities:

Route refresh: advertised and received(old & new)

Address family IPv4 Unicast: advertised and received

Message statistics:

InQ depth is 0

OutQ depth is 0

Sent Rcvd

Opens: 1 1

Notifications: 0 0

Updates: 2 2

Keepalives: 6 6

Route Refresh: 0 0

Total: 9 9

Default minimum time between advertisement runs is 0 seconds

For address family: IPv4 Unicast

BGP table version 8, neighbor version 8/0

Output queue size : 0

Index 2, Offset 0, Mask 0x4

2 update-group member

Sent Rcvd

Prefix activity: ---- ----

Prefixes Current: 3 2 (Consumes 104 bytes)

Prefixes Total: 3 2

Implicit Withdraw: 0 0

Explicit Withdraw: 0 0

Used as bestpath: n/a 2

Used as multipath: n/a 0

Outbound Inbound

Local Policy Denied Prefixes: -------- -------

Bestpath from this peer: 2 n/a

Total: 2 0

Number of NLRIs in the update sent: max 2, min 1

Connections established 1; dropped 0

Last reset never

Connection state is ESTAB, I/O status: 1, unread input bytes: 0

Connection is ECN Disabled, Mininum incoming TTL 0, Outgoing TTL 255

Local host: 2.2.2.2, Local port: 14692

Foreign host: 4.4.4.4, Foreign port: 179

Enqueued packets for retransmit: 0, input: 0 mis-ordered: 0 (0 bytes)

Event Timers (current time is 0xF62D8):

Timer Starts Wakeups Next

Retrans 6 0 0x0

TimeWait 0 0 0x0

AckHold 7 6 0x0

SendWnd 0 0 0x0

KeepAlive 0 0 0x0

GiveUp 0 0 0x0

PmtuAger 0 0 0x0

DeadWait 0 0 0x0

iss: 4085729406 snduna: 4085729684 sndnxt: 4085729684 sndwnd: 16107

irs: 975868670 rcvnxt: 975868940 rcvwnd: 16115 delrcvwnd: 269

SRTT: 178 ms, RTTO: 1209 ms, RTV: 1031 ms, KRTT: 0 ms

minRTT: 212 ms, maxRTT: 428 ms, ACK hold: 200 ms

Flags: active open, nagle

IP Precedence value : 6

Datagrams (max data segment is 536 bytes):

Rcvd: 8 (out of order: 0), with data: 7, total data bytes: 269

Sent: 15 (retransmit: 0, fastretransmit: 0, partialack: 0, Second Congestion: 0), with data: 7, total data bytes: 277

BGP neighbor is 10.1.1.1, remote AS 65500, external link //EBGP邻居

BGP version 4, remote router ID 1.1.1.1

BGP state = Established, up for 00:05:00

Last read 00:00:00, last write 00:00:00, hold time is 180, keepalive interval is 60 seconds

Neighbor capabilities:

Route refresh: advertised and received(old & new)

Address family IPv4 Unicast: advertised and received

Message statistics:

InQ depth is 0

OutQ depth is 0

Sent Rcvd

Opens: 1 1

Notifications: 0 0

Updates: 3 1

Keepalives: 7 7

Route Refresh: 0 0

Total: 11 9

Default minimum time between advertisement runs is 30 seconds

For address family: IPv4 Unicast

BGP table version 8, neighbor version 8/0

Output queue size : 0

Index 1, Offset 0, Mask 0x2

1 update-group member

Sent Rcvd

Prefix activity: ---- ----

Prefixes Current: 4 1 (Consumes 52 bytes)

Prefixes Total: 4 1

Implicit Withdraw: 0 0

Explicit Withdraw: 0 0

Used as bestpath: n/a 1

Used as multipath: n/a 0

Outbound Inbound

Local Policy Denied Prefixes: -------- -------

Bestpath from this peer: 1 n/a

Total: 1 0

Number of NLRIs in the update sent: max 2, min 1

Connections established 1; dropped 0

Last reset never

Connection state is ESTAB, I/O status: 1, unread input bytes: 0

Connection is ECN Disabled, Mininum incoming TTL 0, Outgoing TTL 1

Local host: 10.1.1.2, Local port: 179

Foreign host: 10.1.1.1, Foreign port: 14828

Enqueued packets for retransmit: 0, input: 0 mis-ordered: 0 (0 bytes)

