2.3.6 IP over Cable Data Network (ipcdn)

NOTE: This charter is a snapshot of the 49th IETF Meeting in San Diego, California. It may now be out-of-date. Last Modified: 13-Oct-00


Richard Woundy <rwoundy@cisco.com>
Andrew Valentine <a.valentine@eu.hns.com>

Internet Area Director(s):

Thomas Narten <narten@raleigh.ibm.com>
Erik Nordmark <nordmark@eng.sun.com>

Internet Area Advisor:

Thomas Narten <narten@raleigh.ibm.com>

Mailing Lists:

General Discussion:ipcdn@ietf.org
To Subscribe: http://www.ietf.org/mailman/listinfo/ipcdn
Archive: ftp://ftp.ietf.org/ietf-mail-archive/ipcdn

Description of Working Group:

The IETF IPCDN Working Group develops and standardizes SNMP MIBs for IP-capable data-over-cable systems, for example cable modems and associated cable-data equipment in a Headend. These MIBs cover not only cable data interfaces, but also management of cable-data equipment and systems.

The WG is also a forum for discussion of Internet-related issues in data-over-cable equipment and systems. In the event of a particular new Internet technology issue arising in the cable-data context, the WG will identify whether that is best handled within the IETF or is best handled by another standards body. In the event that new IETF work is identified, such items MAY be added that to the WG's charter, subject to normal IETF processes. Standardisation of MIBs for the EuroModem cable modem is within the scope of the IPCDN Working Group. Harmonisation of EuroModem MIBs and DOCSIS MIBs is desirable and will be examined by the IPCDN WG.

The IPCDN WG will also keep informed on what other groups in the industry are doing as it relates to the work of this working group.

Related groups:

The IEEE 802.14 WG was chartered to specify the physical layer and data link layer protocols for the CATV Data Network. The IEEE has discontinued the IEEE 802.14 effort, so that group no longer exists.

DOCSIS has completed its 1.0 versions of Data over Cable standards and is in the process of refining these standards to add additional functionality and to repair any flaws discovered in operational use. The IPCDN WG will update the documents produced which track the 1.0 versions accordingly. These include the RF Interface MIB and the Cable Device MIB. In addition, the operational and management issues of multicast over a Cable Data Network will be addressed.

Work items:

The IPCDN WG will address issues related to network management, especially as they concern HFC access networks. It is expected that other services (i.e. RSVP, IPSEC, etc.) will operate mostly unmodified.

- a MIB for managing the Telephone Modem Return Path (Telco Return) for 1-way cable modems. (draft-ietf-ipcdn-tri-mib-01.txt)

- a MIB for managing the Baseline Privacy system for DOCSIS. (draft-ietf-ipcdn-bpi-mib-01.txt), (draft-ietf-ipcdn-bpiplus-mib-00.txt)

- a MIB for managing the Quality of Service parameters for a Cable Data Network. (draft-ietf-ipcdn-qos-mib-02.txt)

- a MIB for managing Multicast (IGMP) over a Cable Data Network. (draft-ietf-ipcdn-igmp-mib-00.txt)

- a MIB for CMTS based customer management (draft-ietf-ipcdn-subscriber-mib-00.txt)

- Revisions to the Proposed Standard RF and CM MIBs to address SNMPv3 and IPv6 compliance and interoperability issues.

Goals and Milestones:

Feb 00


Post final I-D on Baseline Privacy MIB; Last call

Feb 00


Post I-Ds revising RF and CM MIBs to support DOCSIS1.1 and for compliance with SNMPv3 and IPv6

Feb 00


Submit Baseline Privacy MIB to IESG for publication as a Standards Track RFC

Feb 00


Submit updated RF and CM MIBs to IESG with implementation statement for advancement to Draft Standard

Jun 00


Revaluate charter and milestones.


Request For Comments:






Cable Device Management Information Base for DOCSIS compliant Cable Modems and Cable Modem Termination Systems



Radio Frequency (RF) Interface Management Information Base for MCNS/DOCSIS compliant RF interfaces

Current Meeting Report

San Diego, CA
December 13, 2000

Reported by Pak Siripunkaw (psiripunkaw@broadband.att.com)

WG Meeting Summary

Approximately 40 members of the IP over Cable Data Networks WG met at the San Diego IETF on December 13, 2000. The WG agreed to ask the IESG to amend the charter to accept new work items for Euromodem and DOCSIS cable technologies, and to develop an up-to-date work schedule. The WG completed its last-call for the BPI MIB, and agreed to start WG last-calls for the Euromodem NIU Device MIB, the DOCSIS QoS MIB, and Application of the IGMP MIB (RFC 2933) to DOCSIS Devices in the month of January. Since the last IETF meeting, the WG produced one new internet-draft, and five updates to existing internet-drafts.

