基礎網路管理 第四章 路由器備份與復原 製作：林錦財

大綱 記憶體、檔案系統與暫存器 路由器啟動程序 忘記密碼之復原程序 備份與復原程序

路由器內部元件 NVRAM RAM 組態暫存器 ROM 埠 Flash Slide 1 of 1 Purpose: Emphasize: Note: RAM - Packet buffers, running configurations, running IOS ROM - POST, Rom Monitor, Baby IOS (Rxboot) NVRAM - Backup configurations, Config register Flash - IOS Flash memory is non-volatile. It behaves like a file system. It is more expensive than NVRAM. It is readable and writeable. The 2500 routers run from flash. If it is running IOS from flash, then the flash is in the readable state. Use the boot system comma??? 埠 Flash

路由器加電/啟動順序 加電自檢 (POST) 載入並運行啟動引導微代碼 尋找IOS映像檔 載入IOS映像檔 尋找組態檔 載入組態檔 正常運行 Slide 1 of 1 Purpose: Emphasize: In a later slide, there is a very detailed flowchart of the router startup process.

ROM 功能 存放完成基本功能的微代碼 ROM POST Bootstrap show version ROM monitor 控制臺 Mini IOS Slide 1 of 1 Purpose: Emphasize: Note: Mini IOS is the Rxboot mode. One use of the Rom Monitor is for password recovery. From Rom Monitor, you can set the config register to 0x2142 so the NVRAM will be ignored during startup. 存放完成基本功能的微代碼

尋找IOS映像檔 搜索順序: 1. 檢查組態暫存器 2. 解析NVRAM中的組態檔 3. 預設使用Flash中的第一個檔 show startup-config NVRAM 組態暫存器 show version 控制臺 Flash 搜索順序: 1. 檢查組態暫存器 2. 解析NVRAM中的組態檔 3. 預設使用Flash中的第一個檔 4. 嘗試從網路啟動 5. RXBOOT 6. ROMMON IOS Slide 1 of 1 Purpose: Emphasize: Note: There is a detail flowchart of the router startup process on the next slide.

路由器啟動流程圖 START Slide 1 of 1 Purpose: Boot field =1 0x1 檢查 start-up config Boot system 命令 ? START No Yes 做所述 之開機 Yes No 有效的 IOS在 Flash 中? No Yes 從Flash 使用 IOS Boot field =0 0x0 No No 嘗試 從網路 取得 IOS Yes Yes 5 次 失敗? 執行 ROM Monitor No Slide 1 of 1 Purpose: Emphasize: Go through the flow from the START state to the Normal Startup Complete state. Note: This is a one layer slide. Boot field = last four bits of the config register. Config register is discussed in a later slide. Refer to the Doc CD ROM or the IMCR class for more details on the config register. Yes Config reg bit 13=1 ? Yes 成功 ? 從網路 使用檔案 用ROM中 IOS (RXBoot 模式) No 完成 正常的 啟動 有效的 config ? Config reg bit 6=1 ? No Yes 載入 IOS Yes No SETUP DIALOG

檢查組態暫存器 START Slide 1 of 1 Purpose: Boot field =1 0x1 檢查 start-up config Boot system 命令 ? START No Yes 做所述 之開機 Yes No 有效的 IOS在 Flash 中? No Yes 從Flash 使用 IOS Boot field =0 0x0 No No 嘗試 從網路 取得 IOS Yes Yes 5 次 失敗? 執行 ROM Monitor No Slide 1 of 1 Purpose: Emphasize: Go through the flow from the START state to the Normal Startup Complete state. Note: This is a one layer slide. Boot field = last four bits of the config register. Config register is discussed in a later slide. Refer to the Doc CD ROM or the IMCR class for more details on the config register. Yes Config reg bit 13=1 ? Yes 成功 ? 從網路 使用檔案 用ROM中 IOS (RXBoot 模式) No 完成 正常的 啟動 有效的 config ? Config reg bit 6=1 ? No Yes 載入 IOS Yes No SETUP DIALOG

