Cisco MEM-CF-256MB
256MB Compact Flash for Cisco 1900, 2900, 3900 ISR, Original Cisco
Product Highlights
When your Cisco ISR G2 router needs a reliable, factory-standard CompactFlash card to store its IOS system image, startup configuration, and operational data files, the Cisco MEM-CF-256MB delivers exactly that — with the assurance of genuine Cisco compatibility.
This 256MB CompactFlash memory card is purpose-built for the Cisco 1900, 2900, and 3900 Series Integrated Services Routers. It serves as the default flash storage in Slot 0, which is required for the router to boot and perform normal file operations. Unlike generic third-party CF cards, this Advanced Capability CompactFlash is validated by Cisco to avoid the "unsupported compact flash detected" warnings that legacy or off-brand cards can trigger — warnings that indicate potential performance degradation.
Whether you're replacing a failed CF card, provisioning a spare for disaster recovery, or standardizing your flash inventory across a fleet of ISR G2 branch routers, the MEM-CF-256MB provides a straightforward, cost-effective solution. It supports online insertion and removal (OIR), so you can swap cards without powering down the router or disrupting other interfaces. For environments that require larger IOS feature sets or additional file storage, Cisco also offers higher-density upgrade paths from 256MB to 512MB, 2GB, or 4GB.
Features & Benefits
Genuine Cisco Advanced Capability CompactFlash
The MEM-CF-256MB is an original Cisco CompactFlash card that supports True IDE mode and Multi-Word DMA mode — the two transfer modes required by ISR G2 platforms. Using genuine Cisco CF eliminates the risk of unsupported-card warnings and the performance degradation that can accompany non-validated flash media.
Essential Boot & Storage Media
Cisco ISR G2 routers rely on the CompactFlash in Slot 0 to store the system image, configuration files, and software data files. The CF card must be present in Slot 0 for the router to boot and perform normal operations. The MEM-CF-256MB is the factory-default density shipped in Slot 0, making it the ideal direct replacement or spare.
Online Insertion and Removal (OIR)
The ISR G2 platform supports hot-swapping CompactFlash cards. OIR allows you to replace the MEM-CF-256MB without powering down the router or affecting the operation of other interfaces — preserving routing tables and active sessions during maintenance windows.
Broad ISR G2 Platform Compatibility
A single part number covers the entire ISR G2 portfolio — Cisco 1900, 2900, and 3900 Series routers. This simplifies procurement and sparing across multi-site deployments where different router models may be in use at different branch offices.
Deployment Scenarios
Factory-Default Slot 0 Replacement
If the original 256MB CompactFlash in your ISR G2 router has failed or become corrupted, the MEM-CF-256MB provides a like-for-like replacement. Restore the router to its factory-default flash configuration and reload the IOS image to get back online quickly.
Disaster Recovery Sparing
Maintain pre-loaded spare CF cards with a known-good IOS image and baseline configuration. In the event of a router failure, swap in the spare MEM-CF-256MB and boot the replacement unit in minutes rather than hours.
Multi-Site ISR G2 Fleet Standardization
Organizations operating dozens or hundreds of Cisco 1900, 2900, and 3900 routers across branch offices benefit from stocking a common CF part number. The MEM-CF-256MB is shared across all ISR G2 models, reducing SKU complexity in your spares inventory.
General
Technical
Compatibility
Compatibility Notes
Compatible Platforms
- Cisco 1900 Series ISR (e.g., CISCO1921, CISCO1941)
- Cisco 2900 Series ISR (e.g., CISCO2901, CISCO2911, CISCO2921, CISCO2951)
- Cisco 3900 Series ISR (e.g., CISCO3925, CISCO3925E, CISCO3945, CISCO3945E)
Important Notes
- Only Advanced Capability CompactFlash cards purchased from Cisco are supported in ISR G2 routers. Legacy CF cards will trigger an unsupported-card warning and may degrade system performance.
- The CF card uses a Class C file system. Format new cards using FAT32 if formatting from a PC.
- ISR G2 routers have two external CF slots. Slot 0 is required for boot; Slot 1 can be used for overflow storage.
Downloads & Resources
Frequently Asked Questions
| Part Number | Product | Key Difference |
|---|---|---|
| MEM-CF-256U512MB | 256MB to 512MB CF Upgrade | Upgrade path from 256MB to 512MB for ISR G2 routers needing additional flash capacity |
| MEM-CF-2GB | 2GB Compact Flash | Higher-density 2GB CF card for larger IOS feature sets and additional file storage on ISR G2 |
| MEM-CF-256U4GB | 256MB to 4GB CF Upgrade | Maximum capacity upgrade from 256MB to 4GB for ISR 1900/2900/3900 routers |
| MEM-CF-4GB | 4GB Compact Flash | 4GB CF card for ISR G2 routers running advanced IOS images or storing multiple image versions |