两台Linux服务器compute2和computer6的指定网卡ens4np0和enp101s0np1通过Dell交换机二层互联，并且配置同网段的IP地址，在两个服务器上分别指定网口ens4np0和enp101s0np1互ping，结果在两台服务器上都始终无法ping通，接下来将通过抓包来进行问题分析定位。
两台服务器的ens4np0和enp101s0np1网卡采取简单二层连接，组网拓扑图如下所示：
[root@compute2 ~]# ip a
1: lo: mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eno3: mtu 1500 qdisc mq state UP group default qlen 1000
link/ether b0:26:28:ff:c7:5a brd ff:ff:ff:ff:ff:ff
altname enp1s0f0
inet 10.8.8.2/24 brd 10.8.13.255 scope global dynamic eno3
valid_lft 6131sec preferred_lft 6131sec
inet6 fe80::b226:28ff:feff:c75a/64 scope link
valid_lft forever preferred_lft forever
3: eno4: mtu 1500 qdisc mq state DOWN group default qlen 1000
link/ether b0:26:28:ff:c7:5b brd ff:ff:ff:ff:ff:ff
altname enp1s0f1
4: eno1np0: mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether b0:26:28:ff:c7:5c brd ff:ff:ff:ff:ff:ff
altname enp25s0f0np0
5: eno2np1: mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether b0:26:28:ff:c7:5d brd ff:ff:ff:ff:ff:ff
altname enp25s0f1np1
14: bond2: mtu 1600 qdisc noqueue state DOWN group default qlen 1000
link/ether 82:94:2d:68:e1:26 brd ff:ff:ff:ff:ff:ff
25: docker0: mtu 1500 qdisc noqueue state DOWN group default
link/ether 02:42:ee:5f:4f:68 brd ff:ff:ff:ff:ff:ff
inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
valid_lft forever preferred_lft forever
26: ovs-system: mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether e2:ba:b8:a9:7b:23 brd ff:ff:ff:ff:ff:ff
27: mirror0: mtu 1400 qdisc noqueue state UNKNOWN group default qlen 1000
link/ether fe:a4:0a:5b:9f:bd brd ff:ff:ff:ff:ff:ff
inet6 fe80::fca4:aff:fe5b:9fbd/64 scope link
valid_lft forever preferred_lft forever
28: ovn0: mtu 1400 qdisc noqueue state UNKNOWN group default qlen 1000
link/ether 00:00:00:84:fd:41 brd ff:ff:ff:ff:ff:ff
inet 100.64.0.2/16 brd 100.64.255.255 scope global ovn0
valid_lft forever preferred_lft forever
inet6 fe80::200:ff:fe84:fd41/64 scope link
valid_lft forever preferred_lft forever
29: genev_sys_6081: mtu 65000 qdisc noqueue master ovs-system state UNKNOWN group default qlen 1000
link/ether 92:de:04:77:6a:b5 brd ff:ff:ff:ff:ff:ff
inet6 fe80::90de:4ff:fe77:6ab5/64 scope link
valid_lft forever preferred_lft forever
30: br-int: mtu 1400 qdisc noop state DOWN group default qlen 1000
link/ether 86:b4:b3:6f:b5:3a brd ff:ff:ff:ff:ff:ff
39: ens1: mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether 32:14:eb:bd:2a:15 brd ff:ff:ff:ff:ff:ff
altname enp59s0
40: ens1np0: mtu 1500 qdisc noqueue state DOWN group default qlen 1000
link/ether 00:15:4d:16:66:d5 brd ff:ff:ff:ff:ff:ff
altname enp59s0np0
41: ens1np1: mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether 00:15:4d:16:66:d6 brd ff:ff:ff:ff:ff:ff
altname enp59s0np1
42: eth3: mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether 92:cd:7a:0b:c7:a0 brd ff:ff:ff:ff:ff:ff
43: ens4: mtu 1500 qdisc mq state UP group default qlen 1000
link/ether 06:fc:64:f0:c6:77 brd ff:ff:ff:ff:ff:ff
altname enp175s0
inet6 fe80::4fc:64ff:fef0:c677/64 scope link
valid_lft forever preferred_lft forever
44: ens4np0: mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 00:15:4d:16:20:6a brd ff:ff:ff:ff:ff:ff
altname enp175s0np0
inet 10.18.0.2/24 brd 10.18.0.255 scope global ens4np0
valid_lft forever preferred_lft forever
inet6 fe80::215:4dff:fe16:206a/64 scope link
valid_lft forever preferred_lft forever
45: ens4np1: mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether 00:15:4d:16:20:6b brd ff:ff:ff:ff:ff:ff
altname enp175s0np1
46: eth4: mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 32:a3:d8:8e:61:a8 brd ff:ff:ff:ff:ff:ff
inet6 fe80::30a3:d8ff:fe8e:61a8/64 scope link
valid_lft forever preferred_lft forever
48: e12921368e14_h@if47: mtu 1400 qdisc noqueue master ovs-system state UP group default qlen 1000
link/ether 86:0b:13:97:a8:34 brd ff:ff:ff:ff:ff:ff link-netnsid 0
inet6 fe80::840b:13ff:fe97:a834/64 scope link
valid_lft forever preferred_lft forever
50: 8f49fd46cbd7_h@if49: mtu 1400 qdisc noqueue master ovs-system state UP group default qlen 1000
link/ether 26:17:92:7f:c3:62 brd ff:ff:ff:ff:ff:ff link-netnsid 1
inet6 fe80::2417:92ff:fe7f:c362/64 scope link
valid_lft forever preferred_lft forever
51: ens4v0: mtu 1500 qdisc fq_codel state UP group default qlen 1000
link/ether ca:7b:a7:9b:4d:c7 brd ff:ff:ff:ff:ff:ff