用命令show version所顯示的組態暫存器值 確認目前的組態暫存器值 wg_ro_a#show version Cisco Internetwork Operating System Software IOS (tm) 2500 Software (C2500-JS-L), Version 12.0(3), RELEASE SOFTWARE (fc1) Copyright (c) 1986-1999 by cisco Systems, Inc. Compiled Mon 08-Feb-99 18:18 by phanguye Image text-base: 0x03050C84, data-base: 0x00001000 ROM: System Bootstrap, Version 11.0(10c), SOFTWARE BOOTFLASH: 3000 Bootstrap Software (IGS-BOOT-R), Version 11.0(10c), RELEASE SOFTWARE (fc1) wg_ro_a uptime is 20 minutes System restarted by reload System image file is "flash:c2500-js-l_120-3.bin" --More-- Configuration register is 0x2102 Slide 1 of 1 Purpose: Emphasize: Use the show version command to display the value of the Config register setting. When you change the config register, we will see from the show version output: Configuration register is 0x2102 (will be 0x2142 at next reload). The new config register value will be used at the next reload. 用命令show version所顯示的組態暫存器值

設定組態暫存器的值 組態暫存器的3, 2, 1和0位元是啟動選項位元 Router#configure terminal Router(config)#config-register 0x2102 [Ctrl-Z] Router#reload 組態暫存器的3, 2, 1和0位元是啟動選項位元 Slide 1 of 4 Purpose: This slide shows how to use the config-register command to set the boot field. Emphasize: Layer 1—Shows the example of the config-register?command. It assumes the network administrator will set the register to the default setting of 0x2102. (0x me???In this course, limit the focus to the boot field that is formed by bits 3, 2, 1 and 0.

設定組態暫存器的值 組態暫存器的3, 2, 1和0位元是啟動選項位元 組態暫存器啟動選項部分的值 涵義 0x0 Router#configure terminal Router(config)#config-register 0x2102 [Ctrl-Z] Router#reload 組態暫存器的3, 2, 1和0位元是啟動選項位元 組態暫存器啟動選項部分的值 涵義 進入ROM monitor模式 (人工啟動時用 b 命令) 0x0 Slide 2 of 4 Purpose: Emphasize: Layer 2—Adds the table that identifies the boot field Configuration Register values and meanings. The first value, 0x0, enters ROM monitor mode. Your students should not enter this mode except for password recovery. Refer students to the Doc CD ???

設定組態暫存器的值 組態暫存器的3, 2, 1和0位元是啟動選項位元 組態暫存器啟動選項部分的值 涵義 0x0 0x1 Router#configure terminal Router(config)#config-register 0x2102 [Ctrl-Z] Router#reload 組態暫存器的3, 2, 1和0位元是啟動選項位元 組態暫存器啟動選項部分的值 涵義 進入ROM monitor模式 (人工啟動時用 b 命令) 0x0 Slide 3 of 4 Purpose: Emphasize: Layer 3—Adds the second boot field value 0x1. This setting automatically boots the system from ROM and provides a subset of the Cisco IOS image (Rxboot mode). Routing is not enabled in the Rxboot mode. However, the router has IP functionality in??鷚Some routers can store a full IOS image in ROM. 自動從ROM啟動 (提供完整IOS的一個子集) 0x1

設定組態暫存器的值 用命令show version來檢查組態暫存器的值 組態暫存器的3, 2, 1和0位元是啟動選項位元 Router#configure terminal Router(config)#config-register 0x2102 [Ctrl-Z] Router#reload 組態暫存器的3, 2, 1和0位元是啟動選項位元 用命令show version來檢查組態暫存器的值 組態暫存器啟動選項部分的值 涵義 進入ROM monitor模式 (人工啟動時用 b 命令) 0x0 Slide 4 of 4 Purpose: Emphasize: Layer 4—Finishes with the third case, a boot field setting in the range of 0x2 to 0xF. The entry of a Configuration Register value in the 0x2 to 0xF range is significant. When the router attempts to boot from the net (Netboot), the bootstrap pro???Notice that the bottom lines of the show version output indicates what the value the config register will be on the next reload. 自動從ROM啟動 (提供完整IOS的一個子集) 0x1 檢查NVRAM之 boot system 命令(如果路由器配有Flash則缺省值為 0x2) 0x2 to 0xF

