Ethereal-users: Re: [Ethereal-users] LDAP and short frames

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From: Guy Harris <guy@xxxxxxxxxxxx>
Date: Wed, 3 Sep 2003 12:49:59 -0700

On Wednesday, September 3, 2003, at 12:08 PM, Distribution Lists wrote:

I'm seeing a fair amount of short frame during some LDAP binds/search.
What are short frames

The consequence of either

1) when capturing, specifying a "snapshot length" not large enough to capture the entire packet;

2) possibly not enabling LDAP-over-TCP reassembly (although those should show up as something other than a "Short Frame", e.g. "Malformed Packet" or "Unreassembled Packet");

3) some weird interaction between some VPN/etc. drivers on Windows and WinPcap, that causes an effect similar to 1);

	4) some bug in Ethereal.

At the beginning of the detailed view of each packet it should say something such as

	Frame N (M bytes on wire, P bytes captured)

If P is less than M, it's either 1) or 3).

If it's neither 1) nor 3), then select "Preferences" from the Edit menu, open up the "Protocols" list in the Preferences dialog box, select "LDAP", and make sure that "Desegment all LDAP messages spanning multiple TCP segments" is turned on. If it's not, turn it on, and click "OK".

If that makes the problem go away, it's 2). If it doesn't make the problem go away, it's 4).

 and are they hindering performance ?

They don't represent any real behavior on the wire, they represent an artifact of the way the packets are being captured or dissected by Ethereal.

I can send the trace in text...but its verbose

A binary version of the trace would be better. If the problem is 4) rather than 1), 2), or 3), send us that.