It won’t be wrong to say that the Cisco metal box looks like any other server on the outside but the real deal is the memory components inside the Cisco routers. There are many different types of Cisco memories. In this article, you will come to know about main 5 Cisco storage types.

Cisco Storage Solutions

As far as the Cisco router is concerned, it is a specialized computer that runs a custom operating system that has been specifically designed for routing and various other related functions. There are many different types of memories inside a Cisco router and the router does not rely on a hard disk for storage.

Among other types, there are 5 Cisco storage types that are mainly used. Out of these five, there are four main memory types that one needs to be familiar with including Flash, RAM, ROM and NVRAM.

Flash Memory

This memory is included in the Cisco router with the help of SIMM slots. This is used for storing as well as running the custom operating system by Cisco which is also known as the router’s operating system. When you shut down a router, they contents of this flash memory are already saved and not lost.

However, the chip can be flashed and its content can be upgraded similar to flashing the BIOS in a personal computer. When the Cisco router keeps running, the contents of the flash memory are in read-only mode.

As far as the size of flash memory is concerned, the 2500 series router has a range from a minimum of 4 MB to a maximum of 16 MB. You always have the option of adding additional flash memory to the router for meeting the space requirements of the operating system version that you want to run on the router.

For instance, some of the versions of the operating system required at least 8 MB of flash memory whereas there are others that require only a minimum of 4 MB of flash memory. Some of the operating system versions also require 16 MB of flash memory.

When you are planning to upgrade or install flash memory using multiple Single In-Line Memory Modules, it is extremely important to make sure that all are of the same size. For instance, if you’re planning to upgrade a router that already has 8 MB of flash memory, you have the option to add another 8 MB of flash memory or replace the 8 MB unit with 16 MB unit.

It’s not possible to mix and match modules with different storage capabilities. Therefore, you cannot have a module with 8 MB storage and another module with 4 MB storage at the same time. The storage capabilities of both the modules must be equal.

Random Access Memory

As you may already know, it is a very fast memory that is completely lost when the system is powered down or restarted. In a Cisco router, this type of memory is used for running the operating system and system tables. Buffer random access memory is also used for storing routing tables and for various other functions. It is a temporary memory for router configurations. In other words, it can also be said that this type of memory is the volatile or nonpermanent working area of memory on a router.

It is broken up into two main areas by default namely, main processor memory and shared memory. The main processor memory is used for storing ARP tables, running configuration as well as routing table. On the other hand, the shared memory acts as a buffer location for temporary storage of packets. Most of the routers come with 2 MB of random access memory soldered to the system board with one another slot for single in-line memory module for additional random access memory.

As far as the max amount of RAM is concerned, the 2500 series Cisco router can have a maximum of 16 MB of RAM. If the router has a RAM SIMM already installed, the capacity will be used as the main processor memory whereas the on-board RAM will be used as a shared memory. In case no single in-line memory module is present, the 2 MB of on-board RAM will be used for main processor memory as well as shared memory. However, it is recommended to avoid this as it affects the overall performance.

Read Only Memory

In the older Cisco Routers, this type of memory was used for storing the operating system software. However, this type of memory isn’t used for this purpose in the new Cisco routers. As mentioned above, the image of the operating system is stored in flash memory in the newer routers. This type of memory is used for beginning the boot process and it consists of a number of different elements. A micro code which is a set of programming instructions contained in read-only memory is used for implementing these elements.

Non-Volatile Random Access Memory

As the name suggests, this acts as a permanent type of memory. This type of memory is used for storing the start-up configuration file of the Cisco router. Once the operating system image has been loaded by the router, the start-up configurations files settings are applied.

Whenever a change is made to the running configuration of the router, these changes need to be saved in the start-up configurations file or the changes will be lost when the router is powered down. It is important to keep in mind that these changes are stored in random access memory which is always erased when a router is shut down. As far as the size of this memory is concerned, it is a tiny 32 kB in size in the 2500 series router.