WG Charter revision (Richard Woundy)

Richard Woundy discussed clarifying the WG charter to differentiate between DOCSIS 1.0 and 1.1. At the present time, the charter refers to the "refining" of DOCSIS 1.0, without mentioning DOCSIS 1.1 technology and the subsequent WG action items. Richard also discussed clarifying the WG charter to support DVB/Euromodem cable technology.

For the DOCSIS 1.0 effort, the WG agreed to drop the effort to standardize the Telco-Return MIB. There are only one or two telco-return cable modem vendors, and the industry is losing interest in telco-return technology.

For the DOCSIS 1.1 effort, the WG agreed to ask to add event notification and account management to the list of WG action items.

For the Euromodem effort, the WG agreed to ask to add the NIU Interface MIB, the INA DVB Interface MIB, and the INA DVB Device MIB to the list of WG action items.

EuroModem NIU Device MIB (Andrew Valentine)

Andrew Valentine discussed the recent changes to the Euromodem NIU Device MIB. The MIB has a new object to disable and enable upstream/downstream multicast. The MIB has dropped the auto-population of anti-spoofing filters, in favor of objects similar to the docsDevCpe objects in the DOCSIS Cable Device MIB. The MIB clarifies the descriptions of NAT-related objects.

The WG expressed support in taking the internet-draft to WG last-call, with no opposition. Note: the WG tends to have more vocal opinions about DOCSIS issues than DVB/Euromodem issues.

DOCSIS QoS MIB (Richard Woundy presenting for Michael Patrick)

Richard Woundy presented a slide from Michael Patrick that enumerated the changes from the qos-03 to the qos-04 drafts. In addition, it was noted that recent email on the mailing list should lead to a few minor textual clarifications to the qos-04 draft.

The WG expressed support in taking the internet-draft to WG last-call, with no opposition.

DOCSIS Cable Device Trap Definition (Junming Gao)

Junming Gao presented slides to explain his new internet-draft on the Cable Device Trap MIB (also known as the Event Notification MIB for DOCSIS 1.1). The new draft defines a uniform set of 28 traps for DOCSIS cable devices.

The WG suggested using the word "notification" rather than "trap", since notifications can refer to either SNMP Trap and Inform PDUs.

The WG suggested using sub-identifier "0" on the object OIDs in the notification objects, e.g. "docsDevEvLevel.0" instead of "docsDevEvLevel".

Some WG members expressed concern that there could be scalability problems with large number of notifications that might be generated by the CM or CMTS devices, and that there should be notification throttling mechanisms. Other WG members pointed out that there were Trap throttling requirements and management objects in the DOCSIS Cable Device MIB (RFC 2669), which seemed satisfactory to the WG.

The WG suggested adding a "switch" that would enable Trap versus Inform PDUs.

The WG strongly suggested using "ifIndex" rather than the CMTS MAC address in the CMTS notification objects.

Junming stated that he was going to change the names of some of the notification objects that were somewhat ambiguous. In particular, the "Res" (Response) object names were changed to "Rsp" names.

Subscriber Management MIB (Richard Woundy)

Richard Woundy stated that the co-author had received no comments on the Subscriber Management MIB. Richard solicited input from the WG whether the document was ready for WG last-call.

Some WG members were concerned about the implementation complexity of this MIB, and a few members suggested that the WG drop this MIB. Other WG members reminded the WG that cable operators did see value in the implementation of this MIB on CMTSs, particularly due to concerns that cable subscribers may bypass the controls in the DOCSIS Cable Device MIB (RFC 2669) with the advent of CPE-Controlled Cable Modems (CCCMs). Most WG members felt that there was not a clear mapping of cable operator requirements to the Subscriber Management MIB in its current form.

Richard suggested that a set of WG members solicit and document the set of cable operator requirements for subscriber management, and that the WG evaluate the current MIB against the requirements. Pak Siripunkaw (psiripunkaw@broadband.att.com) agreed to lead the effort to develop a minimal set of requirements; Azlina Palmer and Kirk Friedman volunteered to help. Other WG members may contact Pak to contribute to this effort.

Proposed RFC 2669 and 2670 updates (Richard Woundy)

Richard Woundy presented slides to document the updates required to the DOCSIS Cable Device and RFI MIBs (RFCs 2669 and 2670). Richard is in the process of getting the internet-draft sources from Michael StJohns, who is working on other projects.

