本文档说明了在本地ATM接口上配置虚拟路径标识符(VPI)和虚拟通道标识符(VCI)以便成功ping通的需要。
将IP地址应用到ATM接口只需将接口配置为路由IP接口。为使ping工作，还要配置永久虚电路(PVC)，以便路由器知道通过哪个虚电路(VC)发送ATM信元。如果没有VC，路由器会报告启用debug命令时的封装故障。通过封装，路由器指的是包绕ping数据包的第2层(L2)报头。
当您对本地接口执行ping操作时，ATM信元实际上会通过物理线路发送出去。如果端到端电路处于活动状态，则ping信元会传到远程路由器端，然后回环。或者，在路径中的某处配置硬件或软件环回，包括在本地接口本身。使用loopback diagnostic命令配置软件环回。
由于ATM VC是点对点的，请考虑以下有关要在其上配置VC的接口类型的点：
主接口 — 支持多条虚电路。每条虚电路需要静态或动态映射，将本地PVC值与远程IP地址匹配。如果没有映射，路由器将报告启用调试后的封装失败错误消息。
多点子接口 — 支持多条虚电路。每条虚电路需要静态或动态映射，将本地PVC值与远程IP地址匹配。如果没有映射，路由器将报告启用调试后的封装失败错误消息。
点对点子接口 — 支持单个VC。由于路由器根据定义假设虚电路另一端有一台设备，因此不需要显式映射。相反，路由器根据路由决策将数据包从VC转发出去。换句话说，路由表告诉路由器IP数据包的下一跳是VC的远程端。
本文档没有任何特定的要求。
本文档不限于特定的软件和硬件版本。
有关文件规则的更多信息请参见“ Cisco技术提示规则”。
下表说明了ping本地接口所需的配置命令，具体取决于该接口是点对点接口还是多点接口。
| 在主ATM接口上配置仅IP地址和无VPI/VCI |
|---|
!
interface ATM4/0
ip address 10.1.1.1 255.255.255.0
no ip directed-broadcast
no atm ilmi-keepalive
!
cs-7204-15a#show atm vc
VCD / Peak Avg/Min Burst
Interface Name VPI VCI Type Encaps Kbps Kbps Cells Sts
cs-7204-15a#show atm map
cs-7204-15a#ping 10.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:
4w2d: IP: s=10.1.1.1 (local), d=10.1.1.1 (ATM4/0), len 100, sending
4w2d: IP: s=10.1.1.1 (local), d=10.1.1.1 (ATM4/0), len 100, encapsulation failed
!--- Router reports encapsulation failure messages because there is no VPI/VCI !--- on which to send the packet.
|
| 在主ATM接口上配置PVC |
|---|
interface ATM4/0
ip address 10.1.1.1 255.255.255.0
no ip directed-broadcast
no atm ilmi-keepalive
pvc 1/32
encapsulation aal5snap
cs-7204-15a#show atm vc
VCD / Peak Avg/Min Burst
Interface Name VPI VCI Type Encaps Kbps Kbps Cells Sts
4/0 4 1 32 PVC SNAP 149760 UP
cs-7204-15a#show atm map
cs-7204-15a#
debug ip packet
IP packet debugging is on
cs-7204-15a#ping 10.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:
4w2d: IP: s=10.1.1.1 (local), d=10.1.1.1 (ATM4/0), len 100, sending
4w2d: IP: s=10.1.1.1 (local), d=10.1.1.1 (ATM4/0), len 100, encapsulation failed
!--- Although this configures a PVC, either a dynamic or !--- static mapping is still needed between the L2 and Layer 3 (L3) addresses.