altname enp175s0v0
inet6 fe80::c87b:a7ff:fe9b:4dc7/64 scope link
valid_lft forever preferred_lft forever
52: ens4v1: mtu 1500 qdisc fq_codel state UP group default qlen 1000
link/ether ea:d9:39:76:3c:72 brd ff:ff:ff:ff:ff:ff
altname enp175s0v1
inet6 fe80::e8d9:39ff:fe76:3c72/64 scope link
valid_lft forever preferred_lft forever
53: ens4v2: mtu 1500 qdisc fq_codel state UP group default qlen 1000
link/ether d6:4a:e2:d0:39:c6 brd ff:ff:ff:ff:ff:ff
altname enp175s0v2
inet6 fe80::d44a:e2ff:fed0:39c6/64 scope link
valid_lft forever preferred_lft forever
54: ens4v3: mtu 1500 qdisc fq_codel state UP group default qlen 1000
link/ether f6:50:c1:82:86:3e brd ff:ff:ff:ff:ff:ff
altname enp175s0v3
inet6 fe80::f450:c1ff:fe82:863e/64 scope link
valid_lft forever preferred_lft forever
55: nfp_v0.0: mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether ae:ac:45:bf:8f:d7 brd ff:ff:ff:ff:ff:ff
inet6 fe80::acac:45ff:febf:8fd7/64 scope link
valid_lft forever preferred_lft forever
56: nfp_v0.1: mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 7a:07:8e:22:2c:04 brd ff:ff:ff:ff:ff:ff
inet6 fe80::7807:8eff:fe22:2c04/64 scope link
valid_lft forever preferred_lft forever
57: nfp_v0.2: mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 32:42:eb:73:bb:6f brd ff:ff:ff:ff:ff:ff
inet6 fe80::3042:ebff:fe73:bb6f/64 scope link
valid_lft forever preferred_lft forever
58: nfp_v0.3: mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 8e:b0:54:a3:7a:86 brd ff:ff:ff:ff:ff:ff
inet6 fe80::8cb0:54ff:fea3:7a86/64 scope link
valid_lft forever preferred_lft forever
由ip a的结果可知，compute2服务器上ens4np0网口的状态和ip地址信息均正常。
[root@computer6 ~]# ip a
1: lo: mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: em1: mtu 1500 qdisc mq state UP group default qlen 1000
link/ether 20:04:0f:f2:4a:e8 brd ff:ff:ff:ff:ff:ff
inet 10.8.8.6/24 brd 10.8.8.255 scope global dynamic noprefixroute em1
valid_lft 7000sec preferred_lft 7000sec
inet6 fe80::5395:4226:33be:a549/64 scope link noprefixroute
valid_lft forever preferred_lft forever
3: em2: mtu 1500 qdisc mq state DOWN group default qlen 1000
link/ether 20:04:0f:f2:4a:e9 brd ff:ff:ff:ff:ff:ff
4: em3: mtu 1500 qdisc mq state DOWN group default qlen 1000
link/ether 20:04:0f:f2:4a:ea brd ff:ff:ff:ff:ff:ff
5: em4: mtu 1500 qdisc mq state DOWN group default qlen 1000
link/ether 20:04:0f:f2:4a:eb brd ff:ff:ff:ff:ff:ff
6: enp101s0: mtu 1500 qdisc mq state UP group default qlen 1000
link/ether 62:a5:06:71:9a:f1 brd ff:ff:ff:ff:ff:ff
inet6 fe80::60a5:6ff:fe71:9af1/64 scope link
valid_lft forever preferred_lft forever
7: enp101s0np0: mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether 00:15:4d:16:66:33 brd ff:ff:ff:ff:ff:ff
8: enp101s0np1: mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 00:15:4d:16:66:34 brd ff:ff:ff:ff:ff:ff
inet 10.18.0.6/24 brd 10.18.0.255 scope global enp101s0np1
valid_lft forever preferred_lft forever
inet6 fe80::215:4dff:fe16:6634/64 scope link
valid_lft forever preferred_lft forever
9: eth3: mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 5e:79:ac:37:ba:9c brd ff:ff:ff:ff:ff:ff
inet6 fe80::5c79:acff:fe37:ba9c/64 scope link
valid_lft forever preferred_lft forever
10: p1p1_0: mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether 7e:4a:20:8a:7f:6c brd ff:ff:ff:ff:ff:ff
11: p1p1_1: mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether fe:6c:db:ae:d4:58 brd ff:ff:ff:ff:ff:ff
12: p1p1_2: mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether 5a:0a:6a:3e:57:b2 brd ff:ff:ff:ff:ff:ff
13: p1p1_3: mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether 7e:18:0a:65:82:85 brd ff:ff:ff:ff:ff:ff
14: eth5: mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether 7e:1c:cf:42:16:cb brd ff:ff:ff:ff:ff:ff
15: eth6: mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether 92:f2:db:e7:a8:e1 brd ff:ff:ff:ff:ff:ff
16: eth7: mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether de:be:1c:ea:e6:b1 brd ff:ff:ff:ff:ff:ff
17: eth8: mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether ce:86:a0:0e:dd:99 brd ff:ff:ff:ff:ff:ff
18: docker0: mtu 1500 qdisc noqueue state DOWN group default
link/ether 02:42:39:be:34:40 brd ff:ff:ff:ff:ff:ff
inet 172.17.0.1/16 scope global docker0
valid_lft forever preferred_lft forever
