Dot1Q/L2P隧道上的丢包

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已更新: 2012 年 11 月 6 日

文档 ID:113632

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简介

本文档通过案例研究讨论了Cisco IOS®中由于网络设计不佳而导致的Dot1Q/L2P隧道丢包^故障的故障排除。

先决条件

要求

Cisco 建议您了解以下主题：

关于Dot1Q隧道的基本知识
OSPF的基本知识

使用的组件

本文档不限于特定的软件或硬件版本。

本文档中的信息都是基于特定实验室环境中的设备编写的。本文档中使用的所有设备最初均采用原始（默认）配置。如果您使用的是真实网络，请确保您已经了解所有命令的潜在影响。

规则

有关文档规则的详细信息，请参阅 Cisco 技术提示规则。

网络图

在此网络设置中，路由器7600-Core的接口Gi1/44和Gi1/43将路由器分别设置为单臂路由器3400-Metro-1的Fa0/13和Fa0/12。在7600-Dot1Q交换机中，接口Gi9/44和Gi 9/45已启用Dot1q隧道模式。在3400 — 城域边缘上创建SVI vlan接口，Fa0/13和Fa0/12配置为中继端口。路由器使用OSPF相互通信。

7609核心
! version 15.0 hostname 7609-CORE interface GigabitEthernet1/43 mtu 9216 no ip address no ip redirects no ip proxy-arp load-interval 60 carrier-delay 2 flowcontrol send off storm-control broadcast level 1.00 ! interface GigabitEthernet1/43.3503 encapsulation dot1Q 3503 ip address 172.16.41.17 255.255.255.252 no ip redirects no ip proxy-arp ip mtu 1500 ip ospf authentication-key 7 072C0E6B6B272D ip ospf network point-to-point ip ospf hello-interval 3 ip ospf dead-interval 10 ! ! interface GigabitEthernet1/44 mtu 9216 no ip address no ip redirects no ip proxy-arp load-interval 60 carrier-delay 2 flowcontrol send off storm-control broadcast level 1.00 ! interface GigabitEthernet1/44.3803 encapsulation dot1Q 3803 ip address 172.16.73.137 255.255.255.248 secondary ip address 172.16.41.21 255.255.255.252 no ip redirects no ip proxy-arp ip mtu 1500 ip ospf authentication-key 7 072C0E6B6B272D ip ospf network point-to-point ip ospf cost 5 ip ospf hello-interval 3 ip ospf dead-interval 10 !--- Output omitted. ! end

7609核心

!
version 15.0
hostname 7609-CORE
interface GigabitEthernet1/43
 mtu 9216
 no ip address
 no ip redirects
 no ip proxy-arp
 load-interval 60
 carrier-delay 2
 flowcontrol send off
 storm-control broadcast level 1.00
!
interface GigabitEthernet1/43.3503
 encapsulation dot1Q 3503
 ip address 172.16.41.17 255.255.255.252
 no ip redirects
 no ip proxy-arp
 ip mtu 1500
 ip ospf authentication-key 7 072C0E6B6B272D
 ip ospf network point-to-point
 ip ospf hello-interval 3
 ip ospf dead-interval 10
!
!
interface GigabitEthernet1/44
 mtu 9216
 no ip address
 no ip redirects
 no ip proxy-arp
 load-interval 60
 carrier-delay 2
 flowcontrol send off
 storm-control broadcast level 1.00
!
interface GigabitEthernet1/44.3803
 encapsulation dot1Q 3803
 ip address 172.16.73.137 255.255.255.248 secondary
 ip address 172.16.41.21 255.255.255.252
 no ip redirects
 no ip proxy-arp
 ip mtu 1500
 ip ospf authentication-key 7 072C0E6B6B272D
 ip ospf network point-to-point
 ip ospf cost 5
 ip ospf hello-interval 3
 ip ospf dead-interval 10

!--- Output omitted.

