Cisco 4000 Manual page 11

Memory Requirements in the Cisco 4000 Series
Each module in the Cisco 4000 series can change memory configurations to accommodate
internetworking demands. The memory requirements are affected by the following factors:
•
The number of Cisco IOS software images a system stores can be increase by adding
Flash memory.
•
Network expansion, the use of additional protocols or Cisco IOS services, or newer
Cisco IOS releases may require additional main memory
•
I/O performance or more physical or virtual interfaces may require additional shared
memory.
Shared Memory Requirements
The standard configuration for shared memory is 4 MB for the Cisco 4000 series. 4 MB of
memory is enough for most configurations with fewer than 24 physical or virtual interfaces.
Routers with multiple ISDN BRI network processor modules or with 24 or more physical
and virtual interfaces require 8 to 16 MB of shared memory.
Note
affect main or flash memory requirements.
The types and numbers of network processor modules installed in a system does not
Overview of the Cisco 4000 Series Routers 1-11
Memory Systems