19: virbr0: mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 52:54:00:20:20:25 brd ff:ff:ff:ff:ff:ff
inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
valid_lft forever preferred_lft forever
20: virbr0-nic: mtu 1500 qdisc fq_codel master virbr0 state DOWN group default qlen 1000
link/ether 52:54:00:20:20:25 brd ff:ff:ff:ff:ff:ff
21: vnet0: mtu 1500 qdisc fq_codel master virbr0 state UNKNOWN group default qlen 1000
link/ether fe:54:00:fa:dc:00 brd ff:ff:ff:ff:ff:ff
inet6 fe80::fc54:ff:fefa:dc00/64 scope link
valid_lft forever preferred_lft forever
22: ovs-system: mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether 82:06:fa:8d:b1:2a brd ff:ff:ff:ff:ff:ff
23: mirror0: mtu 1400 qdisc noqueue state UNKNOWN group default qlen 1000
link/ether c2:f5:3b:c9:9f:27 brd ff:ff:ff:ff:ff:ff
inet6 fe80::c0f5:3bff:fec9:9f27/64 scope link
valid_lft forever preferred_lft forever
24: ovn0: mtu 1400 qdisc noqueue state UNKNOWN group default qlen 1000
link/ether 00:00:00:c8:76:7b brd ff:ff:ff:ff:ff:ff
inet 100.64.0.3/16 brd 100.64.255.255 scope global ovn0
valid_lft forever preferred_lft forever
inet6 fe80::200:ff:fec8:767b/64 scope link
valid_lft forever preferred_lft forever
25: genev_sys_6081: mtu 65000 qdisc noqueue master ovs-system state UNKNOWN group default qlen 1000
link/ether 8a:44:7d:eb:aa:c0 brd ff:ff:ff:ff:ff:ff
inet6 fe80::8844:7dff:feeb:aac0/64 scope link
valid_lft forever preferred_lft forever
26: br-int: mtu 1400 qdisc noop state DOWN group default qlen 1000
link/ether c6:4a:8e:92:8d:42 brd ff:ff:ff:ff:ff:ff
36: cf62c26a92f3_h@if35: mtu 1400 qdisc noqueue master ovs-system state UP group default qlen 1000
link/ether a6:5e:d5:bf:22:65 brd ff:ff:ff:ff:ff:ff link-netnsid 1
inet6 fe80::a45e:d5ff:febf:2265/64 scope link
valid_lft forever preferred_lft forever
由ip a的结果可知，computer6服务器上enp101s0np1网口的状态和ip地址信息均正常。
在computer6服务器上通过enp101s0np1网口ping相连的对端网口的地址，情况如下：
[root@computer6 ~]# ping -I enp101s0np1 10.18.0.2
PING 10.18.0.2 (10.18.0.2) from 10.18.0.6 enp101s0np1: 56(84) bytes of data.
^C
--- 10.18.0.2 ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 2076ms
在compute2服务器上通过ens4np0网口ping相连的对端网口的地址，情况如下：
[root@compute2 ~]# ping -I ens4np0 10.18.0.6
PING 10.18.0.6 (10.18.0.6) from 10.18.0.2 ens4np0: 56(84) bytes of data.
^C
--- 10.18.0.6 ping statistics ---
161 packets transmitted, 0 received, 100% packet loss, time 163856ms
pipe 4
根据上述结果可知，在两台服务器上的指定网卡ping都无法ping通对端；接下来以compute2服务器上的现象来进行分析，首先在compute2服务器上进行抓包查看包是否已发送出去，如下：
[root@compute2 ~]# tcpdump -i ens4np0 -nevvv
dropped privs to tcpdump
tcpdump: listening on ens4np0, link-type EN10MB (Ethernet), capture size 262144 bytes
16:29:05.644390 00:15:4d:16:20:6a > Broadcast, ethertype ARP (0x0806), length 42: Ethernet (len 6), IPv4 (len 4), Request who-has 10.18.0.6 tell 10.18.0.2, length 28
16:29:06.704807 00:15:4d:16:20:6a > Broadcast, ethertype ARP (0x0806), length 42: Ethernet (len 6), IPv4 (len 4), Request who-has 10.18.0.6 tell 10.18.0.2, length 28
16:29:07.728773 00:15:4d:16:20:6a > Broadcast, ethertype ARP (0x0806), length 42: Ethernet (len 6), IPv4 (len 4), Request who-has 10.18.0.6 tell 10.18.0.2, length 28
16:29:09.729959 00:15:4d:16:20:6a > Broadcast, ethertype ARP (0x0806), length 42: Ethernet (len 6), IPv4 (len 4), Request who-has 10.18.0.6 tell 10.18.0.2, length 28
^C
根据抓包报文可知，compute2服务器的网络协议栈已经将arp请求报文发出，接下来查看对端服务器是否收到arp请求报文，如下：
[root@computer6 ~]# tcpdump -i enp101s0np1 -e -n
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on enp101s0np1, link-type EN10MB (Ethernet), capture size 262144 bytes
15:30:00.449732 0c:29:ef:bf:b1:a3 > 01:80:c2:00:00:0e, ethertype LLDP (0x88cc), length 414: LLDP, length 400: dell-switch
15:30:30.451960 0c:29:ef:bf:b1:a3 > 01:80:c2:00:00:0e, ethertype LLDP (0x88cc), length 396: LLDP, length 382: dell-switch
15:31:00.454307 0c:29:ef:bf:b1:a3 > 01:80:c2:00:00:0e, ethertype LLDP (0x88cc), length 414: LLDP, length 400: dell-switch
^C
根据上述抓包结果可知，computer6服务器上未收到对端服务器的arp请求报文。因此推测可能是交换机出现了问题，因此，接下来需要查看交换机上端口是否正常，是否能正常转发arp报文。
dell-switch# show interface status
--------------------------------------------------------------------------------------------------
Port Description Status Speed Duplex Mode Vlan Tagged-Vlans
--------------------------------------------------------------------------------------------------
