【网工案例库】碰到交换机L2转发故障怎么办？

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发布于 2023-11-13 21:13:43

1900

发布于 2023-11-13 21:13:43

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华三交换机经常出现L2转发故障，本文针对L2转发故障做一个简单的总结

故障描述

华三S12500交换机与属于同一个网段、使用相同VLAN的设备之间，二层流量丢包/不通。报文在设备上进行二层转发的条件是报文的目的MAC与交换机自身的MAC不相等。注意：交换机自身的MAC地址有多个，属于同一个地址段，比如下面显示的是交换机VLAN接口的MAC。

[Sysname]display interface vlan-interface 10

Vlan-interface10 current state: UP

Line protocol current state: UP

Description: Vlan-interface10 Interface

The Maximum Transmit Unit is 1500

Internet Address is 10.0.0.1/24 Primary

IP Packet Frame Type: PKTFMT_ETHNT_2,  Hardware Address: 00e0-fc00-6503

IPv6 Packet Frame Type: PKTFMT_ETHNT_2,  Hardware Address: 00e0-fc00-6503

Last clearing of counters:  Never

    Last 300 seconds input rate: 0 bytes/sec, 0 bits/sec, 0 packets/sec

    Last 300 seconds output rate: 0 bytes/sec, 0 bits/sec, 0 packets/sec

    0 packets input, 0 bytes, 0 drops

    0 packets output, 0 bytes, 0 drops

故障处理步骤

1、配置检查

检查二层配置是否正常，如：

VLAN/PVID
报文过滤
报文重定向
流量监管（CAR）
流量整形（GTS）
未知单播/组播/广播报文抑制

2、MAC检查

检查MAC学习的端口是否正确，是否存在环路导致MAC学习到错误端口，必要时可以配置静态MAC来快速恢复业务。

<Sysname>display mac-address

MAC ADDR        VLAN ID   STATE            PORT INDEX              AGING TIME(s)

000f-e259-79c0    25      Learned          GigabitEthernet2/15/0/1      AGING

00e0-fc12-3456    25      Learned          GigabitEthernet2/15/0/1      AGING

0023-8956-7b00  3102      Learned          Ten-GigabitEthernet2/4/0/1   AGING

0023-8956-7b00  3202      Learned          Ten-GigabitEthernet2/4/0/8   AGING

 

  ---  4 mac address(es) found  ---

3、L2报文计数检查

统计入端口计数

[Sysname]qos traffic-counter inbound counter0 slot 3 interface Gigabitethernet 3/0/1

多次查询计数观察入端口discarded丢包计数是否增加。如丢包计数持续增加，请参照表1计数描述检查端口配置是否正确；

[Sysname]display qos traffic-counter inbound counter0 slot 3

Slot 3 inbound counter0 mode:

 Interface: GigabitEthernet3/0/1

 VLAN: all

 

Traffic-counter summary:

 Bridge in frames: 0 packets

 Bridge local discarded: 0 packets

 Bridge vlan ingress filter discarded: 0 packets

 Bridge security filter discarded: 0 packets

表1入端口统计计数描述表

配置统计出端口计数

[Sysname]qos traffic-counter outbound counter0 slot 4 interface Gigabitethernet 4/0/1

多次查询计数观察出端口discarded丢包计数是否增加。请参照表2计数描述检查端口配置是否正确；

[Sysname]display qos traffic-counter outbound counter0 slot 4

Slot 4 outbound counter0 mode:

 Interface: GigabitEthernet4/0/1

 VLAN: all

 Local precedence: all

 Drop priority: all

 

Traffic-counter summary:

 Unicast: 0 packets

 Multicast: 0 packets

 Broadcast: 0 packets

 Control packets: 0 packets

 Bridge egress filtered packets: 0 packets

 Tail drop packets: 0 packets

 Multicast Tail drop packets: 2 packets

 Forward restrictions packets: 0 packets