路由器啟動流程圖 START Slide 1 of 1 Purpose: Boot field =1 0x1 檢查 start-up config Boot system 命令 ? START No Yes 做所述 之開機 Yes No 有效的 IOS在 Flash 中? No Yes 從Flash 使用 IOS Boot field =0 0x0 No No 嘗試 從網路 取得 IOS Yes Yes 5 次 失敗? 執行 ROM Monitor No Slide 1 of 1 Purpose: Emphasize: Go through the flow from the START state to the Normal Startup Complete state. Note: This is a one layer slide. Boot field = last four bits of the config register. Config register is discussed in a later slide. Refer to the Doc CD ROM or the IMCR class for more details on the config register. Yes Config reg bit 13=1 ? Yes 成功 ? 從網路 使用檔案 用ROM中 IOS (RXBoot 模式) No 完成 正常的 啟動 有效的 config ? Config reg bit 6=1 ? No Yes 載入 IOS Yes No SETUP DIALOG

使用boot system命令 以下範例展示多個 boot system 命令之使用方 法，以指定開機的 Cisco IOS 軟體之應變順 序。 預設順序如下： Flash 記憶體 – 從flash載入系統映像。 網路伺服器 – 當 flash 記憶內容毀損時，自 TFTP 伺服器載入系統映像。 ROM – 若 flash 內容毀損且無法從網路伺服器載 入映像，則由 ROM 開機是軟體之最後開機方 式。

boot system flash 從Flash載入IOS映像檔

boot system tftp 從TFTP伺服器載入IOS映像檔

boot system rom 從ROM開機

路由器啟動流程圖 START Slide 1 of 1 Purpose: Boot field =1 0x1 檢查 start-up config Boot system 命令 ? START No Yes 做所述 之開機 Yes No 有效的 IOS在 Flash 中? No Yes 從Flash 使用 IOS Boot field =0 0x0 No No 嘗試 從網路 取得 IOS Yes Yes 5 次 失敗? 執行 ROM Monitor No Slide 1 of 1 Purpose: Emphasize: Go through the flow from the START state to the Normal Startup Complete state. Note: This is a one layer slide. Boot field = last four bits of the config register. Config register is discussed in a later slide. Refer to the Doc CD ROM or the IMCR class for more details on the config register. Yes Config reg bit 13=1 ? Yes 成功 ? 從網路 使用檔案 用ROM中 IOS (RXBoot 模式) No 完成 正常的 啟動 有效的 config ? Config reg bit 6=1 ? No Yes 載入 IOS Yes No SETUP DIALOG

從Flash載入IOS映像檔 Flash中的映像檔解壓縮到RAM中 RAM IOS Flash 控制臺 IOS show flash Slide 1 of 1 Purpose: Emphasize: Note: The 2500 series routers do not operate this way. The 2500 series routers normally run IOS from flash. The IOS in flash is not compressed but it is relocatable. Relocatable means the IOS image can be ran from flash or from RAM. The 2500 can run from RAM if you use the “boot system tftp” command to boot the IOS image. The Rxboot mode is also ran from RAM on the 2500 routers. IOS show flash Flash中的映像檔解壓縮到RAM中

使用 show flash 命令 wg_ro_a# sh flash System flash directory: File Length Name/status 1 10084696 c2500-js-l_120-3.bin [10084760 bytes used, 6692456 available, 16777216 total] 16384K bytes of processor board System flash (Read ONLY) Slide 1 of 1 Purpose: Emphasize: Note: The current state of the flash memory is in Read ONLY mode. It is running IOS from flash. This router has a total of 16MB of flash memory. The flash contains one IOS image and there are 6.69MB available space left in flash.

Flash 毀損情形 若路由器有 flash 映像檔毀損情形，在開機時 會顯示錯誤訊息，此錯誤訊息可能為如下形式 之一： open: read error...requested 0x4 bytes, got 0x0 trouble reading device magic number boot: cannot open "flash:" boot: cannot determine first file name on device "flash:"u 若 flash 映像毀損，則須重新上載 IOS 到路由 器。

載入組態檔 從NVRAM中載入並運行組態檔 如果NVRAM中沒有組態檔, 進入setup模式 RAM NVRAM Config Config IOS show running-config show startup-config 控制臺 Slide 1 of 1 Purpose: Emphasize: Using the default config register value (0x2102), the router will load the config from NVRAM at startup. Setup utility 從NVRAM中載入並運行組態檔 如果NVRAM中沒有組態檔, 進入setup模式