Eth 1/1/1 down 0 full T 93 103,105
Eth 1/1/2 down 0 full T 93 103,105
Eth 1/1/3 up 25G full A 66 -
Eth 1/1/4 down 0 full A 66 -
Eth 1/1/5:1 down 0 full A 5 -
Eth 1/1/6:1 down 0 full A 5 -
Eth 1/1/7:1 down 0 full A 5 -
Eth 1/1/8:1 down 0 full A 5 -
Eth 1/1/9:1 down 0 full A 100 -
Eth 1/1/10:1 up 10G full A 66 -
Eth 1/1/11:1 down 0 full A 100 -
Eth 1/1/12:1 down 0 full A 66 -
Eth 1/1/13 down 0 full A 5 -
Eth 1/1/14 down 0 full A 5 -
Eth 1/1/15 down 0 full A 5 -
--------------------------------------------------------------------------------------------------
由上可知，交换机连接的服务器的两个接口状态均是up的，并且同处于一个vlan 66中.接下来再查看一下mac地址转发表是否正常，如下：
dell-switch# show mac address-table
VlanId Mac Address Type Interface
66 22:15:4d:16:66:34 dynamic ethernet1/1/3
dell-switch#
通过mac地址转发表可知，交换机只学习到了和ethernet1/1接口连接的网卡的mac地址，而未学习到与ethernet1/1/10:1接口连接的网卡的mac地址。至于原因，不得而知，此时就需要搞明白为什么交换机没有学习到与ethernet1/1/10:1接口连接的网卡的mac地址。因此决定在交换机上进行抓包，从而确定交换机是否收到网络报文。
通常来讲，交换机上抓包，网络上的博文一般都会告诉你通过镜像抓包的方式，但是简单看了一下镜像抓包的博文，看起来就很麻烦，而且我所使用的Dell交换机在网络上资料极少，基本搜不到详细的镜像抓包的指导方法。此时，便抱着试试的心态，求助其他大佬，大佬很谦虚，告诉我他已经很久没有搞过交换机了，但是依然很热心的帮我看了一下，一手操作，简直秀翻我，接下来一起欣赏他的骚操作。
dell-switch# show interface ethernet 1/1/10:1
Ethernet 1/1/10:1 is up, line protocol is up
Hardware is Eth, address is 0c:29:ef:bf:b1:aa
Current address is 0c:29:ef:bf:b1:aa
Pluggable media present, SFP28 type is SFP28 25GBASE-SR
Wavelength is 850
Receive power reading is -1.988708 dBm
Interface index is 23
Internet address is not set
Mode of IPv4 Address Assignment: not set
Interface IPv6 oper status: Disabled
MTU 1532 bytes, IP MTU 1500 bytes
LineSpeed 10G, Auto-Negotiation off
Flowcontrol rx off tx off
ARP type: ARPA, ARP Timeout: 60
Last clearing of "show interface" counters: 7 weeks 2 days 08:41:05
Queuing strategy: fifo
Input statistics:
178525367 packets, 11432189964 octets
178454818 64-byte pkts, 14780 over 64-byte pkts, 51913 over 127-byte pkts
3855 over 255-byte pkts, 0 over 511-byte pkts, 1 over 1023-byte pkts
66 Multicasts, 11799 Broadcasts, 70959 Unicasts
0 runts, 4 giants, 178442543 throttles
0 CRC, 0 overrun, 4 discarded
Output statistics:
202637 packets, 102558633 octets
75004 64-byte pkts, 16167 over 64-byte pkts, 29153 over 127-byte pkts
22923 over 255-byte pkts, 7004 over 511-byte pkts, 52386 over 1023-byte pkts
17650 Multicasts, 57789 Broadcasts, 127198 Unicasts
0 throttles, 0 discarded, 0 Collisions, wred drops
Rate Info(interval seconds):
Input 0 Mbits/sec, 454 packets/sec, 0% of line rate
Output 0 Mbits/sec, 1 packets/sec, 0% of line rate
Time since last interface status change: 00:22:59
dell-switch# show interface ethernet 1/1/10:1
Ethernet 1/1/10:1 is up, line protocol is up
Hardware is Eth, address is 0c:29:ef:bf:b1:aa
Current address is 0c:29:ef:bf:b1:aa
Pluggable media present, SFP28 type is SFP28 25GBASE-SR
Wavelength is 850
Receive power reading is -1.991455 dBm
Interface index is 23
Internet address is not set
Mode of IPv4 Address Assignment: not set
Interface IPv6 oper status: Disabled
MTU 1532 bytes, IP MTU 1500 bytes
LineSpeed 10G, Auto-Negotiation off
Flowcontrol rx off tx off
ARP type: ARPA, ARP Timeout: 60
Last clearing of "show interface" counters: 7 weeks 2 days 08:41:54
Queuing strategy: fifo
Input statistics:
178548095 packets, 11433644556 octets
178477546 64-byte pkts, 14780 over 64-byte pkts, 51913 over 127-byte pkts
3855 over 255-byte pkts, 0 over 511-byte pkts, 1 over 1023-byte pkts
66 Multicasts, 11799 Broadcasts, 70959 Unicasts
0 runts, 4 giants, 178465271 throttles
0 CRC, 0 overrun, 4 discarded
Output statistics:
202688 packets, 102562941 octets
75052 64-byte pkts, 16167 over 64-byte pkts, 29153 over 127-byte pkts
22926 over 255-byte pkts, 7004 over 511-byte pkts, 52386 over 1023-byte pkts
17653 Multicasts, 57837 Broadcasts, 127198 Unicasts
0 throttles, 0 discarded, 0 Collisions, wred drops
Rate Info(interval seconds):
Input 0 Mbits/sec, 378 packets/sec, 0% of line rate
Output 0 Mbits/sec, 0 packets/sec, 0% of line rate
Time since last interface status change: 00:23:48
dell-switch# show interface ethernet 1/1/10:1
Ethernet 1/1/10:1 is up, line protocol is up
Hardware is Eth, address is 0c:29:ef:bf:b1:aa
Current address is 0c:29:ef:bf:b1:aa
Pluggable media present, SFP28 type is SFP28 25GBASE-SR
Wavelength is 850
Receive power reading is -1.991455 dBm