!
end

7609 DOT1Q
! version 12.2 ! interface GigabitEthernet9/44 switchport switchport access vlan 24 switchport mode dot1q-tunnel mtu 9216 load-interval 60 carrier-delay 2 flowcontrol send off storm-control broadcast level 1.00 l2protocol-tunnel cdp l2protocol-tunnel stp l2protocol-tunnel vtp no cdp enable spanning-tree portfast disable spanning-tree bpdufilter enable ! ! interface GigabitEthernet9/45 switchport switchport access vlan 24 switchport mode dot1q-tunnel mtu 9216 load-interval 60 carrier-delay 2 flowcontrol send off storm-control broadcast level 1.00 l2protocol-tunnel cdp l2protocol-tunnel stp l2protocol-tunnel vtp no cdp enable spanning-tree portfast disable spanning-tree bpdufilter enable ! !--- Output omitted. ! end

7609 DOT1Q

!
version 12.2
!
interface GigabitEthernet9/44
  switchport
 switchport access vlan 24
 switchport mode dot1q-tunnel
 mtu 9216
 load-interval 60
 carrier-delay 2
 flowcontrol send off
 storm-control broadcast level 1.00
 l2protocol-tunnel cdp
 l2protocol-tunnel stp
 l2protocol-tunnel vtp
 no cdp enable
 spanning-tree portfast disable
 spanning-tree bpdufilter enable
!
!
interface GigabitEthernet9/45
 switchport
 switchport access vlan 24
 switchport mode dot1q-tunnel
 mtu 9216
 load-interval 60
 carrier-delay 2
 flowcontrol send off
 storm-control broadcast level 1.00
 l2protocol-tunnel cdp
 l2protocol-tunnel stp
 l2protocol-tunnel vtp
 no cdp enable
 spanning-tree portfast disable
 spanning-tree bpdufilter enable
!

!--- Output omitted.

!
end

3400-Metro-1
! version 12.2 ! interface FastEthernet0/3 port-type nni switchport trunk allowed vlan 1052,3503 switchport mode trunk load-interval 60 ! interface FastEthernet0/4 port-type nni switchport trunk allowed vlan 1052,3803 switchport mode trunk load-interval 60 ! ! interface FastEthernet0/12 port-type nni switchport trunk allowed vlan 2-4094 switchport mode trunk ! interface FastEthernet0/13 port-type nni switchport trunk allowed vlan 2-4094 switchport mode trunk ! end

3400-Metro-1

!
version 12.2
!
interface FastEthernet0/3
  port-type nni
 switchport trunk allowed vlan 1052,3503
 switchport mode trunk
 load-interval 60
!
interface FastEthernet0/4
 port-type nni
 switchport trunk allowed vlan 1052,3803
 switchport mode trunk
 load-interval 60
!
!
interface FastEthernet0/12
 port-type nni
 switchport trunk allowed vlan 2-4094
 switchport mode trunk

!
interface FastEthernet0/13
 port-type nni
 switchport trunk allowed vlan 2-4094
 switchport mode trunk
!
end

3400 — 城域边缘
! version 12.2 ! interface FastEthernet0/12 port-type nni switchport mode trunk load-interval 60 storm-control broadcast level 1.00 spanning-tree portfast disable spanning-tree bpdufilter disable ! interface FastEthernet0/13 port-type nni switchport mode trunk load-interval 60 storm-control broadcast level 1.00 spanning-tree portfast disable spanning-tree bpdufilter disable ! ! interface Vlan3503 ip address 172.16.41.18 255.255.255.252 no ip redirects no ip proxy-arp ip ospf authentication-key 7 072C0E6B6B272D ip ospf network point-to-point ip ospf hello-interval 3 ip ospf dead-interval 10 ! interface Vlan3803 ip address 172.16.73.139 255.255.255.248 secondary ip address 172.16.41.22 255.255.255.252 no ip redirects no ip proxy-arp ip ospf authentication-key 7 072C0E6B6B272D ip ospf network point-to-point ip ospf cost 5 ip ospf hello-interval 3 ip ospf dead-interval 10 ! !--- Output omitted. ! end

