United States
Q
What is the default DRAM and flash memory configuration on a Cisco 3900 Series router?
A
Cisco 3900 Series routers ship with 512 MB or 1 GB of DRAM and 128 MB or 256 MB of flash memory, depending on the exact model and IOS feature set.
Q
What is the maximum DRAM supported by the Cisco 3900 Series router?
A
Cisco 3900 routers support up to 4 GB of DRAM when you install compatible DDR2 SODIMM modules in both memory slots.
Q
How can I verify the DRAM and flash memory on my 3900 router?
A
Use the EXEC command show version or show platform hardware capacity to display installed DRAM and flash memory on a Cisco 3900 Series router.
Q
How do I upgrade DRAM on a Cisco 3900 Series router?
A
Power down the router, open the top cover, install matching DDR2 SODIMM modules in both memory slots, then reassemble and power up to activate the new DRAM.
Q
How do I upgrade flash memory on a Cisco 3900 Series router?
A
Power off the router, insert the supported CompactFlash card into the front slot, power on, and verify with show flash: to confirm the new capacity.
Q
What are the recommended memory modules for Cisco 3900 Series routers?
A
Use Cisco-approved DDR2 PC2-4200 SODIMMs for DRAM and Cisco-branded 256 MB, 512 MB or 1 GB CompactFlash cards for flash to ensure compatibility and stability.
Q
Why is DRAM important for 3900 router performance?
A
DRAM handles routing tables, process queues, and feature operations; adequate DRAM prevents slow routing updates and supports advanced IOS features.
Q
Why is flash memory critical for Cisco 3900 routers?
A
Flash stores the IOS image, configuration files, and logs; sufficient flash capacity ensures room for multiple IOS versions and recovery images.
Q
How does insufficient DRAM affect router performance?
A
Low DRAM can cause IOS feature failures, routing protocol flaps, and system reloads due to memory exhaustion under heavy traffic or feature loads.
Q
How do I troubleshoot memory-related errors on a 3900 Series router?
A
Check logs with show logging, monitor memory pools via show platform hardware capacity, and run diagnostic tests using diagnostic start module all.
Q
Can I mix different DRAM module sizes on Cisco 3900 routers?
A
No, both SODIMM slots must contain matched DDR2 modules of the same capacity and speed for proper operation.
Q
How do I clear or reset flash memory on a 3900 router?
A
Use the erase flash: command in privileged EXEC mode, then reload the router to remove all files and reset flash to factory state.
Q
What memory configuration is required for Cisco IOS feature sets on a 3900 router?
A
Advanced security or unified communications feature sets typically require at least 2 GB DRAM and 512 MB flash for optimal performance and future upgrades.
Q
How does flash memory impact firmware upgrades on a 3900 Series router?
A
Ample flash ensures you can store both the running and new IOS images simultaneously, enabling rollback if the upgrade fails.
Q
What best practices should I follow for managing memory on Cisco 3900 routers?
A
Regularly monitor memory usage, maintain IOS images and backups in flash, use approved modules, and schedule upgrades before reaching capacity thresholds.
Q
How do I back up and restore flash contents on a Cisco 3900 Series router?
A
Use the copy flash: tftp: command to back up and copy tftp: flash: to restore, ensuring you specify correct file paths and IP addresses.