Interface index is 23
Internet address is not set
Mode of IPv4 Address Assignment: not set
Interface IPv6 oper status: Disabled
MTU 1532 bytes, IP MTU 1500 bytes
LineSpeed 10G, Auto-Negotiation off
Flowcontrol rx off tx off
ARP type: ARPA, ARP Timeout: 60
Last clearing of "show interface" counters: 7 weeks 2 days 08:43:17
Queuing strategy: fifo
Input statistics:
178584469 packets, 11435972492 octets
178513920 64-byte pkts, 14780 over 64-byte pkts, 51913 over 127-byte pkts
3855 over 255-byte pkts, 0 over 511-byte pkts, 1 over 1023-byte pkts
66 Multicasts, 11799 Broadcasts, 70959 Unicasts
0 runts, 4 giants, 178501645 throttles
0 CRC, 0 overrun, 4 discarded
Output statistics:
202770 packets, 102569233 octets
75131 64-byte pkts, 16167 over 64-byte pkts, 29153 over 127-byte pkts
22929 over 255-byte pkts, 7004 over 511-byte pkts, 52386 over 1023-byte pkts
17656 Multicasts, 57916 Broadcasts, 127198 Unicasts
0 throttles, 0 discarded, 0 Collisions, wred drops
Rate Info(interval seconds):
Input 0 Mbits/sec, 454 packets/sec, 0% of line rate
Output 0 Mbits/sec, 1 packets/sec, 0% of line rate
Time since last interface status change: 00:25:11
因为ethernet1/1/10:1接口未学习到mac地址，因此多次查看该接口的状态，发现入向throttles统计的值一直在不停的增加，该统计值的意思是“节流或抑制”；交换机流量过载会触发该节流操作，其数值表示端口上的接收器被禁用的次数，持续的查找设备的MAC地址的过载流量导致其发生，短时间内无法接收任何新的数据包，因此决定抓包确认一下。
大佬告诉我交换机有一种Linux模式，可以切换到该模式下，直接使用tcpdump进行端口抓包。听到这我顿时眼前一亮，竟然还有这样的骚(黑)操(科)作(技)！只见他直接就在交换机上切换到Linux模式，开始一系列操作：
#在交换机上使用ifconfig命令查看两个接口所属vlan66所对应的网桥，原来交换机上是通过网桥的方式实现的vlan
dell-switch# system "ifconfig"
bo1: flags=5123 mtu 1568
inet6 fe80::e29:efff:febf:b1ba prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:ba txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 5 overruns 0 carrier 0 collisions 0
bo2: flags=5123 mtu 1500
inet 6.6.6.10 netmask 255.255.255.0 broadcast 6.6.6.255
inet6 fe80::e29:efff:febf:b1bb prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:bb txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 3 overruns 0 carrier 0 collisions 0
bo3: flags=5123 mtu 1568
inet6 fe80::e29:efff:febf:b1bc prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:bc txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 4 overruns 0 carrier 0 collisions 0
bo4: flags=5123 mtu 1500
inet6 fe80::e29:efff:febf:b1bd prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:bd txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 2 overruns 0 carrier 0 collisions 0
bo5: flags=5123 mtu 1500
inet 5.5.5.10 netmask 255.255.255.0 broadcast 5.5.5.255
inet6 fe80::e29:efff:febf:b1be prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:be txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 2 overruns 0 carrier 0 collisions 0
bo1.555: flags=4099 mtu 1500
ether 0c:29:ef:bf:b1:ba txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
bo3.888: flags=4099 mtu 1500
ether 0c:29:ef:bf:b1:bc txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br1: flags=4355 mtu 1500
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br2: flags=4355 mtu 1500
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br3: flags=4355 mtu 1500
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br4: flags=4355 mtu 1500
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br5: flags=4355 mtu 1500
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 590 bytes 38612 (37.7 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1205 bytes 110594 (108.0 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br66: flags=4419 mtu 1500
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 154750 bytes 7761460 (7.4 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 5146 bytes 459568 (448.7 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br93: flags=4355 mtu 1500
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 7 bytes 452 (452.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 24 bytes 2728 (2.6 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br100: flags=4355 mtu 1500
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 113 bytes 7136 (6.9 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 78 bytes 7116 (6.9 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br103: flags=4355 mtu 9184
inet 12.8.8.200 netmask 255.255.255.0 broadcast 12.8.8.255
