MEM-3900-2GB=

MEM-3900-2GB= is a memory module for Cisco ISR G2 routing equipment.

DRAM on a router holds the routing tables and the running configuration. The capacity question is usually about routing scale rather than features: a router carrying a full internet routing table needs substantially more memory than one carrying a handful of static routes, and the table has kept growing. A router that was comfortably specified for a full table some years ago may not be now, and the symptom is not a clean failure but instability under load.

Two practical cautions. Memory for routing equipment is usually not generic: the platform expects a specific part, and generic modules of the right physical type and capacity are often rejected or cause instability that is very hard to attribute. And on older platforms, memory is frequently the component that decides whether an upgrade is possible at all, which makes it worth checking before committing to a software plan rather than after.

What this platform is for. The ISR G2 is a branch-office router from Cisco’s second Integrated Services generation, the workhorse of corporate branch networks for most of a decade. Knowing the family’s intended role is usually more useful than the part number when you are working out whether something fits: a chassis built for one job will do another, but rarely well, and the cost of that mismatch tends to show up as throughput or feature limits rather than as an outright failure.

Three questions worth answering before any router purchase, whatever the model. What the throughput requirement actually is with your feature set enabled, rather than the datasheet figure measured without it. Whether the features you need are licensed as well as present, since on most platforms security and performance are separate entitlements. And how many slots or ports you will need in three years, because adding capacity is cheap and replacing a chassis is not.

Where this sits: the ISR G2 generation has been superseded by the ISR 4000 series. Cisco’s own end-of-life notice for the 3900 series set the last day to order as 9 December 2017 and the last day of support as 31 December 2022, and directs customers to the ISR 4000 series, typically the 4431 or 4451, as the migration. The 1900 and 2900 followed the same path.

These routers are nonetheless still in service in very large numbers, which is why the part numbers still get searched for. If you are keeping one running, a spare is a reasonable purchase and we can source it. What you will not get is a software fix or vendor support, and that is the part worth weighing rather than the price.

Tell us the platform, the software release you are trying to get to and what is currently fitted, and we will confirm whether this is the right module and whether the upgrade is actually achievable on that hardware.

Green Code Technologies is a supplier of Cisco, and we supply Huawei and Juniper networking alongside HPE, Dell, Samsung, Netgear, Ubiquiti and Asus. We would rather tell you a part is no longer supported, or that we need to check it, than take an order for something that will not do what you need.