Loading and Managing System Images Files載入與管理系統映像檔

Note: ROMMON = ROM monitor.

註：ROMMON＝ROM 監控程式（ROM monitor）。

1. The bootstrap code checks the boot field of the configuration register. The configuration register is a 16-bit value; the lower 4 bits are the boot field. The boot field tells the router how to boot up. The boot field can indicate that the router looks for the Cisco IOS image in flash memory, or looks in the startup configuration file (if one exists) for commands that tell the router how to boot, or looks on a remote TFTP server. Alternatively, the boot field can specify that no Cisco IOS image will be loaded, and the router should start a Cisco ROM monitor (ROMMON) session.開機程式碼會檢查設定暫存器的開機欄位（boot field）。設定暫存器是一個 16 位元的數值，其中最低的 4 個位元即為開機欄位。開機欄位會告訴路由器該如何開機。開機欄位可以指示路由器在快閃記憶體中尋找 Cisco IOS 映像檔，或在啟動設定檔（若存在）中尋找告訴路由器如何開機的指令，或在遠端 TFTP 伺服器上尋找。此外，開機欄位也可以指定不載入任何 Cisco IOS 映像檔，讓路由器改為啟動 Cisco ROM 監控程式（ROMMON）工作階段。
2. The bootstrap code evaluates the configuration register boot field value as described in the following list. In a configuration register value, the "0x" indicates that the digits that follow are in hexadecimal notation. A configuration register value of 0x2102, which is also a default factory setting, has a boot field value of 0x2"the far right digit in the register value is 2 and represents the lowest 4 bits of the register.開機程式碼會依照以下清單所述的方式，評估設定暫存器開機欄位的數值。在設定暫存器值中，「0x」表示接下來的數字是十六進位表示法。設定暫存器值 0x2102（同時也是出廠預設值）的開機欄位值為 0x2，也就是暫存器值中最右邊的數字 2，代表暫存器最低的 4 個位元。
   • If the boot field value is 0x0, the router boots to the ROMMON session.若開機欄位值為 0x0，路由器會開機進入 ROMMON 工作階段。
   • If the boot field value is 0x1, the router searches flash memory for Cisco IOS images.若開機欄位值為 0x1，路由器會在快閃記憶體中搜尋 Cisco IOS 映像檔。
   • If the boot field value is 0x2 to 0xF, the bootstrap code parses the startup configuration file in NVRAM for boot system commands that specify the name and location of the Cisco IOS Software image to load. (Examples of boot system commands will follow.) If boot system commands are found, the router sequentially processes each boot system command in the configuration, until a valid image is found. If there are no boot system commands in the configuration, the router searches the flash memory for a Cisco IOS image.若開機欄位值為 0x2 到 0xF，開機程式碼會剖析 NVRAM 中的啟動設定檔，尋找 boot system 指令，該指令指定了要載入的 Cisco IOS 軟體映像檔名稱與位置（後面將提供 boot system 指令的範例）。若找到 boot system 指令，路由器會依序處理設定中的每一個 boot system 指令，直到找到有效的映像檔為止。若設定中沒有任何 boot system 指令，路由器會在快閃記憶體中搜尋 Cisco IOS 映像檔。
3. If the router searches for and finds valid Cisco IOS images in flash memory, it loads the first valid image and runs it.若路由器搜尋後在快閃記憶體中找到有效的 Cisco IOS 映像檔，會載入第一個有效的映像檔並執行。
4. If it does not find a valid Cisco IOS image in flash memory, the router attempts to boot from a network TFTP server using the boot field value as part of the Cisco IOS image filename.若在快閃記憶體中找不到有效的 Cisco IOS 映像檔，路由器會嘗試從網路上的 TFTP 伺服器開機，並使用開機欄位值作為 Cisco IOS 映像檔檔名的一部分。
5. After six unsuccessful attempts at locating a TFTP server, the router starts a ROMMON session.在六次尋找 TFTP 伺服器失敗後，路由器會啟動 ROMMON 工作階段。

Branch(config)#  boot system flash:/c2900-universalk9-mz.SPA.152-4.M1.bin

Branch(config)# boot system tftp://c2900-universalk9-mz.SPA.152-4.M1.bin
Branch(config)# boot system rom

System Bootstrap, Version 15.0(1r)M15, RELEASE SOFTWARE (fc1)
<... output omitted ...>
Total memory size = 512 MB - On-board = 512 MB, DIMM0 = 0 MB
CISCO2901/K9 platform with 524288 Kbytes of main memory
Main memory is configured to 72/-1(On-board/DIMM0) bit mode with ECC enabled
Readonly ROMMON initialized
program load complete, entry point: 0x80803000, size: 0x1b340

IOS Image Load Test 
Digitally Signed Release Software 
program load complete, entry point: 0x81000000, size: 0x5d433c0
Self decompressing the image: ##########################################################################################################################[OK]
<... output omitted ...>