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 18 bytes 2148 (2.0 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br105: flags=4355 mtu 1500
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 19 bytes 2278 (2.2 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br111: flags=4355 mtu 1500
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br112: flags=4355 mtu 1500
inet 12.12.12.10 netmask 255.255.255.0 broadcast 12.12.12.255
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br123: flags=4355 mtu 1500
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br135: flags=4355 mtu 1500
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br222: flags=4355 mtu 1500
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br246: flags=4355 mtu 1500
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br555: flags=4355 mtu 1500
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br888: flags=4355 mtu 1500
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br3055: flags=4355 mtu 1500
inet6 fe80::e29:efff:febf:b1d1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
e101-001-0: flags=4099 mtu 9184
inet6 fe80::e29:efff:febf:b1a1 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:a1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
e101-001-0.103: flags=4099 mtu 9184
ether 0c:29:ef:bf:b1:a1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
e101-001-0.105: flags=4099 mtu 1500
ether 0c:29:ef:bf:b1:a1 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
e101-002-0: flags=4099 mtu 9184
inet6 fe80::e29:efff:febf:b1a2 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:a2 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
e101-002-0.103: flags=4099 mtu 9184
ether 0c:29:ef:bf:b1:a2 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
e101-002-0.105: flags=4099 mtu 1500
ether 0c:29:ef:bf:b1:a2 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
e101-003-0: flags=4163 mtu 1500
inet6 fe80::e29:efff:febf:b1a3 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:a3 txqueuelen 1000 (Ethernet)
RX packets 100517 bytes 6448390 (6.1 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 41414 bytes 16157928 (15.4 MiB)
TX errors 0 dropped 82 overruns 0 carrier 0 collisions 0
e101-004-0: flags=4099 mtu 1500
inet6 fe80::e29:efff:febf:b1a4 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:a4 txqueuelen 1000 (Ethernet)
RX packets 51163 bytes 4662460 (4.4 MiB)
RX errors 0 dropped 8756 overruns 0 frame 0
TX packets 19779 bytes 7863844 (7.4 MiB)
TX errors 0 dropped 2 overruns 0 carrier 0 collisions 0
e101-005-1: flags=4099 mtu 1500
inet6 fe80::c0e3:b6ff:fe13:ef15 prefixlen 64 scopeid 0x20
inet6 fe80::e29:efff:febf:b1a5 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:a5 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
e101-006-1: flags=4099 mtu 1500
inet6 fe80::48b1:c4ff:fe53:f38b prefixlen 64 scopeid 0x20
inet6 fe80::e29:efff:febf:b1a6 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:a6 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
e101-007-1: flags=4099 mtu 1500
inet6 fe80::e29:efff:febf:b1a7 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:a7 txqueuelen 1000 (Ethernet)
RX packets 783 bytes 112048 (109.4 KiB)
RX errors 0 dropped 686 overruns 0 frame 0
TX packets 568 bytes 204976 (200.1 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
e101-008-1: flags=4099 mtu 1500
inet6 fe80::e29:efff:febf:b1a8 prefixlen 64 scopeid 0x20
inet6 fe80::d8af:76ff:feaf:18aa prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:a8 txqueuelen 1000 (Ethernet)
RX packets 21218 bytes 3182748 (3.0 MiB)
RX errors 0 dropped 20757 overruns 0 frame 0
TX packets 11030 bytes 4292132 (4.0 MiB)
TX errors 0 dropped 1 overruns 0 carrier 0 collisions 0
e101-009-1: flags=4099 mtu 1500
inet6 fe80::e29:efff:febf:b1a9 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:a9 txqueuelen 1000 (Ethernet)
RX packets 319 bytes 44574 (43.5 KiB)
RX errors 0 dropped 274 overruns 0 frame 0
TX packets 223 bytes 71226 (69.5 KiB)
TX errors 0 dropped 10 overruns 0 carrier 0 collisions 0
e101-010-1: flags=4163 mtu 1500
inet6 fe80::e29:efff:febf:b1aa prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:aa txqueuelen 1000 (Ethernet)
RX packets 12276 bytes 785716 (767.3 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 16846 bytes 6830524 (6.5 MiB)
