我的两台 Dell R610 服务器上的 NIC 速度（LAN 和 WAN）都非常慢。我还有多个具有相同规格的其他 R610，连接到同一个 Cisco 3750 交换机，它们都运行正常。我进行了大量故障排除，但仍然无法解决问题。我的 Observium 在我的网络上没有显示峰值，在任何其他服务器上也没有显示可能导致任何类型瓶颈的大量流量。
尝试更换 NIC 卡
尝试在服务器 NIC 和 Cisco 交换机上使用多个端口
尝试全新安装 Centos 6.8 和 Centos 7
通过 Dell Repo 升级 NIC 驱动程序（专用于 Linux）
更换 Cat5 电缆
重新启动服务器
在服务器和 Cisco 交换机上启用 GigE，全双工
尝试使用 Google 解析器和数据中心解析器
[root@localhost ~]# wget -O /dev/null http://cachefly.cachefly.net/100mb.test
--2016-07-05 13:32:59-- http://cachefly.cachefly.net/100mb.test
Resolving cachefly.cachefly.net (cachefly.cachefly.net)... 205.234.175.175
Connecting to cachefly.cachefly.net (cachefly.cachefly.net)|205.234.175.175|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 104857600 (100M) [application/octet-stream]
Saving to: ‘/dev/null’
0% [ ] 162,475 24.4KB/s eta 73m 24s
[root@localhost ~]# ethtool -i em1
driver: bnx2
version: 2.2.6
firmware-version: 7.12.19 bc 7.10.0 NCSI 2.0.13
bus-info: 0000:01:00.0
supports-statistics: yes
supports-test: yes
supports-eeprom-access: yes
supports-register-dump: yes
supports-priv-flags: no
[root@localhost ~]# ethtool em1
Settings for em1:
Supported ports: [ TP ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Supported pause frame use: No
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Advertised pause frame use: No
Advertised auto-negotiation: Yes
Speed: 1000Mb/s
Duplex: Full
Port: Twisted Pair
PHYAD: 1
Transceiver: internal
Auto-negotiation: on
MDI-X: off
Supports Wake-on: g
Wake-on: d
Link detected: yes
[root@localhost ~]# lspci -v | grep Ethernet -A 1
01:00.0 Ethernet controller: Broadcom Corporation NetXtreme II BCM5709 Gigabit Ethernet (rev 20)
Subsystem: Dell PowerEdge R610 BCM5709 Gigabit Ethernet
Flags: bus master, fast devsel, latency 0, IRQ 36
--
01:00.1 Ethernet controller: Broadcom Corporation NetXtreme II BCM5709 Gigabit Ethernet (rev 20)
Subsystem: Dell PowerEdge R610 BCM5709 Gigabit Ethernet
Flags: bus master, fast devsel, latency 0, IRQ 48
--
02:00.0 Ethernet controller: Broadcom Corporation NetXtreme II BCM5709 Gigabit Ethernet (rev 20)
Subsystem: Dell PowerEdge R610 BCM5709 Gigabit Ethernet
Flags: bus master, fast devsel, latency 0, IRQ 32
--
02:00.1 Ethernet controller: Broadcom Corporation NetXtreme II BCM5709 Gigabit Ethernet (rev 20)
Subsystem: Dell PowerEdge R610 BCM5709 Gigabit Ethernet
Flags: bus master, fast devsel, latency 0, IRQ 42
从 Cisco 交换机来看，没有错误：
Cisco3750#show interface Gi1/0/13
GigabitEthernet1/0/13 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is 001f.6c8a.938d (bia 001f.6c8a.938d)
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s, media type is 10/100/1000BaseTX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 1000 bits/sec, 1 packets/sec
23470 packets input, 5854358 bytes, 0 no buffer
Received 12 broadcasts (5 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 5 multicast, 0 pause input
0 input packets with dribble condition detected
240225 packets output, 19478755 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out