3400 — 城域边缘

!
version 12.2
!
interface FastEthernet0/12
 port-type nni
 switchport mode trunk
 load-interval 60
 storm-control broadcast level 1.00
 spanning-tree portfast disable
 spanning-tree bpdufilter disable
!
interface FastEthernet0/13
 port-type nni
 switchport mode trunk
 load-interval 60
 storm-control broadcast level 1.00
 spanning-tree portfast disable
 spanning-tree bpdufilter disable
!
!
interface Vlan3503
 ip address 172.16.41.18 255.255.255.252
 no ip redirects
 no ip proxy-arp
 ip ospf authentication-key 7 072C0E6B6B272D
 ip ospf network point-to-point
 ip ospf hello-interval 3
 ip ospf dead-interval 10
!
interface Vlan3803
 ip address 172.16.73.139 255.255.255.248 secondary
 ip address 172.16.41.22 255.255.255.252
 no ip redirects
 no ip proxy-arp
 ip ospf authentication-key 7 072C0E6B6B272D
 ip ospf network point-to-point
 ip ospf cost 5
 ip ospf hello-interval 3
 ip ospf dead-interval 10
!

!--- Output omitted.

!
end

观察

当数据包通过Dot1Q隧道时，会发生随机Ping丢弃。但是，接口上没有输入/输出丢弃，也没有物理层问题的症状。发出show interface <interface >命令以检查接口上的输入/输出丢弃：

7609-Dot1Q#show interface gi9/44 

!--- Output omitted.

 Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
    0 input errors, 0 CRC, 1 frame, 0 overrun, 0 ignored
    0 output errors, 0 collisions, 1 interface resets
    0 lost carrier, 0 no carrier, 0 PAUSE output

!--- Output omitted.

当从城域边缘发出约100个Ping的ICMP流量时，核心层仅接收95个回显，这表明ICMP数据包在路径中被丢弃。

Metro-Edge#ping 172.16.41.21 re 100

Type escape sequence to abort.
Sending 100, 100-byte ICMP Echos to 172.16.41.21, timeout is 2 seconds:
.....!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Success rate is 95 percent (95/100), round-trip min/avg/max = ½/9 ms

注意：7609中的show ip traffic命令显示，仅接收95条回声，而城域边缘中只接收100条回声。

show ip traffic
城域边缘 ICMP statistics: Rcvd: 0 format errors, 0 checksum errors, 0 redirects, 0 unreachable 0 echo, 95 echo reply, 0 mask requests, 0 mask replies, 0 quench 0 parameter, 0 timestamp, 0 info request, 0 other 0 irdp solicitations, 0 irdp advertisements Sent: 0 redirects, 0 unreachable, 100 echo, 0 echo reply 0 mask requests, 0 mask replies, 0 quench, 0 timestamp 0 info reply, 0 time exceeded, 0 parameter problem 0 irdp solicitations, 0 irdp advertisements !--- The above output shows that 100 echos are sent !--- but received 95 replies from 7609-Core. 在7609-Core中 ICMP statistics: Rcvd: 0 format errors, 0 checksum errors, 0 redirects, 0 unreachable 95 echo, 0 echo reply, 0 mask requests, 0 mask replies, 0 quench 0 parameter, 0 timestamp, 0 info request, 0 other 0 irdp solicitations, 0 irdp advertisements Sent: 0 redirects, 0 unreachable, 0 echo, 95 echo reply 0 mask requests, 0 mask replies, 0 quench, 0 timestamp 0 info reply, 0 time exceeded, 0 parameter problem 0 irdp solicitations, 0 irdp advertisements

show ip traffic

城域边缘

ICMP statistics:
  Rcvd: 0 format errors, 0 checksum errors, 0 redirects, 0 unreachable
        0 echo, 95 echo reply, 0 mask requests, 0 mask replies, 0 quench
        0 parameter, 0 timestamp, 0 info request, 0 other
        0 irdp solicitations, 0 irdp advertisements
  Sent: 0 redirects, 0 unreachable, 100 echo, 0 echo reply
        0 mask requests, 0 mask replies, 0 quench, 0 timestamp
        0 info reply, 0 time exceeded, 0 parameter problem
        0 irdp solicitations, 0 irdp advertisements

!--- The above output shows that 100 echos are sent !--- but received 95 replies from 7609-Core.