TX errors 0 dropped 18 overruns 0 carrier 0 collisions 0
e101-011-1: flags=4099 mtu 1500
inet6 fe80::e29:efff:febf:b1ab prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:ab txqueuelen 1000 (Ethernet)
RX packets 5616 bytes 827516 (808.1 KiB)
RX errors 0 dropped 5330 overruns 0 frame 0
TX packets 2896 bytes 1128536 (1.0 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
e101-012-1: flags=4099 mtu 1500
inet6 fe80::e29:efff:febf:b1ac prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:ac txqueuelen 1000 (Ethernet)
RX packets 2973 bytes 196128 (191.5 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 13306 bytes 5271746 (5.0 MiB)
TX errors 0 dropped 1 overruns 0 carrier 0 collisions 0
e101-013-0: flags=4099 mtu 1500
inet6 fe80::e29:efff:febf:b1ad prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:ad txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
e101-014-0: flags=4099 mtu 1500
inet6 fe80::e29:efff:febf:b1ae prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:ae txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
e101-015-0: flags=4099 mtu 1500
inet6 fe80::e29:efff:febf:b1af prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:af txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
eth0: flags=4163 mtu 1468
inet 10.8.8.49 netmask 255.255.255.0 broadcast 10.8.8.255
inet6 fe80::e29:efff:febf:b1a0 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:a0 txqueuelen 1000 (Ethernet)
RX packets 2131062 bytes 191899479 (183.0 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1980745 bytes 171880577 (163.9 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
device memory 0xdfe00000-dfe7ffff
lo: flags=73 mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10
inet6 fe80::200:ff:fe00:0 prefixlen 64 scopeid 0x20
loop txqueuelen 1 (Local Loopback)
RX packets 1108153681 bytes 103323200462 (96.2 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1108153681 bytes 103323200462 (96.2 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
vn123: flags=4355 mtu 1500
inet6 fe80::e29:efff:febf:b1d3 prefixlen 64 scopeid 0x20
ether 0c:29:ef:bf:b1:d3 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
#直接使用brctl网桥指令查看网桥上的接口
dell-switch# system "brctl show br66"
bridge name bridge id STP enabled interfaces
br66 8000.0c29efbfb1d1 no e101-003-0
e101-004-0
e101-010-1
e101-012-1
#使用brctl help指令查看brctl的其他指令如何使用
dell-switch# system "brctl help"
never heard of command [help]
Usage: brctl [commands]
commands:
addbr add bridge
delbr delete bridge
addif add interface to bridge
delif delete interface from bridge
hairpin {on|off} turn hairpin on/off
setageing
STP（Spanning Tree Protocol）是一个用于局域网中消除环路的协议，它的标准是IEEE 802.1D。STP通过将部分冗余链路强制为阻塞状态，其他链路处于转发状态，将环形网络结构修剪成无环路的树形网络结构，可实现消除环路。当处于转发状态的链路不可用时，STP重新配置网络，并激活合适的备用链路状态，恢复恢复网络连通性。在一个复杂的网络环境中，由于冗余备份的需要，网络设计者都倾向于在设备之间部署多条物理链路，其中一条作主用链路，其他链路作备份，偶然或必然中都会导致环路产生。环路会产生广播风暴，最终导致整个网络资源被耗尽，网络瘫痪不可用。环路还会引起
MAC地址表震荡导致MAC地址表项被破坏。
STP技术可以有效的解决环路问题，将彼此交互信息发现网络中的环路，将部分冗余链路强制为阻塞状态，其他链路处于转发状态。最终将环形网络结构修剪成无环路的树形网络结构，从而防止报文在环形网络中不断增生和无限循环，避免设备由于重复接收相同的报文造成处理能力下降。
由show interface status指令结果可知,Eth1/1/3接口连接computer6服务器上enp101s0np1网口，由brctl show br66指令可知，br66桥上的e101-003-0接口即对应交换机的Eth1/1/3接口,因此在e101-003-0接口抓包，即就是在Eth1/1/3接口抓包。如下：
dell-switch# system "sudo tcpdump -i e101-003-0"
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on e101-003-0, link-type EN10MB (Ethernet), capture size 262144 bytes
16:28:47.900070 ARP, Request who-has 10.18.0.2 tell 10.18.0.6, length 50
16:28:48.948548 ARP, Request who-has 10.18.0.2 tell 10.18.0.6, length 50
16:28:49.972517 ARP, Request who-has 10.18.0.2 tell 10.18.0.6, length 50
16:28:50.996668 ARP, Request who-has 10.18.0.2 tell 10.18.0.6, length 50
16:28:52.020531 ARP, Request who-has 10.18.0.2 tell 10.18.0.6, length 50
16:28:53.044518 ARP, Request who-has 10.18.0.2 tell 10.18.0.6, length 50
^C
由上述结果，可知，交换机上能够收到computer6服务器上enp101s0np1网口发来的arp请求包，所以交换机上的mac转发表有enp101s0np1网口的mac地址；让我们再在e101-010-1 接口抓包，也就是在Eth1/1/10:1 接口抓包，如下：
dell-switch# system "sudo tcpdump -i e101-010-1"
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on e101-010-1, link-type EN10MB (Ethernet), capture size 262144 bytes
^C
0 packets captured
0 packets received by filter
0 packets dropped by kernel
%Error: while executing(system).Ret val[0].
