Cisco MEM1841-256U384D
256 to 384MB SODIMM DRAM factory upgrade for the Cisco 1841
Product Highlights
Running advanced Cisco IOS feature sets on your 1841 Integrated Services Router demands adequate DRAM — and running out of memory means degraded performance, failed service deployments, or inability to load the IOS image you need.
The Cisco MEM1841-256U384D is a 128MB SODIMM SDRAM factory upgrade module designed specifically for the Cisco 1841 router. It upgrades routers already equipped with 256MB of total DRAM (128MB fixed onboard plus a 128MB DIMM) to the platform's maximum capacity of 384MB. This additional memory headroom is essential for running feature-rich IOS images that include Advanced IP Services, security (firewall, IPS, VPN), and voice capabilities simultaneously.
The Cisco 1841 is part of the first-generation Integrated Services Router (ISR) family within the Cisco 1800 series. While the platform has reached End-of-Life status, thousands of units remain in production networks, lab environments, and CCNA/CCNP study setups worldwide. Maximizing DRAM to 384MB ensures these routers can load the latest supported IOS releases — up to IOS 15.1(4)M — and handle routing tables, ACLs, and concurrent services without memory pressure.
This is a Cisco-original part number, guaranteeing electrical and mechanical compatibility with the 1841's single DIMM expansion slot. No firmware changes or licensing are required — simply install the module and the router recognizes the additional memory at boot.
Features & Benefits
Maximum Memory Capacity
The MEM1841-256U384D brings the Cisco 1841 to its 384MB maximum DRAM capacity — the highest supported by the platform. This ensures you can run the most feature-rich IOS images available for the 1841 without encountering memory allocation failures or process crashes.
Advanced IOS Feature Support
Memory-intensive IOS feature sets — including Advanced IP Services, Zone-Based Firewall (ZBFW), Intrusion Prevention System (IPS), and IPsec VPN — require significantly more DRAM than the base 128MB configuration. Upgrading to 384MB provides the headroom needed to enable multiple concurrent services on a single router.
Drop-In Compatibility
This 144-pin SODIMM module is engineered to the Cisco 1841's exact memory bus specifications: PC133 SDRAM, Non-ECC, Unbuffered, 3.3V. It installs directly into the router's single DIMM expansion slot with no configuration changes required — the router automatically detects the new memory at startup.
Extend Platform Lifespan
For organizations and lab environments still relying on the Cisco 1841, maximizing DRAM is one of the most cost-effective ways to extend the router's useful life. With 384MB, the platform can comfortably run IOS 15.1(4)M — the latest supported release — ensuring access to the most current bug fixes and features available for this hardware.
Deployment Scenarios
CCNA / CCNP Lab Environment
The Cisco 1841 remains a popular platform for Cisco certification study labs. Upgrading to 384MB DRAM allows lab routers to run IOS 15.1 with Advanced Enterprise Services, giving students access to the full range of routing, switching, and security features needed for hands-on exam preparation.
Small Branch Office Router Maintenance
Organizations maintaining legacy Cisco 1841 routers at small branch sites can extend the platform's service life by maximizing memory. With 384MB DRAM, the router can support concurrent VPN tunnels, firewall policies, and QoS configurations without running into memory exhaustion.
Legacy Network Spare / Replacement Part
For IT teams managing spare parts inventories for end-of-life Cisco 1800 series infrastructure, stocking MEM1841-256U384D modules ensures that replacement or redeployed 1841 routers can be brought to maximum memory capacity quickly and cost-effectively.
General
Memory Specifications
Compatibility
Lifecycle
Compatibility Notes
Compatible Platform
- Cisco 1841 Integrated Services Router (all variants including ADSL over ISDN Bundle, ADSL over POTS Bundle, Security Bundle, and base 1841 ISR)
Prerequisites
- This is a 256MB-to-384MB upgrade part. It assumes the router already has 256MB total DRAM installed (128MB fixed onboard + 128MB in the DIMM slot). The existing 128MB DIMM in the expansion slot must be removed and replaced with the 256MB module from this upgrade to achieve 384MB total.
- The Cisco 1841 has one (1) DIMM expansion slot in addition to 128MB of non-removable onboard DRAM.
Supported IOS
- Cisco IOS up to 15.1(4)M (the latest supported release for the 1841 platform).
EOL Notice
- The Cisco 1841 platform reached End-of-Sale on November 1, 2011 and Last Date of Support on October 31, 2016. Cisco TAC support is no longer available; third-party maintenance providers may offer continued support.
Downloads & Resources
Frequently Asked Questions
| Part Number | Product | Key Difference |
|---|---|---|
| MEM1841-256D | Cisco 256MB DRAM for 1841 | Standalone 256MB DIMM module; use when upgrading from base 128MB onboard-only to 256MB total (not a factory upgrade SKU). |
| MEM1841-128D | Cisco 128MB DRAM for 1841 | 128MB standalone DIMM; brings base 1841 from 128MB to 256MB total — half the capacity of the 256U384D upgrade path. |
| MEM1841-128U256D | Cisco 128 to 256MB DRAM Upgrade for 1841 | Factory upgrade SKU from 128MB to 256MB total; choose MEM1841-256U384D instead if you need the full 384MB maximum. |
| MEM1841-128U384D | Cisco 128 to 384MB DRAM Upgrade for 1841 | Factory upgrade from base 128MB to 384MB total; use this SKU if your 1841 has only the default 128MB onboard with no DIMM installed. |