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PDCP layer PDU RFC 2507 ARQ Mechanism


Hi ,

Iam developing a custom dissector on top of UDP which uses PDCP layer PDU RFC 2507 Selective Repeat ARQ Mechanism for segmentation and Reassembly.

My message contains

          Beginning of Message
      continuation of message and

      end of message</code></pre><p>Messages are not coming in sequence and based on sequence number and message id i need to reassemble.</p><p>I dont know whether i should use</p><pre><code>          conversation or

      add_fragment_seq_next or

      add_fragment_seq_check</code></pre><p>Please suggest. I got stuck with this for long time.</p></div><div id="question-tags" class="tags-container tags"><span class="post-tag tag-link-pdcp" rel="tag" title="see questions tagged &#39;pdcp&#39;">pdcp</span> <span class="post-tag tag-link-layer" rel="tag" title="see questions tagged &#39;layer&#39;">layer</span> <span class="post-tag tag-link-pdu" rel="tag" title="see questions tagged &#39;pdu&#39;">pdu</span></div><div id="question-controls" class="post-controls"></div><div class="post-update-info-container"><div class="post-update-info post-update-info-user"><p>asked <strong>16 Feb '15, 02:17</strong></p><img src=";d=identicon&amp;r=g" class="gravatar" width="32" height="32" alt="umar&#39;s gravatar image" /><p><span>umar</span><br />

accept rate: 0%

You are giving to little information for us to be able to help you. Wireshark has a dissector for 3GPP TS 36.323 PDCP googling there is also 3GPP TS 25.323. The RFC you reference deals only with header compression… If the messages are not comming in sequence there should be a sequence number in them I suppose and of course you need to use that for reassembly.

(16 Feb ‘15, 07:08) Anders ♦

Hi anders thank you very much for your reply. Actually iam using sequence number for reassembly. my fragment table is always returning NULL value. I have posted my code here and yet to get reply. Can you have a look please. I have gone through many example code in epan library but could not find anything. Don’t know why my frag_head is empty. Please help . Thanks

(16 Feb ‘15, 08:34) umar

One Answer:


For reference, the answer was given in this wireshark-dev mailing list thread

answered 17 Feb '15, 03:23

Pascal%20Quantin's gravatar image

Pascal Quantin
accept rate: 30%