Quickly upgrade Cisco routers using drag-and-drop

by George Ou | Mar 13, 2006 6:51:00 PM

Tags: Routers & switches, Network technology, NETWORKING, George Ou, Cisco Router, CF Card, firmware, router, card, Cisco Systems Inc.

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Takeaway: Performing firmware updates and configuration backups for Cisco routers used to take forever. Now, thanks to commodity CF memory and USB memory sticks, these tasks hardly take any time at all.

Note: This article is also available as a download.

Cisco routers have always had a steep learning curve for performing even the most basic administrative tasks, like firmware updates and configuration backups. Now, with commodity CF (compact flash) memory and USB memory sticks, you can handle these tasks quickly and easily.

In the old days, the usual method of upgrading Cisco routers required you to have access to a TFTP or FTP server and you had to have basic network configuration before you could begin to download firmware or configuration files. Even when everything was ready to roll, downloading tens of megabytes of firmware binaries took a couple of minutes or more depending on the speed of the connection to the TFTP server and the size of the firmware. In cases where the TFTP server was located across the Internet or WAN with limited T1-class bandwidth, it could take hours to download a new firmware. FTP servers were a little better because they could deliver the firmware at near wire speeds, but even that took tens of minutes.

Now, with the newer Cisco 1800, 2800, and 3800 series routers, which use commodity CF memory cards that can be loaded into any media adapter, you can do firmware updates in seconds using drag-and-drop. Cisco designed its newest routers to read the FAT file system instead of its primitive proprietary drive format, which couldn't even recover deleted file space unless you ran the time-consuming "squeeze" command. By going with FAT, you can literally stick the CF card in your computer's CF slot (~$9 for a USB 2.0 compact flash adapter, if you don't have one), delete the old firmware, and drag the newest firmware onto the CF card. If your computer has a USB 2.0 adapter, you can expect 20 MB firmware to copy in seconds, whereas it would have taken 10-100 minutes with a TFTP server, depending on connection speed. Even USB 1.1 solutions are preferable to the TFTP or FTP servers.

As a bonus, you can also copy a startup configuration file onto the CF card. Note that while Cisco routers load their firmware from the CF card, router configuration is loaded from NVRAM (nonvolatile RAM), so the router configuration can't be directly booted from the CF card. But you can copy the configuration file from the CF card to NVRAM to recover a configuration file or do it in the reverse direction to back up a configuration.

Once the configuration file is on the CF card and the router boots up with the CF card inserted, you just need to issue this file copy command:

Copy flash:startup-config nvram:startup-config

This assumes you named the configuration file "startup-config" before you dragged it from your computer to the CF card and that the router is in "enable" mode. This command takes the startup configuration on the CF card and transfers it to the nonvolatile RAM of the router, so that it will boot with it the next time your start or restart the router. If you need to back up a good configuration of a router to a CF card, you simply reverse the arguments in the copy command and type:

Copy nvram:startup-config flash:startup-config

This is especially useful if you ever need to replace a defective router and Cisco sends you a new one, which usually comes with the base firmware and no configuration. To convert a factory-fresh router into full production, you simply put the old CF card into the new router and boot it up. Once it has booted with the default configuration and the proper firmware, issue the first copy command listed above and reboot the router. When the router finishes booting, it will be completely operational. This entire process could easily have taken an hour or more if you had to manually copy everything via TFTP or FTP.

In addition to CF card support, the newest Cisco routers with IOS 12.4 or better will even read USB memory sticks. This enables you to upgrade, back up, or recover your firmware and configuration to an additional removable device. Operationally, it's the same as the CF card, only you refer to it as "usbflash:" instead of "flash:".

The one downside to USB adapters is that you can't boot off them. Unlike CF cards, they aren't recognized in Cisco RMON mode. Only a booted router running IOS 12.4 or better can read or write to USB adapters. The plus side to USB adapters is that you can use them as a removable backup medium, whereas the CF card isn't removable since the router can't boot without it.

And finally, this new line of Cisco routers offers significant price benefits. You no longer have to pay hundreds of dollars for Cisco-branded CF or USB flash memory because you can typically find 128 MB CF and USB adapters for $15 or less. Although Cisco might lose a little revenue because you can buy cheaper flash memory, it has made the network engineer's life much easier and gained a lot more customer loyalty.

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