Cisco Cisco IOS Software Release 12.4(23)

This section contains the following sections with information that is specific to the Cisco 3600 series 
routers:

The Cisco 3600 series includes the Cisco 3631, Cisco 3640, Cisco 3640A, and Cisco 3660 routers. As 
modular solutions, the Cisco 3600 series routers enable corporations to increase dialup density and take 
advantage of current and emerging WAN technologies and networking capabilities. The Cisco 3600 
series routers are fully supported by Cisco IOS software, which includes dialup connectivity, 
LAN-to-LAN routing, data and access security, WAN optimization, and multimedia features.

For memory recommendations for the Cisco 3600 series routers in Cisco IOS Release 12.4, see the 

An update to Flash memory to 64MB in Cisco IOS Release 12.4(12) has been made for the following 
images:

c3660-ix-mz 
c3660-bino3s-mz

This increase in Flash memory was due to the increased image size seen between Cisco IOS 
Release 12.4(10) and Release 12.4(12).

Cisco IOS Release 12.4 supports the following Cisco 3600 series routers:

Cisco 3631

Cisco 3640 and Cisco 3640A

Cisco 3660 (Cisco 3661 and Cisco 3662)

For detailed descriptions of the new hardware features, see the 

For additional information about supported hardware for this platform and release, see the 
Cisco Software Advisor at the following location:

 lists the supported interfaces for the Cisco 3600 series routers for Cisco IOS Release 12.4.