Event Timers (current time is 0xF658C):

Timer Starts Wakeups Next

Retrans 11 0 0x0

TimeWait 0 0 0x0

AckHold 9 2 0x0

SendWnd 0 0 0x0

KeepAlive 0 0 0x0

GiveUp 0 0 0x0

PmtuAger 0 0 0x0

DeadWait 0 0 0x0

iss: 300025546 snduna: 300025871 sndnxt: 300025871 sndwnd: 16060

irs: 1734736732 rcvnxt: 1734736963 rcvwnd: 16154 delrcvwnd: 230

SRTT: 251 ms, RTTO: 796 ms, RTV: 545 ms, KRTT: 0 ms

minRTT: 24 ms, maxRTT: 412 ms, ACK hold: 200 ms

Flags: passive open, nagle, gen tcbs

IP Precedence value : 6

Datagrams (max data segment is 1460 bytes):

Rcvd: 19 (out of order: 0), with data: 9, total data bytes: 230

Sent: 13 (retransmit: 0, fastretransmit: 0, partialack: 0, Second Congestion: 0), with data: 10, total data bytes: 324

以上为R2的BGP邻居信息，详细的说明了邻居的状态和一些参数。

（其他BGP路由器的邻居表略）

然后查看BGP路由表：

R1#show ip bgp

BGP table version is 6, local router ID is 1.1.1.1

Status codes: s suppressed, d damped, 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

*> 172.16.1.0/24 0.0.0.0 0 32768 i

*> 172.16.2.0/24 10.1.1.2 0 0 65000 i

*> 172.16.3.0/24 10.1.1.2 0 65000 i

*> 192.1.1.0 10.1.1.2 0 0 65000 i

*> 193.1.1.0 10.1.1.2 0 65000 i

R2#show ip bgp

BGP table version is 8, local router ID is 172.16.2.1

Status codes: s suppressed, d damped, 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

*> 172.16.1.0/24 10.1.1.1 0 0 65500 i

*> 172.16.2.0/24 0.0.0.0 0 32768 i

r>i172.16.3.0/24 4.4.4.4 0 100 0 i

*> 192.1.1.0 0.0.0.0 0 32768 i

r>i193.1.1.0 4.4.4.4 0 100 0 i

R4#show ip bgp

BGP table version is 7, local router ID is 4.4.4.4

Status codes: s suppressed, d damped, 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

*>i172.16.1.0/24 10.1.1.1 0 100 0 65500 i

*>i172.16.2.0/24 2.2.2.2 0 100 0 i

*> 172.16.3.0/24 0.0.0.0 0 32768 i

r>i192.1.1.0 2.2.2.2 0 100 0 i

*> 193.1.1.0 0.0.0.0 0 32768 i

上面的输出解释：

*号表示存在的网络；

>号表示最佳路径；

前面的i表示通过IBGP学到的路由；

前面的r表示写入到路由信息库失败的路由，可以通过命令show ip bgp rib-failure查看失败原因；

NextHop表示下一跳；

Metric用来表示MED属性；

LocPrf用来表示本地优先级，默认为100；

Weight是cisco专有的一个属性，如果这条路由是自己产生的，Weight为32768，如果是从邻居学到的Weight为0；

Path为BGP的AS PATH属性，用来表示经过的AS。

这里有的前面标记为r的原因是：在写入路由表的时候，ospf同样也有到达该目的地的路由，所以管理距离小的就写入路由表,IBGP的管理距离为200，OSPF的为120，所以使用OSPF的路由。

