以3650为例:(适用于大部分接入层网络设备,TFTP最好使用tftp32,可以支持大文件)
1、查看3650IOS信息
WH-KJY-HJ-B16-3650-01#sh flash
Directory of flash:/
    2  -rwx        1036   Feb 7 2012 13:39:20 +08:00  vlan.dat
    3  -rwx           5  Oct 25 2012 16:11:52 +08:00  private-config.text
    5  -rwx        7691  Oct 25 2012 16:11:52 +08:00  config.text
    6  drwx         192   Mar 1 1993 08:07:03 +08:00  c3650-ipservices-mz.122-35.SE5
15998976 bytes total (5480960 bytes free)
2、由于flash空间不够无法导入新版本的IOS,所以只能删除旧的IOS版本
WH-KJY-HJ-B16-3650-01#cd flash:/c3650-ipservices-mz.122-35.SE5 //进入旧的目录下删除
WH-KJY-HJ-B16-3650-01#dir
Directory of flash:/c3650-ipservices-mz.122-35.SE5/
 7  -rwx     8054867   Mar 1 1993 08:05:34 +08:00  c3650-ipservices-mz.122-35.SE5.bin
 8  drwx        4224   Mar 1 1993 08:05:57 +08:00  html
 509  -rwx         616   Mar 1 1993 08:07:03 +08:00  info
15998976 bytes total (5480960 bytes free)
#delete flash:/c3650-ipservices-mz.122-35.SE5/c3650-ipservices-mz.122-35.SE5.bin //删除旧IOS版本(注意在操作这步前,将之前的IOS备份一份保存,以便出现问题可以回退)
Delete filename [/c3650-ipservices-mz.122-35.SE5/c3650-ipservices-mz.122-35.SE5.bin]? 
Delete flash:/c3650-ipservices-mz.122-35.SE5/c3650-ipservices-mz.122-35.SE5.bin? [confirm]
删除完成后查看flash信息:
WH-KJY-HJ-B16-3650-01#sh flash
Directory of flash:/c3650-ipservices-mz.122-35.SE5/
  8  drwx        4224   Mar 1 1993 08:05:57 +08:00  html
  509  -rwx         616   Mar 1 1993 08:07:03 +08:00  info
15998976 bytes total (13536256 bytes free)
3、导入新的IOS
#copy tftp: c3650-ipservicesk9-mz.122-40.SE.bin flash: c3650-ipservicesk9-mz.122-40.SE.bin
4、查看新的IOS导入后flash信息
WH-KJY-HJ-B16-3650-01#sh flash
Directory of flash:/
 2  -rwx        1036   Feb 7 2012 13:39:20 +08:00  vlan.dat
 3  -rwx           5  Oct 25 2012 16:11:52 +08:00  private-config.text
 4  -rwx     9975530   Mar 5 2013 17:59:01 +08:00  c3650-ipservicesk9-mz.122-40.SE.bin
  5  -rwx        7691  Oct 25 2012 16:11:52 +08:00  config.text
  6  drwx         128   Mar 5 2013 17:53:23 +08:00  c3650-ipservices-mz.122-35.SE5  //不带bin后缀这种事目录)
15998976 bytes total (3560448 bytes free)
WH-KJY-HJ-B16-3650-01#sh boot
BOOT path-list      : flash:c3650-ipservices-mz.122-35.SE5/c3650-ipservices-mz.122-35.SE5.bin
Config file         : flash:/config.text
Private Config file : flash:/private-config.text
Enable Break        : no
Manual Boot         : no
HELPER path-list    : 
Auto upgrade        : yes
Auto upgrade path   :
5、更改设备IOS启动顺序,并保存
WH-KJY-HJ-B16-3650-0(config)#boot sys flash:/c3650-ipservicesk9-mz.122-40.SE.bin
WH-KJY-HJ-B16-3650-0(config)#end
WH-KJY-HJ-B16-3650-01#wr
Building configuration...
[OK]
6、查看设备IOS启动项是否是新升级的ios名称
WH-KJY-HJ-B16-3650-01#sh boot
BOOT path-list      : flash:/c3650-ipservicesk9-mz.122-40.SE.bin
Config file         : flash:/config.text
Private Config file : flash:/private-config.text
Enable Break        : no
Manual Boot         : no
HELPER path-list    : 
Auto upgrade        : yes
Auto upgrade path   : 
7、启动项正常后,重启网络设备
WH-KJY-HJ-B16-3650-01#reload
                                    
                                    
                                        
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