Frame-relay综合实验-1

2007-09-19 12:47:00

　标签：Frame-relay　　　[推送到技术圈]

Frame-relay综合实验-1

试验拓扑：

理解试验拓扑：本试验拓扑为部分网格，也叫hub and sopke，R2和R3分别通过frame云和R1相连，R2与R3之间没有连接。

试验目的：使用全物理接口封装frame-relay，然后在R2上ping R3，观察出现的问题和掌握解决问题的方法。

实验配置：

Frame-relay Switch：

FRSW(config)#frame-relay switching

FRSW(config)#int s1/0

FRSW(config-if)#enca frame-relay

FRSW(config-if)#frame-relay intf-type dce

FRSW(config-if)#clock rate 5600

FRSW(config-if)#frame-relay route 301 interface s1/1 103

FRSW(config-if)#frame-relay route 302 interface s1/2 203

FRSW(config-if)#no shu

FRSW(config-if)#exit

FRSW(config)#int s1/1

FRSW(config-if)#encapsulation frame-relay

FRSW(config-if)#frame-relay intf-type dce

FRSW(config-if)#clock rate 5600

FRSW(config-if)#frame-relay route 103 interface s1/0 301

FRSW(config-if)#no shu

FRSW(config-if)#exit

FRSW(config)#int s1/2

FRSW(config-if)#encapsulation frame-relay

FRSW(config-if)#frame-relay intf-type dce

FRSW(config-if)#clock rate 5600

FRSW(config-if)#frame-relay route 203 interface s1/0 302

FRSW(config-if)#no shu

R1：

R1(config)#int s1/0

R1(config-if)#ip add 172.16.3.3 255.255.255.0

R1(config-if)#enca frame-relay

R1(config-if)#no shu

R2：

R2(config)#int s1/0

R2(config-if)#ip add 172.16.3.1 255.255.255.0

R2(config-if)#enca fram

R2(config-if)#no shu

R3：

R3(config)#int s1/0

R3(config-if)#ip add 172.16.3.2 255.255.255.0

R3(config-if)#enca fram

R3(config-if)#no shu

以上为frame-relay基本配置，下面我们用R2分别ping R1 and R3：

R2#ping 172.16.3.3

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.3.3, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 192/295/372 ms

可以ping通R1，是因为我们有到R1的映射。

R2#debug ip pac

IP packet debugging is on

R2#ping 172.16.3.2

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.3.2, timeout is 2 seconds:

*Mar 1 00:02:43.959: IP: tableid=0, s=172.16.3.1 (local), d=172.16.3.2 (Serial1/0), routed via RIB

*Mar 1 00:02:43.963: IP: s=172.16.3.1 (local), d=172.16.3.2 (Serial1/0), len 100, sending

*Mar 1 00:02:43.963: IP: s=172.16.3.1 (local), d=172.16.3.2 (Serial1/0), len 100, encapsulation failed.

*Mar 1 00:02:45.959: IP: tableid=0, s=172.16.3.1 (local), d=172.16.3.2 (Serial1/0), routed via RIB

*Mar 1 00:02:45.959: IP: s=172.16.3.1 (local), d=172.16.3.2 (Serial1/0), len 100, sending

*Mar 1 00:02:45.959: IP: s=172.16.3.1 (local), d=172.16.3.2 (Serial1/0), len 100, encapsulation failed.

*Mar 1 00:02:47.959: IP: tableid=0, s=172.16.3.1 (local), d=172.16.3.2 (Serial1/0), routed via RIB

*Mar 1 00:02:47.959: IP: s=172.16.3.1 (local), d=172.16.3.2 (Serial1/0), len 100, sending

*Mar 1 00:02:47.963: IP: s=172.16.3.1 (local), d=172.16.3.2 (Serial1/0), len 100, encapsulation failed.

*Mar 1 00:02:49.959: IP: tableid=0, s=172.16.3.1 (local), d=172.16.3.2 (Serial1/0), routed via RIB

*Mar 1 00:02:49.959: IP: s=172.16.3.1 (local), d=172.16.3.2 (Serial1/0), len 100, sending

*Mar 1 00:02:49.959: IP: s=172.16.3.1 (local), d=172.16.3.2 (Serial1/0), len 100, encapsulation failed.

