OPS Area
PSAMP WG Meeting Minutes
IETF #57
July 17, 2003
Minutes by Andy Bierman
Review Material
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A) draft-ietf-psamp-framework-03.txt
B) draft-ietf-psamp-sample-tech-02.txt
C) draft-ietf-psamp-mib-00.txt
Agenda
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1) WG Status
2) Sampling Framework Issues
3) Packet Selection Issues
4) Report Format and Export Protocol
5) PSAMP MIB
Minutes
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1) WG status
The milestones for the working group were presented and briefly
discussed:
Initial Final Draft Draft Description
----------------------------------------
------------------------------
Done May 03 PSAMP Framework
Done May 03 Packet Selector and Packet Information
Feb 03 Sep 03 Report Format and Report Stream Format
Mar 03 Oct 03 Export Protocol and Requirements for
Collectors
Done Nov 03 PSAMP MIB
The report format and export protocol documents are behind schedule
because the working group decided to use the mechanisms developed by the
IPFIX WG for these purposes. The IPFIX WG is not scheduled to complete
these documents until the end of the year.
2) Sampling Framework Issues
The Framework draft (A) was discussed by the group.
2.1) Terminology
Some clarifications are needed in PSAMP terminology:
- PSAMP device is not a precise enough term
- need clarification between filtering and sampling. Distinction is not
always clear (e.g., hashing)
2.2) Conformance
It is not clear where specific conformance requirements should be
specified. It is likely that requirements related to a portion of PSAMP
covered by another document, such as packet selection or report export,
should be moved to that document.
Some packet report requirements were discussed, such as
- packet reports must contain:
- first N bytes
- report sequence number
- administrative details (selector ID)
The congestion avoidance requirement for the export process was
discussed briefly. There is a desire to meet this requirement in a way
that is not too burdensome on PSAMP devices.
The requirements for the PSAMP MIB were briefly discussed. These include
some mandatory configuration objects and some optional (additional)
complex configuration objects, for such features as multiple selectors and
filtering.
Security requirements were also discussed. There is a need for secure
export, which includes:
- confidentiality
- integrity
- authentication of sender
- secure configuration
2.3) Open Issues
There may be a need to make adjustments to the document for better
alignment with IPFIX terminology. There are some minor sections (such as an
overview of configuration) that need to be completed. The group agreed
that the current draft is ready for WG Last Call.
3) Packet Selection
The Packet Selection draft (B) was discussed by the group. Updates since the
last draft were presented. Refer to the slides for the details of that
presentation. The significant changes made since the last draft
include:
- better alignment with the framework draft
- description of packet selection schemes updated
- conformance changed so that one scheme must be supported but which one
is up to the implementor
- concepts of filtering and sampling aligned with framework
- listed sampling techniques and parameters
The group was asked if the current list of packet selection schemes is
sufficient and there was agreement it is sufficient.
3.1) Open Issues
There are some details that need to be added to the document, such as a
description of hash-based sampling. The information model details will be
moved to the report format document. Details about which hash
functions also needs to be resolved. A mechanism for defining high level
filter specifications is needed. There is some terminology that could be
better aligned related to the IPFIX metering process. It is expected that
the next draft will be ready for WG Last Call.
4) Report Format and Export Protocol
A presentation on the IPFIX Report and Export protocol was given. Refer to
the slides for details. The IPFIX Information Model and IPFIX Protocol
documents are relevant to the PSAMP report format and export protocol, and
should be read by the working group.
4.1) Open Issues
Separate documents are needed for the PSAMP Information Model and PSAMP
usage of the IPFIX protocol. These documents will rely on the IPFIX
documents, and only add enough details to support unambiguous
conformance for PSAMP purposes. These documents are expected to be
started before the next IETF meeting in November 2003.
5) PSAMP MIB
A presentation on the PSAMP MIB was given. Refer to the slides for
details. The MIB structure follows the structure of the framework and
packet selection mechanisms. There is a group describing packet
selection methods. For each method, there are objects which report the
type, capabilities, and configured parameters.
There is a reporting group used to configure the addresses of the report
collectors. There is an instance group, which identifies the specific
active sampling/reporting processes that are active on the PSAMP device.
There is a group that identifies the sampling methods supported by the
device. This needs to better align with the framework and packet
selection terminology and selection methods.
5.1) Open Issues
The following open issues were identified:
- Information about Filtering and Sampling Reports is currently not
included
- Several sampling methods are not yet defined
- Packet filtering needs to be added to sampling methods
- The parameter set definition of sampling methods needs to be checked
carefully, some capability definitions are not yet complete.
- Conformance statement and security considerations needed
- Row status objects in writable tables needed
- Support for reporting to multiple collectors needed
- Some descriptor name lengths exceed SMI recommendations
Two issues were resolved at the meeting:
- Should there be support for more than two sampling parameter sets per
instance? The group decided two sets is sufficient.
- Should there be a single object for capabilities, using BITS syntax, or
should there be multiple boolean objects, as in the current draft? The
group decided one BITS object would be better.
A new draft of the PSAMP MIB is expected about six weeks after the IETF
meeting.
6) Proposal on per-packet record export
There was some time left at the end of the meeting, so a
presentation was added which proposes to add per-packet fields to the
IPFIX (or PSAMP) information model. Some new features, such as
additional filtering of reports based on packet contents and a global
packet ID were requested.
There was some objection to addressing this work in the PSAMP WG and
concern about the significant resources that would be required on a PSAMP
device to support these features.
Note that packet selection is not affected, just the report process is
impacted by this proposal. Instead of the first N bytes, an export
process would have to extract named fields and maybe apply filters
against the payload, to determine which fields to include in the report.
Nobody in the group said they needed these reporting features. It was
suggested that RMON filtering should be used for packet content
filtering. This proposal may be discussed further on the WG mailing list.
It is possible that the information model additions can be done
independently of the current PSAMP effort.
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