写的比较乱，但大概过程基本就是这样！
一、之前的升级步骤级失败原因分析：
我是按这个步骤升级的：
升级方法：
1、console控制AC，重启进入boot模式。
2、setconfig设置本机的ip和tftp服务器的ip，然后saveconfi
3、load <bootrom文件>
4、write boot.rom /f
5、load <config.rom文件>
6、write config.rom
7、重启AC，并进boot模式
8、load <img文件>
9、write nos.img /f
10、重启即可。查看版本为7.0版本。
厂家工程师说，应该先升级config.rom，再升级boot.rom。从小文件开始升级比较稳妥。
第一次升级到write DCWS-6028_7.0.3.0(R0011.0025)_nos.img /f这一步的时候，也是提示diss is full，我就用delete nos.img命令删除了原有的img，然后重启。
于是重启后就出现，下图的提示：
然后就是反复的重启了。这个时候dir看到的是如下的内容：
没有nos.img文件了，而报错也是提示找不到primary和backup的nos.img文件。
PS：感觉是因为升级的过程有问题，把文件搞乱了。系统启动找不到nos.img文件，所以总是循环报错。但是nos.img是确确实实升级上去并保存了，是存在的。最后我明白原因了，因为第一次升级完启动后，BOOT版本还是6.0的，不是7.0，所以也有可能是6.0的boot版本认不出7.0的nos.img，所以报错。
下图是7.0版本Boot的启动界面，这个才对。。
然后就是第二次升级的过程了（第二项内容），我重新理了理过程，尝试升级并升级成功的叙述！
二、第二次升级,CRT重新设置了颜色，为了截图更容易区分。
下图是新版本的命令:
但是BOOT下无法使用TFTP，提示找不到网卡，ping命令也不能用，不知道是什么原因。
用TFTP就提示这个错误（见下图）
但是无论如何也得把nos.img写进去啊！没办法，我只好用xmodem协议传了。Xmodem模式下9600的波特率速度只有1KB/S，整个传完得5个小时，太坑爹了！
我把波特率改成了115200，速度提升到了3KB/S，第一次传没反应，重启后又试了几次就可以了传了，重启完就变成9600了，要再改一次才行。
7.0版本的BOOT下又一个baudrate命令，可以查看和修改波特率。
“Baudrate 》回车”是查看波特率，“Baudrate 115200》回车”是设置波特率为115200。
第一次升级报了个错误，NOS.IMG丢了个文件。好在升级完之后，重启进BOOT，又可以用TFTP了，省了不少事。另外，7.0的BOOT命令有很大变化，DIR看不到原有的config.rom和boot.rom这两个文件了。
因为刚升级的nos.img有文件丢失，所以用TFTP重新升了一个上去，但是这次是用的长文件名DCWS-6028_7.0.3.0(R0011.0025)_nos.img升的。
另外，FLASH的大小只有32M，所以写入的时候会提示下图中的DISK IS FUUL的提示。
我的做法是：删除了nos.img，然后再执行
“write DCWS-6028_7.0.3.0(R0011.0025)_nos.img /f”命令，强制写入！
写入后重启，重启的过程如下：
PS:有几处提示找不到xxx.pem文件，我百度了一下，应该是密钥之类的东西吧!
我把报错的地方用红色字体标出来了。
U-Boot 2011.12-svn59078 (Jan 23 2013 - 15:13:34)MPC83XX, Build: jenkins-Ivy7.0_Wireless_6028_boot-8
Reset Status:
CPU: e300c1, MPC8347_TBGA_A, Rev: 3.0 at 528 MHz, CSB: 264 MHz
I2C: ready
DRAM: 512 MiB (DDR2, 64-bit, ECC off, 264 MHz)
Flash: 32 MiB
Using default environment
In: serial
Out: serial
Err: serial
Net: No ethernet found.
Bootrom version: 7.0.20
Creation date: Jan 23 2013 - 15:13:31
Testing RAM...
0x0A000000 RAM OK.
Loading flash:/dcws-6028_7.0.3.0(r0011.0025)_nos.img ...
## Booting kernel from Legacy Image at 04000100 ...
Image Name: Linux-2.6.21.1
Image Type: PowerPC Linux Kernel Image (gzip compressed)
Data Size: 15486961 Bytes = 14.8 MiB
Load Address: 00000000
Entry Point: 00000000
Verifying Checksum ... OK
Uncompressing Kernel Image ... OK
BusyBox v1.19.3 (2012-03-12 20:53:06 CST) built-in shell (ash)
Enter 'help' for a list of built-in commands.
Current time is Thu Mar 29 00:29:04 2000
Switch Series Switch Operating System
Software Version 7.0.3.0(R0011.0025)
Compiled Apr 09 10:42:12 2013
28 Ethernet/IEEE 802.3 interface(s)
Mac Addr 00-03-0f-2b-ed-c4
%Mar 29 00:29:10 2000 OPENSSL: The file flash:/wsdh512.pem don't exist in the system!
%Mar 29 00:29:10 2000 OPENSSL: The system could't read Diffie Hellman parameters, so need to create! //提示系统无法读取Diffie Hellman 参数，这个东西应该是个加密算法！
%Mar 29 00:29:10 2000 OPENSSL: The system is creating Diffie Hellman parameters, and it will take a few minutes! Please wait... //系统要花几分钟重建
Loading factory config ...
%Mar 29 00:29:17 2000 %LINK-5-CHANGED: Interface Vlan1, changed state to UP
%Mar 29 00:29:19 2000 OPENSSL: The system successfully create Diffie Hellman weak parameters.
%Mar 29 00:33:38 2000 OPENSSL: The system successfully create Diffie Hellman strong parameters. //大意是重建成功了！
web server is on
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/1, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/1, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/2, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/2, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/3, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/3, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/4, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/4, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/5, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/5, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/6, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/6, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/7, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/7, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/8, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/8, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/9, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/9, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/10, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/10, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/11, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/11, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/12, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/12, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/13, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/13, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/14, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/14, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/15, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/15, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/16, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/16, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/17, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/17, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/18, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/18, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/19, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/19, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/20, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/20, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/21, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/21, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/22, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/22, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/23, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/23, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/24, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/24, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/25, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/25, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/26, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/26, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/27, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/27, changed state to DOWN
%Mar 29 00:33:38 2000 %LINK-5-CHANGED: Interface Ethernet1/0/28, changed state to UP
%Mar 29 00:33:38 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/28, changed state to DOWN
%Mar 29 00:33:43 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet1/0/18, changed state to UP
%Mar 29 00:33:44 2000 %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1,changed state to UP
Switch>%Mar 29 00:34:10 2000 WIRELESS_SSL: Certification file don't exist, so need to generate.
Can't find file "flash:/wssl2_cert.pem" error!
Can't find file "flash:/wssl2_key.pem" error!
%Mar 29 00:34:10 2000 WIRELESS_SSL: The system is creating certification file...
%Mar 29 00:34:10 2000 WIRELESS_SSL: The system is creating server RSA key pair...
%Mar 29 00:34:12 2000 WIRELESS_SSL: The system is verifying RSA key pair...
%Mar 29 00:34:20 2000 WIRELESS_SSL: The system write the RSA key into file flash:/wssl2_key.pem.
%Mar 29 00:34:28 2000 WIRELESS_SSL: The system write server certificate into file flash:/wssl2_cert.pem. //这里也有几处错误，是我比较担心的，也没有重建之类的提示，所以不太放心！
Switch> //等了半天没反应，我直接回车，结果就进到这里了