使用 show running 和 show startup 命令 存在RAM中 存在NVRAM中 wg_ro_c#show running-config Building configuration... Current configuration: ! version 12.0 ! -- More -- wg_ro_c#show startup-config Using 1359 out of 32762 bytes ! version 12.0 -- More -- Slide 1 of 1 Purpose: This slide is a repeated slide from chapter 4. Emphasize: 顯示當前運行的和保存的配置情況

copy startup running (合併) 從何處配置參數 RAM NVRAM copy running startup Config Config copy startup running (合併) Slide 1 of 4 Purpose: Emphasize: When copying to RAM, it is always a merge not an overwrite. Explain on the board the difference between a merge versus an overwrite. Explain the general syntax of the copy command: copy <from> <to> With 12.0, the copy command supports a new syntax. The new syntax is explained in a later slide. NVRAM

copy startup running (合併) 從何處配置參數 RAM NVRAM copy running startup Config Config copy startup running (合併) config term (合併) Slide 2 of 4 Purpose: Emphasize: NVRAM Terminal

copy startup running (合併) 從何處配置參數 RAM NVRAM copy running startup Config Config copy startup running (合併) config term (合併) copy tftp run (合併) Console copy tftp start Slide 3 of 4 Purpose: Emphasize: Note: The Cisco TFTP server software which runs on Windows 95/98/NT can be downloaded from the url listed below: http://www.cisco.com/cgi-bin/tablebuild.pl/tftp A Cisco router can also be configured to be a tftp server using the “tftp-server” global configuration command. copy run tftp NVRAM Terminal TFTP 伺服器 copy start tftp TFTP 伺服器

copy startup running (合併) 從何處配置參數 RAM NVRAM copy running startup Config Config copy startup running (合併) config term (合併) erase start copy tftp run (合併) Console Slide 4 of 4 Purpose: Emphasize: copy tftp start Blank 000000 NVRAM Terminal TFTP server 刪除啟動組態檔 copy run tftp copy start tftp TFTP 伺服器

使用copy run tftp 和 copy tftp run 命令 wg_ro_a#copy running-config tftp Address or name of remote host []? 10.1.1.1 Destination filename [running-config]? wgroa.cfg .!! 1684 bytes copied in 13.300 secs (129 bytes/sec) wg_ro_a#copy tftp running-config Source filename []? wgroa.cfg Destination filename [running-config]? Accessing tftp://10.1.1.1/wgroa.cfg... Loading wgroa.cfg from 10.1.1.1 (via Ethernet0): ! [OK - 1684/3072 bytes] 1684 bytes copied in 17.692 secs (99 bytes/sec) Slide 1 of 1 Purpose: Emphasize: Note: Release 12.0 supports new syntax for the “copy” command.

Cisco檔案系統與設備 RAM NVRAM system: nvram: Flash TFTP 伺服器 tftp: flash: Slide 1 of 1 Purpose: Emphasize: In release 12.0, there are new copy commands. These new commands treat the RAM, Flash, NVRAM, tftp, ftp, etc… as a file system. Since at the time when this class was developed, the most common IOS in the field is pre 12.0, these 12.0 commands ar??? Flash TFTP 伺服器 tftp: flash:

Cisco IOS 檔案系統 (IFS) 從第 12 版的 IOS起，提供一個對路由器所有 檔案系統的統一介面，稱之為 Cisco IOS 檔案 系統 (IFS). IFS 提供單一方法管理所有路由器使用之所有 檔案系統，包括： flash 記憶體檔案系統 網路檔案系統 (TFTP, rcp, 與FTP), 以及 讀或寫資料 (如 NVRAM、運行組態、ROM). IFS 使用一共通的前置碼集合以指定檔案系統 設備。

前置碼

IFS 指定格式 IFS 使用 URL 規則指定在網路及網路設備上 的檔案。 IFS 也支援 FTP 檔案傳輸。

IOS 12.0版之前的命令 IOS 12.x 版之命令 configure network (IOS 10.3版以 前) copy rcp running-config copy tftp running-config copy ftp: system:running-config copy rcp: system:running-config copy tftp: system:running-config configure overwrite-network (IOS 10.3版以前) copy rcp startup-config copy tftp startup-config copy ftp: nvram:startup-config copy rcp: nvram:startup-config copy tftp: nvram:startup-config show configuration (IOS 10.3版 以前) show startup-config more nvram:startup-config

