Cisco MEM2851-256D enterprise networking (router/Catalyst switch/UCS families) Telecom System Card / Module

The Cisco MEM2851-256D is a 256MB DRAM module built for the Cisco 2851 Integrated Services Router, the largest model in the first-generation 2800 Series ISR family. It adds to the router’s main system memory, which Cisco IOS uses for routing tables, packet buffering and the security, voice and VPN feature bundles the 2851 was commonly deployed to run; the base memory configuration on these routers frequently needed a module of this kind added before a fuller IOS feature set would run reliably. It uses the DRAM architecture and slot layout specific to the 2800 Series and is not interchangeable with the memory used on the later 2900 Series ISR G2. The 2851 has long been end-of-sale but a number remain in service in legacy branch and lab environments, where a memory upgrade like this extends the router’s useful working life. Tech-Star (UK-based, shipped worldwide) stocks Cisco components to support ongoing network maintenance.