Subject: GSE Zero Length PDU

From: "Kevin Kimmich" <[email-masked]>
Date: Fri, 28 Mar 2008 11:31:13 -0400

Hello,

We're in the process of defining a system that will use GSE.

We are looking at cases that are ambiguous in the GSE specification. One
such case is how to deal with zero length PDUs. It's possible, though
probably not advisable, for an encapsulator to send such a packet.

Any advice on how to handle this case?

Thanks,

Kevin Kimmich

Senior Software Engineer

Efficient Channel Coding, Inc.

The University of Aberdeen is a charity registered in Scotland, No SC013683.

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From: Bernhard Collini-Nocker <[email-masked]>
Date: Sat, 29 Mar 2008 17:56:51 +0100

Hello (again),

Kevin Kimmich schrieb:
> Hello,
> 
> We’re in the process of defining a system that will use GSE.
> 
> We are looking at cases that are ambiguous in the GSE specification. 
> One such case is how to deal with zero length PDUs. It’s possible, 
> though probably not advisable, for an encapsulator to send such a 
> packet.

on one side a zero length PDU (interpreted as having a valid protocol
header but empty payload) is not a "problem" for GSE rather than the
upper layer protocol(s) that handles the PDU. As long as the
GSE-Protocol-Type field is valid it will pass this "problem" to the
upper layer indicated by Protocol-Type.

On the other side (interpreting zero length PDU as having no header at
all) GSE would need a special Protocol-Type value to support transport
of it (nothing?). Currently only the test-extension-header (see RFC
4326, 5.1) could support this, but would prevent a receiver from
forwarding this (non-existing) data...

> Any advice on how to handle this case?

Combining this with your next question (DOCSIS over GSE) I would assume
that signalling is being carried in DOCSIS frames (as GSE PDUs) that
have only a header but no payload, in what case the first of above
options should work.

> Kevin Kimmich

Regards,
Bernhard