IOS 12.0版之前的命令(IOS 10.3 版以前) IOS 12.x 版之命令 write erase (IOS 10.3版以前) erase startup-config erase nvram: write memory (IOS 10.3版以前) copy running-config startup- config copy system:running-config nvram:startup-config write network (IOS 10.3版以前) copy running-config rcp copy running-config tftp copy system:running-config ftp: copy system:running-config rcp: copy system:running-config tftp: write terminal (IOS 10.3版以前) show running-config more system:running-config

IOS的命名規則 要識別不同的版本，IOS檔案有一個命名的規 則 ，其名稱中含有不同之欄位，包括 硬體平台(hardware platform)識別碼 特徵集(feature set)識別碼 版本數字

檔名的四個部份

檔名的第一部份 – 硬體平台 Cisco IOS 檔名的第一部份是識別此映像檔所 適用之硬體平台。

檔名的第二部份 – 特徵集 分類範例 基本(Basic) – 對於硬體平台的基本特徵集，如 IP 及 IP/FW 額外(Plus) – 基本特徵集加上額外的特徵，如 IP Plus, IP/FW Plus, 以及 Enterprise Plus 加密(Encryption) – 一個 56-bit 資料加密特徵集，如 Plus 56, 其於基本或額外特徵集複合，例如 IP/ATM PLUS IPSEC 56 或 Enterprise Plus 56. 對於 Cisco IOS Release 12.2 或之後版本編碼法則為 k8 與 k9: k8 – 在 IOS 12.2 版以後，為小或等於 64-bit 加密。 k9 – 在 IOS 12.2 版以後，為大於 64-bit 加密。

檔名之第三部份格式 檔名的第三部份明示檔案之格式 例如IOS是否以壓縮型式儲存於flash中，以及 可否重調記憶體放置位置 (relocatable)。 若為 flash映像是壓縮的(compressed)，則 IOS 在開機要複製到 RAM 中時，必須解開。 可重調位置的映像則可由flash 複製到 RAM 中執行；至於，不可重調位置的映像，則只能 直接在 flash 中執行。

檔名的第四部份 檔名的第四部份識別 IOS 的版本。對於更新 的 IOS 版本，則增加其版本數字。

管理IOS映像檔 網路 伺服器 路由器 網路 伺服器 c2500-js-l_120-3.bin FLASH Slide 1 of 1 Purpose: Emphasize: This section introduces topics on managing your configuration file and IOS image. FLASH 網路 伺服器

映像檔備份的準備 確認可以存取到網路服務 網路 伺服器 路由器 Slide 1 of 4 Purpose: This slide establishes an overview and reason to use the TFTP server as a load source or backup destination for Cisco IOS software. It then presents the preparation details needed before executing TFTP copies. Emphasize: Geographically distributed routers need a source or backup location for software images. Using a network server allows image and configuration uploads and downloads over the network. The network server can be another router, a workstation, or a ??碭A router can be configured as a tftp server using the tftp-server global configuration command. Layer one - First, you need to check that you have access to the network server. Example, use the ping command to see if you can reach the server.

映像檔備份的準備 確認可以存取到網路服務 確認伺服器上有足夠的空間 網路 伺服器 路由器 Slide 2 of 4 Purpose: Emphasize: Layer 2 — you need to check that you have enough disk space on the tftp server to house the new system image. On the router, use the show flash command to determine the length of the IOS image.

映像檔備份的準備 確認可以訪問到網路服務 確認伺服器上有足夠的空間 確認檔案名 網路 伺服器 路由器 c2500-js-l_120-3.bin 網路 伺服器 路由器 確認可以訪問到網路服務 確認伺服器上有足夠的空間 確認檔案名 Slide 2 of 4 Purpose: Emphasize: Layer 3 — you need to check the naming conventions required on the server. Example, what is the max number of characters allowed in the filename by the server’s O.S? What is the max number of characters allowed in the filename extension by the s??碭

映像檔備份的準備 確認可以訪問到網路服務 確認伺服器上有足夠的空間 確認檔案名 需要時在伺服器上創建檔 網路 伺服器 路由器 c2500-js-l_120-3.bin 網路 伺服器 路由器 確認可以訪問到網路服務 確認伺服器上有足夠的空間 確認檔案名 需要時在伺服器上創建檔 Slide 4 of 4 Purpose: Emphasize: Layer 4—On some Unix server, you may have to first create the file first before you can download the IOS image from the router to the tftp server. You can use the “touch” Unix command to create an empty file on the Unix server.