Some WG members pointed out that the Cable Device MIB update should account for new CMCI interfaces such as USB. In particular, it is very desirable to have a simple MIB mechanism to identify all CMCI interfaces within a single row of Cable Device MIB table. This mechanism allows cable operators to produce common DOCSIS configuration files, which often contain implied SNMP Set operations on the Cable Device MIB.

Some WG members pointed out that the RFI MIB update should contain two object updates for EuroDOCSIS support. Richard had identified an update to the "interleaving" object to add a value for the interleaving mode used for EuroDOCSIS modems. Clive Holborow identified a new object to identify whether Annex A, B, or C from ITU-J23 is used for downstream transmission.

Richard suggested that he could produce new internet-drafts by January, assuming he gets the internet-draft sources.

BPI MIB (Richard Woundy)

Richard Woundy presented slides to describe the latest changes to the BPI MIB, based on input from the IETF MIB doctors.

The document completed WG last-call at the meeting with WG approval and no objections.

BPI+ MIB update (Kaz Ozawa)

Kaz Ozawa presented slides to describe the latest changes to the BPI+ MIB, to show the DOCSIS compatibility matrix for the BPI/BPI+ MIBs (e.g. a DOCSIS 1.1 CM needs to support both the BPI MIB and the BPI+ MIB for backward-compatibility), and to enumerate the open issues with the BPI+ MIB.

A particular WG concern (at the meeting and on the mailing list) has been that a DOCSIS 1.1 CMTS supports only the BPI+ MIB, when the downstream CMs might support either the BPI MIB (for DOCSIS 1.0 CMs) and/or the BPI+ MIB (for DOCSIS 1.1 CMs). The intention of the BPI+ MIB is that its CMTS objects permit management of both BPI and BPI+ conversations with downstream CMs. The BPI+ MIB already includes a superset of the BPI MIB objects. A lingering WG concern is that key BPI+ MIB tables (the CMTS TEK table, and the CMTS Multicast Mapping and Authorization tables) use the DOCSIS/BPI+ Security Association ID (SAID), whereas associated BPI MIB tables use the DOCSIS Service ID (SID). Unfortunately, the SAID values may overlap the SID values for a single DOCSIS 1.1 CMTS -- in theory. The current BPI+ MIB approach is to define the CMTS SAID objects to contain SAID values for DOCSIS 1.1 CMs and to contain SID values for DOCSIS 1.0 CMs. Richard Woundy suggested that a DOCSIS 1.1 ECR is needed, to mandate uniqueness of the combined SID/SAID value range, that he will justify in a future email to the ipcdn and docsis mailing lists. This issue needs to be resolved before WG last-call.

Some WG members expressed concern that the BPI+ MIB combines management of the DOCSIS BPI+ protocol with the management of secure software download. The WG consensus was that although the functionality could be split into two documents in theory, the WG could approve a single document that tackles both management concerns.

One of the BPI+ MIB object names changed in the most recent version. The WG pointed out that changing an object name requires defining a new OID for the object.

The IETF MIB doctors will require IPv6 support in the BPI+ MIB (BPI MIB narrowly missed the requirement). Richard suggested that the BPI+ MIB should import the generic address object from RFC 2851. Richard also suggested that the BPI+ MIB IP multicast address should be coupled with an IP address mask, rather than an IP address prefix (as is the case in both the BPI and BPI+ MIBs), for better support of IPv6 multicast groups. Richard will explain his rationale in a future email to the ipcdn mailing list.

Application of the IGMP MIB to DOCSIS (Richard Woundy for Howard Abramson)

Richard Woundy presented slides from Howard Abramson to describe the changes to this specification, which explains how the IGMP MIB (RFC 2933) applies to DOCSIS 1.1 devices.

The WG expressed support in taking the internet-draft to WG last-call, with no opposition.

Requirement for Account Management control (via MIB)

The WG expressed support for a new effort for a MIB to control DOCSIS accounting management. The working assumption is that the MIB controls the CMTS accounting mechanisms, but does not contain object tables which represent the actual counter values (i.e. accounting information would not be retrieved from the CMTS using SNMP PDUs).

Kirk Friedman volunteered the services of the DOCSIS Account Management group to build a set of initial requirements. Kirk and Azlina Palmer volunteered to help.


BPI+ MIB Update
DOCSIS 1.1 IGMP MIB Application Note
QOS MIB 04 Updates
EuroModem MIB Draft 01
Cable Device Trap MIB
Proposed RFC 2669 and 2670 Updates