系统突然之间就断网了，在messge日志里看到：
Jun 29 14:23:52 localhost kernel: WARNING: at net/sched/sch_generic.c:265 dev_watchdog+0x26b/0x280() (Not tainted)
Jun 29 14:23:52 localhost kernel: Hardware name: X9SCL/X9SCM
Jun 29 14:23:52 localhost kernel: NETDEV WATCHDOG: eth1 (e1000e): transmit queue 0 timed out
Jun 29 14:23:52 localhost kernel: Modules linked in: fuse ip6table_filter ip6_tables ebtable_nat ebtables ipt_REJECT xt_CHECKSUM 8021q garp cpufreq_ondemand acpi_cpufreq freq_table mperf bridge stp llc ipv6 vhost_net macvtap macvlan tun kvm_intel kvm ipmi_si ipmi_msghandler microcode iTCO_wdt iTCO_vendor_support sg joydev serio_raw i2c_i801 i2c_core lpc_ich mfd_core shpchp e1000e ptp pps_core ext4 jbd2 mbcache sd_mod crc_t10dif ahci video output dm_mirror dm_region_hash dm_log dm_mod [last unloaded: nf_conntrack]
Jun 29 14:23:52 localhost kernel: Pid: 0, comm: swapper Not tainted 2.6.32-642.el6.x86_64 #1
Jun 29 14:23:52 localhost kernel: Call Trace:
Jun 29 14:23:52 localhost kernel: <IRQ> [<ffffffff8107c911>] ? warn_slowpath_common+0x91/0xe0
Jun 29 14:23:52 localhost kernel: [<ffffffff8107ca16>] ? warn_slowpath_fmt+0x46/0x60
Jun 29 14:23:52 localhost kernel: [<ffffffff8149a99b>] ? dev_watchdog+0x26b/0x280
Jun 29 14:23:52 localhost kernel: [<ffffffff8106864c>] ? scheduler_tick+0xdc/0x2b0
Jun 29 14:23:52 localhost kernel: [<ffffffff8149a730>] ? dev_watchdog+0x0/0x280
Jun 29 14:23:52 localhost kernel: [<ffffffff8108fb27>] ? run_timer_softirq+0x197/0x340
Jun 29 14:23:52 localhost kernel: [<ffffffff8108f386>] ? update_process_times+0x76/0x90
Jun 29 14:23:52 localhost kernel: [<ffffffff81085495>] ? __do_softirq+0xe5/0x230
Jun 29 14:23:52 localhost kernel: [<ffffffff8100c38c>] ? call_softirq+0x1c/0x30
Jun 29 14:23:52 localhost kernel: [<ffffffff8100fca5>] ? do_softirq+0x65/0xa0
Jun 29 14:23:52 localhost kernel: [<ffffffff81085325>] ? irq_exit+0x85/0x90
Jun 29 14:23:52 localhost kernel: [<ffffffff8155185a>] ? smp_apic_timer_interrupt+0x4a/0x60
Jun 29 14:23:52 localhost kernel: [<ffffffff8100bc13>] ? apic_timer_interrupt+0x13/0x20
Jun 29 14:23:52 localhost kernel: <EOI> [<ffffffff812facfe>] ? intel_idle+0xfe/0x1b0
Jun 29 14:23:52 localhost kernel: [<ffffffff812face1>] ? intel_idle+0xe1/0x1b0
Jun 29 14:23:52 localhost kernel: [<ffffffff81014ac9>] ? sched_clock+0x9/0x10
Jun 29 14:23:52 localhost kernel: [<ffffffff810adfcd>] ? sched_clock_cpu+0xcd/0x110
Jun 29 14:23:52 localhost kernel: [<ffffffff8144093a>] ? cpuidle_idle_call+0x7a/0xe0
Jun 29 14:23:52 localhost kernel: [<ffffffff81009fe6>] ? cpu_idle+0xb6/0x110
Jun 29 14:23:52 localhost kernel: [<ffffffff81540ab9>] ? start_secondary+0x2c0/0x316
Jun 29 14:23:52 localhost kernel: ---[ end trace 604aa4cd80c5efdb ]---
Jun 29 14:23:52 localhost kernel: e1000e 0000:02:00.0: eth1: Reset adapter unexpectedly
Jun 29 14:23:52 localhost kernel: br1: port 1(eth1) entering disabled state
Jun 29 14:23:52 localhost NetworkManager[2281]: <info> (eth1): carrier now OFF (device state 3)
Jun 29 14:23:52 localhost NetworkManager[2281]: <info> (eth1): device state change: disconnected -> unavailable (reason 'carrier-chagned') [3 2 40]
Jun 29 14:23:52 localhost NetworkManager[2281]: <info> (eth1): deactivating device (reason 'carrier-chagned') [40]
Jun 29 14:23:52 localhost kernel: e1000e 0000:02:00.0: eth1: Timesync Tx Control register not set as expected

