WAN interfaces are used to provide a point of interconnection between Cisco routers and other network devices. Types of WAN interfaces include
- Basic Rate Interface (BRI)
- Synchronous Serial
- Asynchronous Serial
- High-Speed Serial Interface (HSSI)
- T1 Controller Card
BRI is an Integrated Services Digital Network (ISDN) line that consists of two 64Kbps bearer (B) channels and one 16Kbps data (D) channel.
DCE equipment might consist of a
- Channel Service Unit/Data Service Unit (CSU/DSU)
- BRI NT-1
DTE equipment might consist of a
Four memory components are used by Cisco devices. Those components include ROM, flash, RAM, and NVRAM.
RAM contains the running IOS, with the exception of run from flash (RFF) routers. RAM also contains the running configuration or the active configuration that is used after a machine is booted.