|
| 在PVC上配置静态映射语句 |
|---|
interface ATM4/0 ip address 10.1.1.1 255.255.255.0 no ip directed-broadcast no atm ilmi-keepalive pvc 1/32 protocol ip 10.1.1.1 !--- This configures a static map back to the local interface. !--- Normally, the map statement points to the remote IP address. encapsulation aal5snap cs-7204-15a#show atm map Map list ATM4/0pvc4 : PERMANENT ip 10.1.1.1 maps to VC 4, VPI 1, VCI 32, ATM4/0 cs-7204-15a#ping 10.1.1.1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds: 5w1d: IP: s=10.1.1.1 (local), d=10.1.1.1 (ATM4/0), len 100, sending. 5w1d: IP: s=10.1.1.1 (local), d=10.1.1.1 (ATM4/0), len 100, sending. !--- The router now sends the packets. However, since there is not a !--- remote end in the lab setup, the pings fail. |
| 在主接口上配置环回诊断 |
|---|
interface ATM4/0 ip address 10.1.1.1 255.255.255.0 no ip directed-broadcast loopback diagnostic !--- This configures a software loopback with the loopback diag command. no atm ilmi-keepalive pvc 1/32 protocol ip 10.1.1.1 encapsulation aal5snap cs-7204-15a#show atm map Map list ATM4/0pvc4 : PERMANENT ip 10.1.1.1 maps to VC 4, VPI 1, VCI 32, ATM4/0 cs-7204-15a#ping 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 = 1/2/4 ms cs-7204-15a# 5w1d: IP: s=10.1.1.1 (local), d=10.1.1.1 (ATM4/0), len 100, sending 5w1d: IP: s=10.1.1.1 (ATM4/0), d=10.1.1.1 (ATM4/0), len 100, rcvd 3 5w1d: IP: s=10.1.1.1 (local), d=10.1.1.1 (ATM4/0), len 100, sending 5w1d: IP: s=10.1.1.1 (ATM4/0), d=10.1.1.1 (ATM4/0), len 100, rcvd 3 !--- The pings are successful. Note that the local interface both !--- receives its own Internet Control Message Protocol (ICMP) echo and echo-reply. |
| 配置ATM多点接口 |
|---|
interface ATM4/0 no ip address no ip directed-broadcast loopback diagnostic no atm ilmi-keepalive ! interface ATM4/0.1 multipoint ip address 10.1.1.1 255.255.255.0 no ip directed-broadcast pvc 1/32 protocol ip 10.1.1.1 !--- This configures a static map or use inverse Address Resolution Protocol (ARP) on a multipoint subinterface. encapsulation aal5snap cs-7204-15a#show atm map Map list ATM4/0.1pvc5 : PERMANENT ip 10.1.1.1 maps to VC 5, VPI 1, VCI 32, ATM4/0.1 cs-7204-15a#ping 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 = 1/2/4 ms cs-7204-15a# 5w1d: IP: s=10.1.1.1 (local), d=10.1.1.1 (ATM4/0.1), len 100, sending 5w1d: IP: s=10.1.1.1 (ATM4/0.1), d=10.1.1.1 (ATM4/0.1), len 100, rcvd 3 5w1d: IP: s=10.1.1.1 (local), d=10.1.1.1 (ATM4/0.1), len 100, sending 5w1d: IP: s=10.1.1.1 (ATM4/0.1), d=10.1.1.1 (ATM4/0.1), len 100, rcvd 3 |
| 点对点子接口 |
|---|
interface ATM4/0 no ip address no ip directed-broadcast loopback diagnostic !--- Use the loopback diagnostic command if !--- the PVC is not configured end to end. no atm ilmi-keepalive ! interface ATM4/0.2 point-to-point ip address 10.1.1.1 255.255.255.0 no ip directed-broadcast pvc 1/32 encapsulation aal5snap !--- Point-to-point interfaces do not need a static mapping or inverse ARP. cs-7204-15a#show atm map cs-7204-15a#ping 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 = 1/2/4 ms cs-7204-15a# 00:11:03: IP: s=10.1.1.1 (local), d=10.1.1.1 (ATM4/0.2), len 100, sending 00:11:03: IP: s=10.1.1.1 (ATM4/0.2), d=10.1.1.1 (ATM4/0.2), len 100, rcvd 3 00:11:03: IP: s=10.1.1.1 (local), d=10.1.1.1 (ATM4/0.2), len 100, sending 00:11:03: IP: s=10.1.1.1 (ATM4/0.2), d=10.1.1.1 (ATM4/0.2), len 100, rcvd 3 |