BGP table version is 7表示BGP的路由表经过了7次的交换和学习路由。

最后查看一下IP路由表：

R1#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

1.0.0.0/24 is subnetted, 1 subnets

C 1.1.1.0 is directly connected, Loopback0

172.16.0.0/24 is subnetted, 3 subnets

C 172.16.1.0 is directly connected, FastEthernet1/0

B 172.16.2.0 [20/0] via 10.1.1.2, 00:03:07

B 172.16.3.0 [20/0] via 10.1.1.2, 00:02:25

10.0.0.0/24 is subnetted, 1 subnets

C 10.1.1.0 is directly connected, FastEthernet0/0

B 193.1.1.0/24 [20/0] via 10.1.1.2, 00:01:55

B 192.1.1.0/24 [20/0] via 10.1.1.2, 00:03:07

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

2.0.0.0/24 is subnetted, 1 subnets

C 2.2.2.0 is directly connected, Loopback0

3.0.0.0/32 is subnetted, 1 subnets

O 3.3.3.3 [110/2] via 192.1.1.2, 00:07:05, FastEthernet1/0

4.0.0.0/32 is subnetted, 1 subnets

O 4.4.4.4 [110/3] via 192.1.1.2, 00:07:05, FastEthernet1/0

172.16.0.0/24 is subnetted, 3 subnets

B 172.16.1.0 [20/0] via 10.1.1.1, 00:04:15

C 172.16.2.0 is directly connected, Loopback1

O 172.16.3.0 [110/3] via 192.1.1.2, 00:07:05, FastEthernet1/0

10.0.0.0/24 is subnetted, 1 subnets

C 10.1.1.0 is directly connected, FastEthernet0/0

O 193.1.1.0/24 [110/2] via 192.1.1.2, 00:07:05, FastEthernet1/0

C 192.1.1.0/24 is directly connected, FastEthernet1/0

R4#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

2.0.0.0/32 is subnetted, 1 subnets

O 2.2.2.2 [110/3] via 193.1.1.1, 00:11:10, FastEthernet0/0

3.0.0.0/32 is subnetted, 1 subnets

O 3.3.3.3 [110/2] via 193.1.1.1, 00:11:10, FastEthernet0/0

4.0.0.0/24 is subnetted, 1 subnets

C 4.4.4.0 is directly connected, Loopback0

172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks

B 172.16.1.0/24 [200/0] via 10.1.1.1, 00:07:52

B 172.16.2.0/24 [200/0] via 2.2.2.2, 00:07:52

C 172.16.3.0/24 is directly connected, FastEthernet1/0

O 172.16.2.1/32 [110/3] via 193.1.1.1, 00:11:10, FastEthernet0/0

10.0.0.0/24 is subnetted, 1 subnets

O 10.1.1.0 [110/3] via 193.1.1.1, 00:11:10, FastEthernet0/0

C 193.1.1.0/24 is directly connected, FastEthernet0/0

O 192.1.1.0/24 [110/2] via 193.1.1.1, 00:11:11, FastEthernet0/0

上面用红色标记的是从BGP学到的路由，下面我们来在R4上ping测试一下：

R4#p 172.16.1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.1.1, timeout is 2 seconds:

U.U.U

Success rate is 0 percent (0/5)

R4#p 10.1.1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 276/352/408 ms

R4#p 10.1.1.2

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10.1.1.2, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 144/205/260 ms

R4#p 172.16.2.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.2.1, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 168/245/356 ms

到172.16.1.1不通，为什么呢？我们debug ip icmp来观察一下：

R4#debug ip icmp

ICMP packet debugging is on

R4#p 172.16.1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.1.1, timeout is 2 seconds:

*Mar 1 00:17:47.947: ICMP: dst (193.1.1.2) host unreachable rcv from 193.1.1.1.U

*Mar 1 00:17:50.051: ICMP: dst (193.1.1.2) host unreachable rcv from 193.1.1.1.U

Success rate is 0 percent (0/5)

R4#

*Mar 1 00:17:52.167: ICMP: dst (193.1.1.2) host unreachable rcv from 193.1.1.1

收到193.1.1.1的目标不可达错误消息，我们到R3上查看一下路由表：

R3#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

2.0.0.0/32 is subnetted, 1 subnets

O 2.2.2.2 [110/2] via 192.1.1.1, 00:07:54, FastEthernet1/0

3.0.0.0/24 is subnetted, 1 subnets

C 3.3.3.0 is directly connected, Loopback0

4.0.0.0/32 is subnetted, 1 subnets

O 4.4.4.4 [110/2] via 193.1.1.2, 00:07:54, FastEthernet0/0

172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks

O 172.16.3.0/24 [110/2] via 193.1.1.2, 00:07:54, FastEthernet0/0

O 172.16.2.1/32 [110/2] via 192.1.1.1, 00:07:54, FastEthernet1/0

10.0.0.0/24 is subnetted, 1 subnets

O 10.1.1.0 [110/2] via 192.1.1.1, 00:07:54, FastEthernet1/0

C 193.1.1.0/24 is directly connected, FastEthernet0/0

C 192.1.1.0/24 is directly connected, FastEthernet1/0

没有到172.16.1.0/24的路由，我们来添加一条静态路由：

Ip route 172.16.1.0 255.255.255.0 192.1.1.1

这样我们再到R4上Ping 172.16.1.1看看：

R4#p 172.16.1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.1.1, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 212/290/408 ms

