NFD

# knowledge about ccnd

ccnd is the original reference implementation of CCN/NDN architecture, and the only NDN forwarder that has been used with real applications.

## ccnd tables

**FIB** is organized as a tree that is stored in a hashtable, and also contains runtime measurement information.

**PIT** is stored in a hashtable, where each PIT entry is linked to a FIB entry.

See [ccnd FIB and PIT data structure](https://www.dropbox.com/s/ms7hp1zgpfgvyru/ccnd-FIB-PIT_20140118.docx) for details.

**ContentStore** is stored in a hashtable, and a skip list maintains a total order over all stored ContentObjects.

See [ccnd ContentStore data structure](https://www.dropbox.com/s/0lw5pqno4wjesiv/ccnd-CS_20130703.docx) for details.

## ccnd forwarding

ccnd has a default forwarding strategy, but it's not easily replaceable.

See [[CcndStrategy|ccnd default strategy]].

ccnd maintains a [[CcndNonce|global Nonce table]] for loop detection.