An Interface Descriptor Block, or simply IDB, is a portion of memory or Cisco

Cisco

Cisco may refer to:Companies:*Cisco Systems, a computer networking company* Certis CISCO, corporatised entity of the former Commercial and Industrial Security Corporation in Singapore...

 IOS

Cisco IOS

Cisco IOS is the software used on the vast majority of Cisco Systems routers and current Cisco network switches...

 internal data structure that contains information such as the IP address

IP address

An Internet Protocol address is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing...

, interface state, and packet statistics for networking data. Cisco's IOS software maintains one IDB for each hardware interface in a particular Cisco switch

Network switch

A network switch or switching hub is a computer networking device that connects network segments.The term commonly refers to a multi-port network bridge that processes and routes data at the data link layer of the OSI model...

 or router and one IDB for each subinterface. The number of IDBs present in a system varies with the Cisco hardware platform type.