Packet Data Convergence Protocol (PDCP) for LTE
This protocol sits between the RLC and RRC layers in the LTE air interface (connecting an LTE UE with an eNodeB).
Protocol dependencies
A preference setting may be enabled to allow dissection of (some) RRC payloads. This dissector may be called by the RLC-LTE dissector for signalling PDUs (if preference settings are enabled).
A UDP framing format for PDCP-LTE has been defined (described in packet-pdcp-lte.h, purely for use with Wireshark)
Example traffic
Wireshark
The PDCP-LTE dissector is partly functional. It can decode the PDCP-LTE headers but has limited support for ROHC payloads. There is no support for ciphering. There is support for reading RLC-LTE frames from:
DCT2000 log files, or
using the UDP format defined in packet-pdcp-lte.h. This (BSD-licensed) program gives an example of how you might send PDCP-LTE frames in this format.
Preference Settings
- Show User-Plane uncompessed data as IP. Default is Off.
- Show unciphered Signalling-Plane data as RRC. Default if Off.
- Attempt to decode ROHC data. Default is Off.
- Try Heuristic LTE-PDCP over UDP framing. Default is Off.
- Which layer info to show in Info column. Default is RLC.
Example capture file
XXX - Add a simple example capture file to the SampleCaptures page and link from here (see below). Keep this file short, it's also a good idea to gzip it to make it even smaller, as Wireshark can open gzipped files automatically.
Display Filter
A complete list of PDCP-LTE display filter fields can be found in the display filter reference
Show only the PDCP-LTE based traffic:
pdcp-lte
Capture Filter
You cannot directly filter PDCP-LTE protocols while capturing.
External links
3GPP TS 36.323 Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol (PDCP) specification
RFC 3095 RObust Header Compression (ROHC): Framework and four profiles: RTP, UDP, ESP, and uncompressed
Example program that generates and sends frames using the supported UDP framing format
Discussion
It is recommended that you use current sources or a recent automated build for this and other LTE dissectors.