*Mar 1 00:02:51.959: IP: tableid=0, s=172.16.3.1 (local), d=172.16.3.2 (Serial1/0), routed via RIB

*Mar 1 00:02:51.959: IP: s=172.16.3.1 (local), d=172.16.3.2 (Serial1/0), len 100, sending

*Mar 1 00:02:51.959: IP: s=172.16.3.1 (local), d=172.16.3.2 (Serial1/0), len 100, encapsulation failed.

无法ping通R3,debug信息显示“encapsulation failed”，说明链路层有问题，然后用debug fram pac命令显示链路层调试信息：

R2#debug fram pac

Frame Relay packet debugging is on

R2#ping 172.16.3.2

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.3.2, timeout is 2 seconds:

*Mar 1 00:03:03.835: Serial1/0:Encaps failed--no map entry link 7(IP).

*Mar 1 00:03:05.831: Serial1/0:Encaps failed--no map entry link 7(IP).

*Mar 1 00:03:07.831: Serial1/0:Encaps failed--no map entry link 7(IP).

*Mar 1 00:03:09.831: Serial1/0:Encaps failed--no map entry link 7(IP).

*Mar 1 00:03:11.831: Serial1/0:Encaps failed--no map entry link 7(IP).

Success rate is 0 percent (0/5)

我们看到debug信息显示“:Encaps failed--no map entry link”，说明没有到R3的映射，因为我们这里采用的是InverseARP来动态映射IP和DLCI的，由于InverseARP无法映射远端spoke的IP，所以在这里我们需要用frame-relay map命令手动添加，如下：

R2(config)#int s1/0

R2(config-if)#fram map ip 172.16.3.2 103 broadcast

再观察ping R3时调试信息：

R2#ping 172.16.3.2

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.3.2, timeout is 2 seconds:

*Mar 1 00:04:38.395: Serial1/0(o): dlci 103(0x1871), pkt type 0x800(IP), datagramsize 104

*Mar 1 00:04:38.603: Serial1/0(i): dlci 103(0x1871), pkt type 0x800, datagramsize 60.

*Mar 1 00:04:40.391: Serial1/0(o): dlci 103(0x1871), pkt type 0x800(IP), datagramsize 104.

*Mar 1 00:04:42.391: Serial1/0(o): dlci 103(0x1871), pkt type 0x800(IP), datagramsize 104.

*Mar 1 00:04:44.391: Serial1/0(o): dlci 103(0x1871), pkt type 0x800(IP), datagramsize 104.

*Mar 1 00:04:46.391: Serial1/0(o): dlci 103(0x1871), pkt type 0x800(IP), datagramsize 104.

Success rate is 0 percent (0/5)

成功发送出去，但是还是无法ping通，我们到R3上观察调试信息：

R3#debug fram pac

Frame Relay packet debugging is on

R3#

*Mar 1 00:03:49.847: Serial1/0(i): dlci 203(0x30B1), pkt type 0x800, datagramsize 104

*Mar 1 00:03:49.847: Serial1/0:Encaps failed--no map entry link 7(IP)

*Mar 1 00:03:51.863: Serial1/0(i): dlci 203(0x30B1), pkt type 0x800, datagramsize 104

*Mar 1 00:03:51.863: Serial1/0:Encaps failed--no map entry link 7(IP)

同样出现了没有做映射的问题，因为ICMP ECHO包需要返回应答，所以必须在R3上也要手动添加到R2的映射：

R3(config)#int s1/0

R3(config-if)#fram map ip 172.16.3.1 203 broadcast

然后在R2上ping R3：

R2#ping 172.16.3.2

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.3.2, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 360/392/432 ms

OK，可以ping通。能ping通的原因是spoke路由器把包发给hub路由器，由于hub路由器有到全部spoke路由器的映射，所以它可以把包成功的转发到目的spoke路由器。

总结：在部分网格/hub and spoke拓扑结构中，如果全部采用物理接口来配置frame-relay的话，需要在所有的spoke路由器上添加到其余所有spoke路由器的映射。

本文出自 “★Beckham~23” 博客，请务必保留此出处http://loveme23.blog.51cto.com/7891/43208

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