通了。

其实在一个传输AS中，要求形成一个完全网格的拓扑，就是所有路由器必须都要直连在一起，以防止向在这里出现的中间有一台没有运行BGP的路由器所带来的问题。不过完全网格的限制可以通过其他的手段来解决。

下面我们再来观察一下BGP在建立邻居关系时候的debug信息：

R1#debug ip bgp ipv4 unicast

BGP debugging is on for address family: IPv4 Unicast

R1#clear ip bgp *

R1#

*Mar 1 00:22:32.907: BGPNSF state: 10.1.1.2 went from nsf_not_active to nsf_not_active

*Mar 1 00:22:32.907: BGP: 10.1.1.2 went from Established to Idle //状态从Established变为Idle

*Mar 1 00:22:32.907: %BGP-5-ADJCHANGE: neighbor 10.1.1.2 Down User reset

*Mar 1 00:22:32.907: BGP: 10.1.1.2 closing //关闭邻居关系

*Mar 1 00:22:32.911: BGP: 10.1.1.2 went from Idle to Active //状态从Idle变为Active

*Mar 1 00:22:32.919: BGP: 10.1.1.2 open active, local address 10.1.1.1

*Mar 1 00:22:33.055: BGP: 10.1.1.2 went from Active to OpenSent //状态从Active变为OpenSent

*Mar 1 00:22:33.055: BGP: 10.1.1.2 sending OPEN, version 4, my as: 65500, holdtime 180 seconds //发送OPEN消息

*Mar 1 00:22:33.063: BGP: 10.1.1.2 send message type 1, length (incl. header) 45

*Mar 1 00:22:33.175: BGP: 10.1.1.2 rcv message type 1, length (excl. header) 26

*Mar 1 00:22:33.175: BGP: 10.1.1.2 rcv OPEN, version 4, holdtime 180 seconds //收到OPEN消息

*Mar 1 00:22:33.179: BGP: 10.1.1.2 rcv OPEN w/ OPTION parameter len: 16

*Mar 1 00:22:33.179: BGP: 10.1.1.2 rcvd OPEN w/ optional parameter type 2 (Capability) len 6

*Mar 1 00:22:33.179: BGP: 10.1.1.2 OPEN has CAPABILITY code: 1, length 4

*Mar 1 00:22:33.179: BGP: 10.1.1.2 OPEN has MP_EXT CAP for afi/safi: 1/1

*Mar 1 00:22:33.179: BGP: 10.1.1.2 rcvd OPEN w/ optional parameter type 2 (Capability) len 2

*Mar 1 00:22:33.183: BGP: 10.1.1.2 OPEN has CAPABILITY code: 128, length 0

*Mar 1 00:22:33.183: BGP: 10.1.1.2 OPEN has ROUTE-REFRESH capability(old) for all address-families

*Mar 1 00:22:33.183: BGP: 10.1.1.2 rcvd OPEN w/ optional parameter type 2 (Capability) len 2

*Mar 1 00:22:33.183: BGP: 10.1.1.2 OPEN has CAPABILITY code: 2, length 0

*Mar 1 00:22:33.183: BGP: 10.1.1.2 OPEN has ROUTE-REFRESH capability(new) for all address-families

BGP: 10.1.1.2 rcvd OPEN w/ remote AS 65000

*Mar 1 00:22:33.187: BGP: 10.1.1.2 went from OpenSent to OpenConfirm//状态从OpenSent变为OpenConfirm

*Mar 1 00:22:33.187: BGP: 10.1.1.2 went from OpenConfirm to Established//状态从OpenConfirm变为Established

从上面的debug信息我们可以看到BGP的邻居关系的形成经历了Idle--Active--OpenSent--OpenConfirm—Established这些状态。

实验总结：掌握基本的BGP配置，掌握EBGP/IBGP PEER配置中需要注意的问题和配置方法，并且掌握基本的查看和调试BGP信息和解决简单问题的方法。

本文出自 “★Beckham~23” 博客，请务必保留此出处http://loveme23.blog.51cto.com/7891/53577

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