Branch# show version 
Cisco IOS Software, C2900 Software (C2900-UNIVERSALK9-M), Version 15.2(4)M1, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2012 by Cisco Systems, Inc.
Compiled Thu 26-Jul-12 20:54 by prod_rel_team
ROM: System Bootstrap, Version 15.0(1r)M15, RELEASE SOFTWARE (fc1)
Branch uptime is 39 minutes
System returned to ROM by reload at 11:39:24 UTC Tue Nov 20 2012
System image file is "flash0:c2900-universalk9-mz.SPA.152-4.M1.bin"
Last reload type: Normal Reload
Last reload reason: Reload Command
Cisco CISCO2901/K9 (revision 1.0) with 483328K/40960K bytes of memory.
Processor board ID FCZ1642C5XJ
2 Gigabit Ethernet interfaces
1 Serial(sync/async) interface
1 terminal line
DRAM configuration is 64 bits wide with parity enabled.
255K bytes of non-volatile configuration memory.
250880K bytes of ATA System CompactFlash 0 (Read/Write)
<... output omitted ...>
Configuration register is 0x2102

• Cisco IOS versionCisco IOS 版本

  Cisco IOS Software, C2900 Software (C2900-UNIVERSALK9-M), Version 15.2(4)M1, RELEASE SOFTWARE (fc1)

  This line from the example output shows the version of Cisco IOS Software in RAM that the router is using.

  範例輸出中的這一行顯示路由器目前使用、位於 RAM 中的 Cisco IOS 軟體版本。

• ROM bootstrap programROM 開機程式

  ROM: System Bootstrap, Version 15.0(1r)M15, RELEASE SOFTWARE (fc1)

  This line from the example output shows the version of the system bootstrap software that is stored in ROM and was initially used to boot up the router.

  範例輸出中的這一行顯示儲存在 ROM 中、最初用來啟動路由器的系統開機軟體版本。

• Location of Cisco IOS imageCisco IOS 映像檔位置

  System image file is "flash0:c2900-universalk9-mz.SPA.152-4.M1.bin"

  This line from the example output shows where the Cisco IOS image is located and loaded as well as its complete filename.

  範例輸出中的這一行顯示 Cisco IOS 映像檔所在的位置與載入方式，以及其完整檔名。

• Interfaces介面

  2 Gigabit Ethernet interfaces
  1 Serial (sync/async) interface

  This section of the output displays the physical interfaces on the router. In this example, the Cisco 2901 router has two Gigabit Ethernet interfaces and one serial interface.

  輸出中的這一部分顯示路由器上的實體介面。在此範例中，Cisco 2901 路由器有兩個 Gigabit Ethernet 介面與一個序列介面。

• Amount of NVRAMNVRAM 容量

  255 KB of NVRAM

  This line from the example output shows the amount of NVRAM on the router.

  範例輸出中的這一行顯示路由器上的 NVRAM 容量。

• Amount of Flash快閃記憶體容量

  250880 KB of ATA System CompactFlash 0 (Read/Write)

  This line from the example output shows the amount of flash memory on the router.

  範例輸出中的這一行顯示路由器上的快閃記憶體容量。

• Configuration register設定暫存器

  Configuration register is 0x2102

  The last line of the show version command displays the current configured value of the software configuration register in hexadecimal format. This value indicates that the router will attempt to load a Cisco IOS Software image from flash memory and load the startup configuration file from NVRAM. 0x2102 is the factory-setting default.

  show version 指令輸出的最後一行，會以十六進位格式顯示軟體設定暫存器目前設定的數值。此數值表示路由器會嘗試從快閃記憶體載入 Cisco IOS 軟體映像檔，並從 NVRAM 載入啟動設定檔。0x2102 為出廠預設值。

  You can change the value of the configuration register setting from Cisco IOS CLI or as previously mentioned, also from ROMMON session.

  您可以從 Cisco IOS CLI 更改設定暫存器的設定值，如先前所述，也可以從 ROMMON 工作階段更改。

  Here is how you would enter the new value from the Cisco IOS CLI:

  以下說明如何從 Cisco IOS CLI 輸入新的數值：

  Router(config)# config-register 0x2142

  After changing the value, you should exit the global configuration mode and save the configuration changes to NVRAM:

  變更數值後，您應退出全域設定模式，並將設定變更儲存到 NVRAM：

  Router(config)# end
  Router# copy running-config startup-config

  The new configuration register settings are saved to NVRAM but they will take effect only after the next router reload or power cycle.

  新的設定暫存器設定會儲存到 NVRAM，但只有在路由器下次重新載入或重新開機後才會生效。

  You can also verify the configuration register by using the show commands.

  您也可以使用 show 指令來驗證設定暫存器。

  Router#show bootvar 
  BOOT variable = 
  CONFIG_FILE variable does not exist
  BOOTLDR variable does not exist
  Configuration register is 0x2102 (will be 0x2142 at next reload)
  
  Standby not ready to show bootvar