United States
Q
What is the default DRAM and flash configuration on Cisco ISR 4000 routers?
A
Cisco ISR 4000 routers ship with model-dependent DRAM from 2 GB to 8 GB and onboard flash from 2 GB to 16 GB by default.
Q
How do I check current memory and flash usage on an ISR 4000?
A
Use IOS XE CLI: “show memory statistics platform” for DRAM and “show flash:” or “dir flash:” for flash usage.
Q
Can I upgrade the DRAM on my ISR 4000 series router?
A
Yes. You can install Cisco-approved DRAM upgrade kits to expand memory up to 16 GB, subject to your specific ISR 4000 model.
Q
What flash module types are supported by ISR 4000 routers?
A
Supported media include onboard embedded flash, mini-USB flash drives, EHWIC flash modules and High-Density MultiMedia (SD) cards.
Q
What is the maximum memory and flash capacity for ISR 4000?
A
Depending on model, you can have up to 16 GB DDR4 DRAM and a combined total of 32 GB flash via onboard and external modules.
Q
How does DRAM and flash capacity impact ISR 4000 performance?
A
More DRAM supports additional IOS XE services (encryption, SD-WAN, IPS), while larger flash speeds up image loading and log caching.
Q
Which IOS XE features on ISR 4000 demand the most memory?
A
High-throughput encryption, SD-WAN, advanced threat defense and containerized services require larger DRAM allocations.
Q
What steps are required to upgrade flash on an ISR 4000?
A
Power off, insert the approved flash module (mini-USB, SD or EHWIC), power on, then verify with “show flash:”.
Q
Does ISR 4000 support external USB flash drives?
A
Yes. The mini-USB port accepts up to 128 GB USB flash drives for additional IOS images or file storage.
Q
What are best practices for optimizing memory usage on ISR 4000?
A
Disable unused features, monitor with “show memory”, configure memory pools, upgrade to latest IOS XE and scale DRAM as needed.
Q
How much flash is recommended for IOS XE image installation?
A
Allocate at least 4 GB flash per image (typical IOS XE release is 1.5–2 GB), plus 2 GB for logs and temporary files.
Q
Are flash modules hot-swappable on the ISR 4000 series?
A
Mini-USB and SD card modules are hot-pluggable; EHWIC flash modules require a shutdown of the corresponding interface slot.
Q
How do I back up my ISR 4000 flash contents?
A
Use CLI commands such as “copy flash: tftp:” or “copy flash: scp:” to transfer files to a remote server.
Q
Can I use an SD card as primary flash storage on ISR 4000?
A
Yes. The high-density MultiMedia card slot supports SD and microSD cards as supplemental flash storage.
Q
How do I safely clear or format flash memory on ISR 4000?
A
Use “delete /recursive flash:” to remove files, then “format flash:” to wipe and rebuild the flash file system.
Q
What diagnostic commands help troubleshoot memory issues on ISR 4000?
A
Key commands include “show platform hardware qfp active memory summary”, “show memory free” and “show processes memory sorted”.
