Wireshark-dev: Re: [Wireshark-dev] [PATCH] UMTS Frame Protocol: more K12/K15 support, Spare Extension fields

From: Kriang Lerdsuwanakij <lerdsuwa@xxxxxxxxxxxxxxxxxxxxx>
Date: Sat, 05 May 2007 00:15:01 +0700

Martin Mathieson wrote:

One of the reasons I hadn't added Spare Extension before if that I've never seen it appear in frames in practice, and it sounds as though you had to fake it in order to test your patch? It'll be good to have it for completeness though! Do you happen to know of any equipment that does write out Spare Extension bytes?

I think this Spare Extension is useful to detect when there is a mismatch between the version of FP assumed by dissector and the version actually captured. Looking at Release 7 specification, for example, there is a new field Ext. Propagation Delay added to RACH DATA FRAME (TS 25.425 Figure 9). Using Release 6 dissector this should show up as Spare Extension. (This could be either mean that user hasn't upgrade Wireshark to latest version, or we haven't update FP dissector code to handle newer releases yet.) Such field is flagged as warning in expert information by the patch.

I am not aware of any equipment producing these right now. And yes, the test example

has been edited by hand. But it should be useful down the road.

Best regards

Kriang Lerdsuwanakij