確認存貯空間並解析檔案名 確認Flash中有足夠空間來存放IOS映像檔 wg_ro_a#show flash System flash directory: File Length Name/status 1 10084696 c2500-js-l_120-3.bin [10084760 bytes used, 6692456 available, 16777216 total] 16384K bytes of processor board System flash (Read ONLY) 確認Flash中有足夠空間來存放IOS映像檔 Slide 1 of 1 Purpose: Emphasize: The show flash command is an important tool to use to gather information about your router memory and image file. Caution students that they must know that they are loading the correct and appropriate image. The name for the Cisco IOS image file??筨The first part of the image name contains the platform on which the image runs. In this example, the platform is C2500. The second part of the name identifies the special capabilities of the image file. A letter or series of letters identifies the feature sets supported in that image. In this example, the j indicates this is an enterprise image, and the s indicates it conta???The third part of the name specifies where the image runs and if the file is compressed. In this example, l indicates the file is relocatable and not compressed. Relocatable means the IOS can be ran from flash or from RAM. You should be careful in reading the Cisco IOS image filename. Some fonts display the lowercase letter “l” and the number 1 as the same character. How you type the characters will impact the ability of the router to load the files correctly. The fourth part of the name indicates the version number. In this example, the version number is 12.0 (3). The final part of the name is the file extension. The .bin extension indicates this file is a binary executable file. The Cisco IOS software naming conventions, name part field meaning, image content, and other details are subject to change. Refer to Cisco Connection Online (CCO) for updated details.

進行映像檔的備份 在升級IOS前備份當前的映像檔 網路 伺服器 copy flash tftp FLASH wg_ro_a#copy flash tftp Source filename []? c2500-js-l_120-3.bin Address or name of remote host []? 10.1.1.1 Destination filename [c2500-js-l_120-3.bin]? !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! <output omitted> 10084696 bytes copied in 709.228 secs (14223 bytes/sec) wg_ro_a# Slide 1 of 1 Purpose: This slide discusses how to create a backup version of a Cisco IOS software image to a tftp server. Emphasize: Routers by default comes with Flash memory that have a preloaded copy of the Cisco IOS software. Although Flash is extremely reliable—good for 65 years and 100,000 rewrites—it is a good idea to make a backup copy of the Cisco IOS software if you??漸The copy command screen output varies depending on the Cisco IOS software level. Determine the platform type of your tftp server prior to beginning the backup procedure. The tftp server may be running Windows, UNIX, Mac or other O.S . Filename and directory access procedures may vary depending on the tftp server platform and platform v??笸 在升級IOS前備份當前的映像檔

從網路升級IOS 載入新的映像檔前對Flash作適當的檔刪除 注意關於映像檔已經存在的提示資訊 網路 伺服器 FLASH wg_ro_a#copy tftp flash Address or name of remote host [10.1.1.1]? Source filename []? c2500-js-l_120-3.bin Destination filename [c2500-js-l_120-3.bin]? Accessing tftp://10.1.1.1/c2500-js-l_120-3.bin... Erase flash: before copying? [confirm] Erasing the flash filesystem will remove all files! Continue? [confirm] Erasing device... eeeee (output omitted) ...erased Erase of flash: complete Loading c2500-js-l_120-3.bin from 10.1.1.1 (via Ethernet0): !!!!!!!!!!!!!!!!!!!! (output omitted) [OK - 10084696/20168704 bytes] Verifying checksum... OK (0x9AA0) 10084696 bytes copied in 309.108 secs (32636 bytes/sec) wg_ro_a# Slide 1 of 1 Purpose: This slide describes how to load a backup version of a Cisco IOS software image from a tftp server to the router. Emphasize: If you need more flash space to load a copy of the Cisco IOS software, then you must first erase the Flash memory. You cannot erase a single image—you must erase all copies of Cisco IOS software from Flash. However, if Flash memory on the router??筨After the tftp transfer is completed, use the show flash command to view the file size to compare its size with that of the original on the server. If the IOS is running from flash, then the flash is in the read only state. To change the flash to a writeable state: you can use the boot system tftp command to boot an IOS from a tftp server and the IOS will be ran from RAM or you can go to the Rxboot mo??館 載入新的映像檔前對Flash作適當的檔刪除 注意關於映像檔已經存在的提示資訊