在7609-Core中

ICMP statistics:
  Rcvd: 0 format errors, 0 checksum errors, 0 redirects, 0 unreachable
        95 echo, 0 echo reply, 0 mask requests, 0 mask replies, 0 quench
        0 parameter, 0 timestamp, 0 info request, 0 other
        0 irdp solicitations, 0 irdp advertisements
  Sent: 0 redirects, 0 unreachable, 0 echo, 95 echo reply
        0 mask requests, 0 mask replies, 0 quench, 0 timestamp
        0 info reply, 0 time exceeded, 0 parameter problem
        0 irdp solicitations, 0 irdp advertisements

故障排除

检验MAC地址是否正确学习以排除数据包丢弃故障。

使用show mac address table 命令验证MAC地址条目。

要成功执行Ping操作

7609-DOT1q#sh mac-address-table address E05F.B972.1F00 all
Legend: * - primary entry
age - seconds since last seen
n/a - not available
vlan mac address type learn age ports
------+----------------+--------+-----+----------+--------------------------
Active Supervisor:
* 24 e05f.b972.1f00 dynamic Yes 0 Gi9/44

!--- This output displays the MAC address learnt !--- and its associated port, in this case the associated !--- port for successful ping is Gi9/44.

对于失败Ping

7609-DOT1q#sh mac-address-table address E05F.B972.1F00 all
Legend: * - primary entry
age - seconds since last seen
n/a - not available
vlan mac address type learn age ports
------+----------------+--------+-----+----------+--------------------------
Active Supervisor:
* 24 e05f.b972.1f00 dynamic Yes 5 Gi9/45

!--- This output displays the MAC address learnt !--- and its associated port, in this case, !--- the port number is Gi9/45.

要查看详细的MAC索引编程，请使用show mac-address-table命令。

7609-DOT1q#sh mac-address-table address E05F.B972.1F00 det

MAC Table shown in details
========================================

PI_E RM RMA Type Alw-Lrn Trap Modified Notify Capture Flood Mac Address Age Pvlan SWbits Index XTag
----+---+---+----+-------+----+--------+------+-------+------+--------------+----+------+------+----

Active Supervisor:

Yes No No DY No No Yes No No No e05f.b972.1f00 0xE0 24 0 0x22C 0

发出Remote login 开关和test mcast ltl-info index <Index number>命令，以便知道前一个HEX值表示的端口号。

7609-DOT1q-sp#test mcast ltl-info index 22B
index 0x22B contain ports 9/44
7609-DOT1q-sp#test mcast ltl-info index 22C
index 0x22C contain ports 9/45

!--- The output shows that hex number 22B !--- points to 9/44 port and hex 22C points to 9/45.

对于ping失败，源和目标索引是相同的端口，因此是丢弃。当在7600上使用mac-address-table notification mac-move命令启用Mac-move时，它会显示两个不同端口之间的MAC摆动，这是错误消息：

注意：由于6500/7600为交换机使用一个通用MAC地址，因此不同端口之间分配的MAC地址相同。show catalyst 6000 chassis-mac-address命令显示保留的交换机MAC地址。

* Jul 2 10:29:44.011: %MAC_MOVE-SP-4-NOTIF: Host e05f.b972.1f00 in 
vlan 24 is flapping between port Gi9/45 and port Gi9/44

!--- The previous error message indicates !--- that the same MAC address is assigned between !--- two different ports: Gi9/45 and port Gi9/44.

解决方案

上一个网络是在同一交换机上具有DOT1Q隧道终端的全网状网络设置。在这种网络设置中，需要MAC抖动。为了避免MAC抖动，可以实施其中一种解决方案。

将隧道终端移动到其他交换机，例如，封装和解封应发生在不同的交换机。
VLAN修剪可以用来调节任何中继端口中的VLAN。

Dot1Q/L2P隧道上的丢包

下载选项

非歧视性语言

关于此翻译

目录

简介

先决条件

要求

使用的组件

规则

网络图

配置

观察

故障排除

解决方案

相关信息

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