Subject: [ipcdn] IPCDN meeting minutes from Minneapolis

From: Rich Woundy <[email-masked]>
Date: Sun, 08 Apr 2001 22:03:27 -0400

Folks,

Below are the current meeting minutes from the IPCDN WG meeting in 
Minneapolis held on March 19, 2001.

Thanks to Pak Siripunkaw for collecting this information!

Please send any corrections of the minutes to myself and the mailing list 
by Wednesday, April 11, since I need to submit these minutes to the IETF 
folks for permanent archival very soon.

-- Rich

IETF IPCDN Meeting
Minneapolis, MN
March 19, 2001

Reported by Pak Siripunkaw ([email-masked])

WG Meeting Summary
------------------

Approximately 35 members of the IP over Cable Data Networks WG met at the 
Minneapolis IETF on March 19, 2001. The WG discussed the status of most of 
its work items as well as the ongoing charter revision. The WG also 
discussed the common problems with respect to TCP port filtering and 
matching that exist in many of the WG documents.  Since the last IETF 
meeting, the WG submitted two new internet-drafts (not including two drafts 
that missed the submission deadline but were posted to the mailing list), 
and six updates to existing internet-drafts.

WG Status and Charter Revision (Richard Woundy)
-----------------------------------------------

Richard Woundy discussed the overall status of work items in the working 
group. The BPI MIB has been published as RFC 3083, the Euromodem/DVB NIU 
MIB is in WG last-call, and the DOCSIS QoS MIB and Application of the IGMP 
MIB (RFC 2933) to DOCSIS Devices are about to start WG last-call.

It is unclear whether the Application of the IGMP MIB is implemented in a 
DOCSIS device yet. The MIB is required to be implemented for DOCSIS 1.1 
certification, though.

A presentation for the DOCSIS QoS MIB was not available for the meeting, 
but the WG consensus appeared to be in favor of bringing this document to 
WG last-call.

There has been little progress on the proposed Account Management Control 
MIB since the last WG meeting. The WG may want to re-evaluate this project 
as a work item, possibly dropping it.

The next IPCDN meeting is sometime during the week of August 5-10 in 
London, and a number of work items need to be completed by that time.

The co-chairs have been formulating and proposing significant changes to 
the WG charter, to update the description (add text about DOCSIS 1.1 and 
Euromodem), modify work items, and revamp the overall schedule. The charter 
is currently under evaluation by our Area Directors.

EuroModem NIU Device and Interface MIBs (slides by Andrew Valentine)
--------------------------------------------------------------------

Richard Woundy presented slides from Andrew Valentine, which discuss the 
Euromodem NIU Device MIB version -03 -- currently in WG last-call. Richard 
Woundy has submitted editorial comments to the author. Andrew plans to 
collect all comments from the last-call period, issue draft -04, republish 
with a one week review time, and submit to the IESG as a standards track 
specification. The WG raised no technical objections with the draft at this 
meeting.

Andrew also has submitted the first version of the Euromodem NIU Interface 
MIB, which organizes DVB-specific interface management objects into MAC 
layer, RF downstream, and RF upstream groups. There are some analogies 
between this MIB and RFC 2670, particularly in the handling of the 
interface layering model.

EuroModem INA Device and Interface MIBs (slides by Andrew Valentine)
--------------------------------------------------------------------

Richard Woundy presented slides from Jens Pedersen, which discuss the first 
versions of the Euromodem INA Interface MIB and the Euromodem INA Device 
MIB. The INA Interface MIB defines DVB-specific interface management 
objects for MAC layer, RF downstream, RF upstream, and NIU provisioning and 
management. The INA Device MIB defines optional object groups for 
management of general device control, network management access, software 
images, DHCP relay configuration, event handling and logging, Ethernet and 
IP filters, and NIU IP address and subnet controls.

DOCSIS Application of RFC 2933 MIB (slides by Howard Abramson)
--------------------------------------------------------------

Richard Woundy presented slides from Howard Abramson, which discuss changes 
in version -02 of the DOCSIS Application of the IGMP MIB. In this version, 
the author clarifies "interface robustness" for the CM HFC interface (i.e. 
it controls the number of retransmissions of Unsolicited Membership Reports 
in the absence of a response), emphasizes that igmpCacheIfIndex is a table 
index, and clarifies the behavior of the "IGMP cache" when a row is deleted 
(i.e. the row may be recreated upon receipt of a new IGMP Membership 
Report). The WG raised no technical objections with the draft at this meeting.

Subscriber Management MIB (slides by Wilson Sawyer)
---------------------------------------------------

Richard Woundy presented slides from Wilson Sawyer, which discuss changes 
in version -03 of the Subscriber Management MIB, as well as justification 
for its current form. The major change in version -03 is alignment of the 
MIB with RFC 2851 for Internet address-related objects; the specification 
also takes care not to mandate IPv6 capability for MIB compliance.

