Warning: Version 15.2(1) is the first release in the 15.2M train. It has known bugs (CSCue12345 – high CPU with BGP scale). Most admins prefer 15.2(4)M8, but 15.2(1) remains popular for lab use due to its smaller flash footprint (~45MB vs 54MB for later 15.2 releases).
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You cannot flash this image onto any router. The c2800nm prefix specifically targets the following hardware: c2800nm adventerprisek9 mz 152 1 full
| Router Model | DRAM Required | Flash Required | Suitable for this image? | | :--- | :--- | :--- | :--- | | Cisco 2801 | 512 MB | 128 MB | Yes (with upgrades) | | Cisco 2811 | 512 MB (768 MB recommended) | 128 MB | Yes | | Cisco 2821 | 512 MB | 128 MB | Yes | | Cisco 2851 | 512 MB | 128 MB | Yes | Warning: Version 15
Critical Warning: The "full" image size is approximately 54–58 MB. The base flash on many 2800 series routers is only 64 MB. After formatting, you may have insufficient space. Always verify available flash with show flash: before attempting the upgrade. You cannot flash this image onto any router
Furthermore, this IOS version (15.2(1)) requires a minimum of 512 MB of DRAM. If your router has 256 MB, it will crash during boot (boot loop). Upgrade the DRAM first using Cisco-approved memory modules.