通过网上搜素，发现是网卡驱动出现了问题，网上的解决方法是更新网卡驱动。由于没有亲自测试网卡驱动，本次就通过“yum -y update”更新系统，更新网卡驱动可解决此问题。

查看系统版本
[root@localhost ~]# uname -a
Linux localhost.localdomain 2.6.32-431.el6.x86_64 #1 SMP Fri Nov 22 03:15:09 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
[root@localhost ~]# cat /proc/version
Linux version 2.6.32-431.el6.x86_64 (mockbuild@c6b8.bsys.dev.centos.org) (gcc version 4.4.7 20120313 (Red Hat 4.4.7-4) (GCC) ) #1 SMP Fri Nov 22 03:15:09 UTC 2013
[root@localhost ~]# lsb_release -a
LSB Version: :base-4.0-amd64:base-4.0-noarch:core-4.0-amd64:core-4.0-noarch:graphics-4.0-amd64:graphics-4.0-noarch:printing-4.0-amd64:printing-4.0-noarch
Distributor ID: CentOS
Description: CentOS release 6.5 (Final)
Release: 6.5
Codename: Final
查看网卡驱动
[root@localhost ~]# modinfo bnx2
filename: /lib/modules/2.6.32-431.el6.x86_64/kernel/drivers/net/bnx2.ko
firmware: bnx2/bnx2-rv2p-09ax-6.0.17.fw
firmware: bnx2/bnx2-rv2p-09-6.0.17.fw
firmware: bnx2/bnx2-mips-09-6.2.1b.fw
firmware: bnx2/bnx2-rv2p-06-6.0.15.fw
firmware: bnx2/bnx2-mips-06-6.2.3.fw
version: 2.2.3
license: GPL
description: Broadcom NetXtreme II BCM5706/5708/5709/5716 Driver
author: Michael Chan <mchan@broadcom.com>
srcversion: 17D4A614D14049C677860EC
alias: pci:v000014E4d0000163Csvsdbcsci
alias: pci:v000014E4d0000163Bsvsdbcsci
alias: pci:v000014E4d0000163Asvsdbcsci
alias: pci:v000014E4d00001639svsdbcsci
alias: pci:v000014E4d000016ACsvsdbcsci
alias: pci:v000014E4d000016AAsvsdbcsci
alias: pci:v000014E4d000016AAsv0000103Csd00003102bcsci
alias: pci:v000014E4d0000164Csvsdbcsci
alias: pci:v000014E4d0000164Asvsdbcsci
alias: pci:v000014E4d0000164Asv0000103Csd00003106bcsci
alias: pci:v000014E4d0000164Asv0000103Csd00003101bcsci*
depends:
vermagic: 2.6.32-431.el6.x86_64 SMP mod_unload modversions
parm: disable_msi:Disable Message Signaled Interrupt (MSI) (int)
yum update 系统更新
yum -y update
Centos6.5更新e1000网卡驱动Centos6.5更新e1000网卡驱动

reboot
查看系统版本查看网卡驱动
[root@localhost ~]# modinfo bnx2
filename: /lib/modules/2.6.32-642.el6.x86_64/kernel/drivers/net/bnx2.ko
firmware: bnx2/bnx2-rv2p-09ax-6.0.17.fw
firmware: bnx2/bnx2-rv2p-09-6.0.17.fw
firmware: bnx2/bnx2-mips-09-6.2.1b.fw
firmware: bnx2/bnx2-rv2p-06-6.0.15.fw
firmware: bnx2/bnx2-mips-06-6.2.3.fw
version: 2.2.6
license: GPL
description: QLogic BCM5706/5708/5709/5716 Driver
author: Michael Chan <mchan@broadcom.com>
srcversion: 16BA5FA9F22B085C53076EC
alias: pci:v000014E4d0000163Csvsdbcsci
alias: pci:v000014E4d0000163Bsvsdbcsci
alias: pci:v000014E4d0000163Asvsdbcsci
alias: pci:v000014E4d00001639svsdbcsci
alias: pci:v000014E4d000016ACsvsdbcsci
alias: pci:v000014E4d000016AAsvsdbcsci
alias: pci:v000014E4d000016AAsv0000103Csd00003102bcsci
alias: pci:v000014E4d0000164Csvsdbcsci
alias: pci:v000014E4d0000164Asvsdbcsci
alias: pci:v000014E4d0000164Asv0000103Csd00003106bcsci
alias: pci:v000014E4d0000164Asv0000103Csd00003101bcsci*
depends:
vermagic: 2.6.32-642.el6.x86_64 SMP mod_unload modversions
parm: disable_msi:Disable Message Signaled Interrupt (MSI) (int)
系统更新了，网卡也进行了更新，下面就是看系统网卡是否正常