In the last WG meeting, some folks voiced their concerns about the 
implementation complexity of this MIB. Wilson provides three justifications 
for the current MIB content: (1) multiple vendors are implementing this MIB 
(which suggests the MIB is implementable), (2) CableLabs requires 
implementation of this MIB for DOCSIS 1.1 certification, and (3) the 
filtering functionality and source address verification are needed for the 
protection of the cable network.

The WG expressed confusion about the OID for the base of the Subscriber 
Management MIB subtree. While "{ experimental 83 4 }" is the current OID, 
the current text suggests that the OID would be modified to "{ docsDev 4 
}". Unfortunately, Mike StJohns already assigned this OID to 
docsDevConformanceV2 in the RFC 2669 update. The WG co-chairs will assign a 
new OID for the Subscriber Management MIB -- in all likelihood, "{ docsDev 
5 }".

Some WG members have sent technical issues to the author and/or the mailing 
list, which should be resolved. One technical issue, concerning TCP traffic 
filtering and IP fragmentation, was discussed separately since it broadly 
applies to a number of WG specifications (see below).

DOCSIS Notifications (slides by Junming Gao)
--------------------------------------------

Richard Woundy presented slides from Junming Gao, which discuss changes in 
version -01 of the DOCSIS Notification MIB. In this version, the author 
adheres to RFC 2576 by adding "0" to key OID prefixes, adds trap control 
objects, adds a reference to the event throttling control of RFC 2669, and 
modifies some object names for clarity.

The WG discussed whether the event throttling mechanism of RFC 2669 applied 
to events not defined in this internet draft. The WG agreed that the 
mechanism also applies to generic SNMP traps such as linkUp and linkDown.

RFC 2669 and 2670 Updates (Richard Woundy)
------------------------------------------

Richard Woundy presented slides which discuss the latest updates to the 
DOCSIS Cable Device MIB and the DOCSIS RFI MIB (RFCs 2669 and 2670). In 
version -01 of the update to RFC 2669, the author aligns the MIB with RFC 
2851 for most Internet address-related objects, adds an object to support 
the DOCSIS Application of RFC 2933 MIB, and adds references to the Event 
Notification and Subscriber Management MIBs. Future work includes aligning 
this MIB with the DOCSIS QoS MIB and the DOCSIS OSSI specification, 
choosing one mechanism to support multiple CPE-side interfaces on a CM 
(DOCSIS OSSI approach versus InterfaceSet objects), clarifying the handling 
of generic traps, and fixing issues with the docsDevNmAccessTable.

In the first version of the update to RFC 2670, the author aligns Internet 
address-related object with RFC 2851, modifies objects and compliances for 
EuroDOCSIS and European cable plant characteristics, clarifies object 
descriptions for objects with the BITS syntax, and fixes other object 
definition errors. Future work includes aligning this MIB with the DOCSIS 
Notification MIB (i.e. adding objects from IF-EXT-MIB), clarifying the 
upstream channel transmit timing offset, and aligning with the most recent 
version of the Interfaces Group MIB, RFC 2863.

The WG felt that generic traps (e.g. linkUp and linkDown) should be 
included in the RFC 2669 throttling control.

A WG member suggested that the WG determine the extent of the overlap 
between the RFC 2669 event log and RFC 3014, "Notification Log MIB".

A WG member suggested that RFC 2669 may need more objects for maximum CPE 
limits. One object might indicate how many CPE devices the CM can support 
in firmware; another object might indicate the maximum number of CPE 
devices that should be allowed to communicate across the cable network by 
operator configuration.

A WG member pointed out that the docsDevEvReporting object uses the BITS 
syntax, which needs to be clarified (i.e. bit-ordering) in the description.

A WG member pointed out that slide 8 made reference to RFC 2683, a typo for 
RFC 2863. This is corrected in the powerpoint slides submitted to the IETF.

A WG member notes that the Interfaces Group MIB, RFC 2863, now has a 
companion specification, The Inverted Stack Table Extension to the 
Interfaces Group MIB, RFC 2864. The author agreed to investigate the impact 
on RFC 2670.

Pak Siripunkaw agreed to help Rich reconcile the RFC 2670 update with the 
DOCSIS OSSI.

TCP Port Filtering Issues (Richard Woundy)
------------------------------------------

Richard Woundy presented slides on potential issues with TCP port filtering 
and matching in various WG work items. RFC 1858 describes problems related 
to IP fragmentation and TCP port filtering, and some implementation 
workarounds. Richard recommends that cable device implementations 
performing TCP/UDP port filtering should ignore non-initial IP fragments, 
but should drop all TCP fragments with offset 1, to prevent tiny-gram and 
port-overwrite attacks. Richard also recommends that cable device 
implementations performing TCP port matching (e.g. DOCSIS QoS MIB) should 
not match non-initial IP fragments, and applications requiring special 
handling should use Path MTU Discovery (RFC 1191).

The WG agreed that this is a problem that needs to be fixed immediately.

After the WG session, a WG member pointed out that RFC 1858 offers another 
workaround for TCP port filtering: a forwarding device can reassemble the 
IP fragments before applying the port filters and forwarding the datagram. 
His suggestion was to allow this implementation workaround as an alternative.

<end of minutes>

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