dell-switch#
由上述结果可知，交换机该接口没有网络报文，结合前面throttles的数值的不断增加，可知该接口因持续的收到查找设备MAC地址的报文，导致该接口输入队列持续过载，从而触发节流操作，无法再接收新的报文。因此在交换机该接口无法再抓到任何报文，compute2服务器上ens4np0网口无法抓到对端发来的arp请求报文也印证了这一点。
为什么会导致该接口输入队列持续过载？因为持续的收到查找设备MAC地址的报文。为什么会持续的收到找设备MAC地址的报文？因此推测可能是连接该交换机端口的设备异常，导致无法响应查找MAC地址的报文。因此，开始检查和该交换机端口连接的网络设备是否异常，如下：
[root@compute2 ~]# ethtool -S ens4np0
NIC statistics:
mac.rx_octets: 2441345
mac.rx_frame_too_long_errors: 0
mac.rx_range_length_errors: 0
mac.rx_vlan_received_ok: 0
mac.rx_errors: 0
mac.rx_broadcast_pkts: 16200
mac.rx_drop_events: 0
mac.rx_alignment_errors: 0
mac.rx_pause_mac_ctrl_frames: 0
mac.rx_frames_received_ok: 19943
mac.rx_frame_check_sequence_err: 0
mac.rx_unicast_pkts: 55
mac.rx_multicast_pkts: 3688
mac.rx_pkts: 19943
mac.rx_undersize_pkts: 0
mac.rx_pkts_64_octets: 16216
mac.rx_pkts_65_to_127_octets: 427
mac.rx_pkts_128_to_255_octets: 29
mac.rx_pkts_256_to_511_octets: 3270
mac.rx_pkts_512_to_1023_octets: 0
mac.rx_pkts_1024_to_1518_octets: 1
mac.rx_pkts_1519_to_max_octets: 0
mac.rx_jabbers: 0
mac.rx_fragments: 0
mac.rx_oversize_pkts: 0
mac.rx_pause_frames_class0: 0
mac.rx_pause_frames_class1: 0
mac.rx_pause_frames_class2: 0
mac.rx_pause_frames_class3: 0
mac.rx_pause_frames_class4: 0
mac.rx_pause_frames_class5: 0
mac.rx_pause_frames_class6: 0
mac.rx_pause_frames_class7: 0
mac.rx_mac_ctrl_frames_received: 0
mac.rx_mac_head_drop: 19252
mac.tx_queue_drop: 0
mac.tx_octets: 2188771300
mac.tx_vlan_transmitted_ok: 0
mac.tx_errors: 1
mac.tx_broadcast_pkts: 7
mac.tx_pause_mac_ctrl_frames: 34199164
mac.tx_frames_transmitted_ok: 34199209
mac.tx_unicast_pkts: 37
mac.tx_multicast_pkts: 1
mac.tx_pkts_64_octets: 34199172
mac.tx_pkts_65_to_127_octets: 2
mac.tx_pkts_128_to_255_octets: 23
mac.tx_pkts_256_to_511_octets: 12
mac.tx_pkts_512_to_1023_octets: 0
mac.tx_pkts_1024_to_1518_octets: 0
mac.tx_pkts_1519_to_max_octets: 1
mac.tx_pause_frames_class0: 0
mac.tx_pause_frames_class1: 0
mac.tx_pause_frames_class2: 0
mac.tx_pause_frames_class3: 0
mac.tx_pause_frames_class4: 0
mac.tx_pause_frames_class5: 0
mac.tx_pause_frames_class6: 0
mac.tx_pause_frames_class7: 0
通过ethtool工具查看该网络设备的统计信息，rx_mac_head_drop统计值明显异常，可知网卡无法处理mac报文头从而丢掉。再查看dmesg信息，如下：
[root@compute2 ~]# dmesg | tail
[44688.426342] nfp 0000:af:00.0: nfp: Reading media link modes not supported. Please update flash
[44688.630940] nfp 0000:af:00.0 ens4: TX watchdog timeout on ring: 4
[44694.774418] nfp 0000:af:00.0 ens4: TX watchdog timeout on ring: 4
[44700.405916] nfp 0000:af:00.0 ens4: TX watchdog timeout on ring: 4
[44705.525421] nfp 0000:af:00.0 ens4: TX watchdog timeout on ring: 4
[44710.644983] nfp 0000:af:00.0 ens4: TX watchdog timeout on ring: 4
[44716.789408] nfp 0000:af:00.0 ens4: TX watchdog timeout on ring: 4
[44722.419914] nfp 0000:af:00.0 ens4: TX watchdog timeout on ring: 4
[44727.539463] nfp 0000:af:00.0 ens4: TX watchdog timeout on ring: 4
[44732.659012] nfp 0000:af:00.0 ens4: TX watchdog timeout on ring: 4
到此，终于知道问题所在了，原来是网卡的固件和BSP异常，使用23.04版本更新固件和BSP版本；加载成功之后，重启主机，再次配置网络信息后，网络终于通了，如下：
[root@compute2 ~]# ping -I ens4np0 10.18.0.6
PING 10.18.0.6 (10.18.0.16) from 10.18.0.2 ens4np0: 56(84) bytes of data.
64 bytes from 10.18.0.6: icmp_seq=1 ttl=64 time=0.293 ms
64 bytes from 10.18.0.6: icmp_seq=2 ttl=64 time=0.312 ms
^C
问题终于解决了，简直太不容易了，这个问题困扰了小编好久，没想到被大佬三下五除二就解决了，大佬不愧是大佬，就是强。
查看交换机上的MAC转发表，如下：
dell-switch# show mac address-table
VlanId Mac Address Type Interface
66 00:15:4d:16:20:6a dynamic ethernet1/1/10:1
66 00:15:4d:16:66:34 dynamic ethernet1/1/3
交换机也能正常学习到mac了。
本文通过一个简单的二层流量不通的小例子，讲解流量不通的排障方法，包括服务器网卡抓包、交换机接口抓包等操作。其中，交换机通过tcpdump工具抓包不得不说是一个黑科技，第一次知道交换机还可以这样玩，小编一直以为交换机抓包只能通过端口镜像操作，有点刷新了小编对交换机的认知。我相信其他厂家的交换机应该也有这种神操作，方法未必完全一样，但是通过tcpdump抓包的神迹应该都具备，大家感兴趣的可以去试一下。
