+PDCP Flow Diagram
+~~~~~~~~~~~~~~~~~
+
+Based on 3GPP TS 36.323 Evolved Universal Terrestrial Radio Access (E-UTRA);
+Packet Data Convergence Protocol (PDCP) specification
+
+.. code-block:: c
+
+ Transmitting PDCP Entity Receiving PDCP Entity
+ | ^
+ | +-----------|-----------+
+ V | In order delivery and |
+ +---------|----------+ | Duplicate detection |
+ | Sequence Numbering | | (Data Plane only) |
+ +---------|----------+ +-----------|-----------+
+ | |
+ +---------|----------+ +-----------|----------+
+ | Header Compression*| | Header Decompression*|
+ | (Data-Plane only) | | (Data Plane only) |
+ +---------|----------+ +-----------|----------+
+ | |
+ +---------|-----------+ +-----------|----------+
+ | Integrity Protection| |Integrity Verification|
+ | (Control Plane only)| | (Control Plane only) |
+ +---------|-----------+ +-----------|----------+
+ +---------|-----------+ +----------|----------+
+ | Ciphering | | Deciphering |
+ +---------|-----------+ +----------|----------+
+ +---------|-----------+ +----------|----------+
+ | Add PDCP header | | Remove PDCP Header |
+ +---------|-----------+ +----------|----------+
+ | |
+ +----------------->>----------------+
+
+
+.. note::
+
+ * Header Compression and decompression are not supported currently.
+
+Just like IPsec, in case of PDCP also header addition/deletion, cipher/
+de-cipher, integrity protection/verification is done based on the action
+type chosen.
+
+DOCSIS Protocol
+~~~~~~~~~~~~~~~
+
+The Data Over Cable Service Interface Specification (DOCSIS) support comprises
+the combination of encryption/decryption and CRC generation/verification, for
+use in a DOCSIS-MAC pipeline.
+
+.. code-block:: c
+
+
+ Downlink Uplink
+ -------- ------
+
+ Ethernet frame Ethernet frame
+ from core network to core network
+ | ^
+ ~ |
+ | ~ ----+
+ V | |
+ +---------|----------+ +----------|---------+ |
+ | CRC generation | | CRC verification | |
+ +---------|----------+ +----------|---------+ | combined
+ | | > Crypto + CRC
+ +---------|----------+ +----------|---------+ |
+ | Encryption | | Decryption | |
+ +---------|----------+ +----------|---------+ |
+ | ^ |
+ ~ | ----+
+ | ~
+ V |
+ DOCSIS frame DOCSIS frame
+ to Cable Modem from Cable Modem
+
+The encryption/decryption is a combination of CBC and CFB modes using either AES
+or DES algorithms as specified in the DOCSIS Security Specification (from DPDK
+lib_rtecryptodev perspective, these are RTE_CRYPTO_CIPHER_AES_DOCSISBPI and
+RTE_CRYPTO_CIPHER_DES_DOCSISBPI).
+
+The CRC is Ethernet CRC-32 as specified in Ethernet/[ISO/IEC 8802-3].
+
+.. note::
+
+ * The offset and length of data for which CRC needs to be computed are
+ specified via the auth offset and length fields of the rte_crypto_sym_op.
+ * Other DOCSIS protocol functionality such as Header Checksum (HCS)
+ calculation may be added in the future.
+