Dear Thomas,
Dear Benoit, all,
Why don't we make the chunk
elements by default variable length and just don't allow them to be
fixed length??
I see a drawback with this approach. I have to specify in [PSAMP-PROTO]
that all chunk elements will be encoded with variable length I.E..
Fine, I can list all the ones that exist today. But what about the new
ones, administered by IANA. How do we know that these are chunk
elements or not? We could say: if it contains "Section" part of the
name, this is a chunk, so encoded with a variable length -> this is
a little bit light! Alternatively, we could specify in the I.E.
description that it must be encoded with a variable length but it break
the independence of the information model versus the protocol.
Regards, Benoit.
Regards,
Thomas
--
Thomas Dietz E-mail: Thomas.Dietz@netlab.nec.de
Network Laboratories Phone: +49 6221 90511-28
NEC Europe Ltd. Fax: +49 6221 90511-55
Kurfuersten-Anlage 36
69115 Heidelberg, Germany http://www.netlab.nec.de
BTW, regarding [PSAMP-INFO], the 2 ipHeaderPacketSection and
ipPayloadPacketSection information element descriptions currently
contain:
"If insufficient octets are available,
the remainder of the data should be zero-filled and an additional
information element sent (e.g., ipPayloadLength) indicating how
much of the data is valid."
Obviously these sentences will have to be removed.
Regards, Benoit.
Dear all,
>From the Vancouver meeting minutes:
Open Issue (not numbered): Chunk with too short length
How to encode "chunk" with a too short length? Padding wouldn't be
recognized
by the collector. One solution would be using a new template for each
length.
Proposal: The protocol draft should say that padding MUST NOT be used
for
variable length IEs.
Here is a new proposed text (actually, only the second paragraph is new)
Basic Packet Report
For each selected packet, the Packet Report MUST contain the following
information:
- The associationsId Information Element
- Some number of contiguous bytes from the start of the packet,
including the packet header (which includes link layer, network layer
and other encapsulation headers) and some subsequent bytes of the
packet payload. Alternatively, the number of contiguous
bytes may start at the beginning of the payload. The
Layer2PacketSection, l2PayloadPacketSection, mplsLabelStackSection,
mplsPayloadPacketSection, ipPacketSection, and ipPayloadPacketSection
PSAMP Information Elements are available for this use.
- The input sequence number(s) of any Selectors that acted on the
packet, represented by the selectorInputSequenceNumber Information
Element.
The contiguous Information Elements (Layer2PacketSection,
l2PayloadPacketSection, mplsLabelStackSection,
mplsPayloadPacketSection, ipPacketSection, and ipPayloadPacketSection)
MAY be encoded with a fixed length field or with a variable sized
field. If one of these Information Elements is encoded with a fixed
length field whose length is too long for the number of contiguous
bytes in the selected packet, padding MUST NOT be used. In this case,
the Exporting Process MUST export the information either in a new
Template Record with the correct fixed length field, or either in a new
Template Record with a variable length field.
Feedback?
Regards, Benoit.
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