January 14, 2005
Customers deploying 256 megabytes of memory in a 2600XM will notice that the total amount of memory allocated will not add up to 256 megabytes.
Due to limitations on the way memory is addressed, not all of the 256 megabytes of memory is usable by the router. This is unlike other IOS routers, where the memory will be allocated to the heap and used by IOS features.
The Cisco 2600XM Multiservice Access Routers are now shipping with one 128MB SDRAM DIMM instead of two 64MB SDRAM DIMMs. This allows for the second slot to optionally be populated at the factory with an additional 128MB of SDRAM to achieve 256MB of SDRAM or for the second slot to remain open for future SDRAM memory expansion up to 256MB.
The Cisco 2600XM 256 megabytes support was implemented in order to help customers with large IOS images that could not run within the 128 megabyte limit.
The increase in actual memory availability seen with a 256 MB DRAM upgrade will vary depending upon the size of the IOS image. The uncompressed image size must be a minimum of 16 MB to see any benefit and as the size of the IOS image increases, more benefits can be realized.
To review and read the details of the product bulletins, see
The router uses memory to store the decompressed IOS image and facilitate router operations. Having more DRAM allows the platform to support larger IOS images with more features and has no impact on the platform performance. However, having more memory does allow a platform to store larger data structures, such as routing tables, for example. This benefit of having more memory cannot be realized with the 256 megabyte upgrade.
This is not a defect or a DDTS. The memory is properly reflected in several IOS commands.
To follow the bug ID link below and see detailed bug information, you must be a registered user and you must be logged in.
Cannot use all 256 meg after upgrade of memory on 2600xm.
How To Identify Hardware Levels
To determine if you have a unit with the 128MB DIMM and/or Rommon change, check the following on your unit.
Serial numbers greater than JPE0808120Q, JMX0807L3MM, or JHY0809K0K7
Use the C2600 CLI to view memory type in the router.
Look for the assembly part number on the outside of the router shipping container with the last digits 02, for example, 800-20044-02. If the last 2 digits are 01, these units do not have the change.
Verify that you have ROMMON version is 12.2(8r) or greater.You can tell what version of ROMmon your router has by issuing the show version command from the CLI.
The output is below:
ROM: System Bootstrap, Version 12.2(8r) [cmong 8r], RELEASE SOFTWARE (fc1)
How to Read Memory Outputs on 2600XM 256MB
The following CLI commands and outputs indicate how to understand the output of a 2600XM with 256MB od DRAM.
Always shows memory in chassis based on running image. For example, with 96MB - 64MB & 32MB DIMM, shows 96MB.
Cisco 2651XM (MPC860P) processor (revision 0x02) with 105472K/25600K bytes of memory.
DIMM Slot 0: DIMM Type : Dual-bank DIMM Size : 128MBytes DIMM Slot 1: DIMM Type : Dual-bank DIMM Size : 128MBytes
Amount of processor memory that can be used by system. Based on image and release, and will vary based on image.
Head Total(b) Used(b) Free(b) Lowest(b) Largest(b) Processor 81D19804 78437600 7183876 71253724 71148788 70198836 I/O 6700000 26214400 2808096 23406304 23115584 23124156
Previously, as the image size increased, the amount of usable processor memory would decrease. With the additional memory, new ROMMON and future IOS changes, the processor memory remains constant as image size increases.
For More Information
If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods:
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