Subject: [L2CP] Draft charter for Layer 2 Control

From: [email-masked]
Date: Thu, 19 Jan 2006 17:19:00 +0100

Dear L2CP'ers,

Here's a first stab at the charter for a new working group that would 
focus on Layer 2 Control.

Some remarks:
- I've put initial focus on the *concept* of Layer 2 Control rather than 
the *protocol* to achieve that concept. This is done in the spirit of 
pitfall 5) described in draft-narten-successful-bof-00.txt 
(Considerations for Having a Successful BOF). Having said that, I've 
also put focus on GSMPv3 as the starting point for protocol work.
- I've assumed that the working group would fall under the umbrella of 
the Internet Area.
- Positions for Chair(s), Technical Advisor(s) and Secretary(ies) are 
left open
- Should we somehow refer to the l2cp work performed at the DSL Forum? I 
assume we can only refer to publicly available documents. The only 
document that has been made visible to the IETF is a previous version of 
PD-021v2 (see email on the GSMP exploder, Nov 14, 2004)

Comments are welcome!

Regards,
Sven

Layer 2 Control (l2c)
=====================

Current Status: Non-existing Working Group

Chair(s):
TBD <tbd>
TBD <tbd>

Internet Area Director(s):
Mark Townsley <[email-masked]>
Margaret Wasserman <[email-masked]>

Internet Area Advisor:
Mark Townsley <[email-masked]>

Technical Advisor(s):
TBD <tbd>

Secretary(ies):
TBD <tbd>

Area Specific Mailing List:
[email-masked]

Mailing Lists:
General Discussion: [email-masked]
To Subscribe: [email-masked]
In Body: subscribe your_email_address
Archive: http://www.ietf.org/mail-archive/web/l2cp/index.html

Description of the charter for this WG:

When deploying value-added services across broadband access networks 
(e.g. DSL), special care is required to obtain the desired level of 
quality of service and effective service control. With the introduction 
of so-called "triple play services" (i.e. high speed Internet access, 
voice over IP and broadcast TV / Video on Demand), some means of 
coordination between the different network elements in the access 
network becomes necessary.

Traditionally, the different network elements are usually controlled by 
separate element managers, which are connected to one set of network and 
service management systems. Frequently, organizational boundaries will 
be in place between departments operating the local loop, the 
access/aggregation network and the IP network. One approach to obtain 
the desired level of coordination would thus be based on the 
introduction of standard business-to-business interfaces between these 
domains. This approach may be a challenging one if real time behavior is 
to be achieved.

The approach that will be considered by this working group consists of 
the introduction of a dedicated control mechanism between an Access Node 
(e.g. a DSLAM) and a Broadband Network Gateway (e.g. a BRAS). This 
concept is called "Layer 2 Control" (l2c), in line with the ideas 
discussed and being worked out by the DSL Forum (cf. PD-021v2 submitted 
to the GSMP exploder on November 14, 2004).

Different applications can be identified where there is a desire for a 
control plane between an Access Node and a BNG in order to perform 
QoS-related, service-related and subscriber-related operations.

Firstly, this working group is responsible for writing the framework and 
requirements for Layer 2 Control. This working group will consider the 
input of the DSL Forum in the definition of the use cases.

Secondly, this working group will investigate a protocol solution to 
achieve "Layer 2 Control" between an Access Node and a BNG for selected 
use cases, including the following:

- Topology discovery
DSL Forum TR-059 identifies various queuing/scheduling mechanisms to 
avoid congestion in the access network while dealing with multiple flows 
with distinct QoS requirements. Such mechanisms require that the BNG 
gains knowledge of the topology of the access network, the various links 
being used and their respective rates. One approach to achieve this is 
to send the characteristics of the local loop (e.g. DSL sync rate) at 
session establishment time. In this case, the characteristics would be 
added to DHCP and/or PPPoE messages by means of newly defined 
sub-options. Another approach consists of sending the information by 
means of a new Layer 2 Control mechanism, independent of the PPP or DHCP 
session. In this case it is possible to take into account the possible 
dynamic nature of the access loop (e.g. when using Seamless Rate 
Adaptation).

- OAM
Traditional DSL broadband access networks employ point-to-point ATM 
circuits between a CPE and a BRAS. In such an environment, 
troubleshooting can be achieved by means of end-to-end ATM loopbacks. 
With Ethernet getting a more important role as layer 2 technology in the 
aggregation network, operators require to keep ways to test and 
troubleshoot connectivity in the case of a mixed Ethernet and ATM access 
network (including the local loop). To reach consistency with ATM based 
broadband access networks, a layer 2 control mechanism can be introduced 
between a BNG and an Access Node, allowing to trigger the OAM mechanism 
used on the local loop.

In the context of PD-021v2, a protocol analysis was performed to find 
the best solution to achieve "Layer 2 Control". PD-021v2 recommends 
achieving these concepts based on the General Switch Management Protocol 
(GSMPv3). It was concluded that the full set of GSMP was not needed to 
drive Layer 2 Control messages, and that GSMPv3 needed to be extended 
with new parameters and message types.

This working group is responsible for investigating which subset of 
GSMPv3 is required for l2c and which extensions are to be specified for 
the selected use cases. It will also respond to protocol issues that 
arise during implementation of the current specifications.

Finally, this working group will investigate possible extensions of the 
above concepts to obtain broader applicability. In this context, the 
following will be addressed:

- Use of l2c over non-DSL access technologies
Alternate broadband access technologies such as PON, Ethernet and Wimax 
will have similar challenges to address. These technologies could 
benefit from the same approach, providing a unified control and 
management architecture for multiple access technologies, hence 
facilitating migration from one to the other and/or parallel deployments.

- l2c support over a lightweight transport
The working group will investigate the possibility of mapping GSMP over 
a lighter transport such as IP or UDP.

Goals and Milestones:

April 2006	Document l2c Framework and Requirements (based on DSL Forum work)
May 2006	Initial WG Internet-Draft defining the subset of the GSMPv3 
protocol and extensions to achieve Topology Discovery, OAM and Line 
Configuration in a DSL environment
August 2006	Submit the l2c Framework and Requirements to IESG for 
Proposed Standard
September 2006	Submit the GSMPv3 extensions to achieve Topology 
Discovery, OAM and Line Configuration in a DSL environment to IESG for 
Proposed Standard
December 2006	Define GSMPv3 extensions for the mapping over a 
lightweight transport mechanism
February 2007	Submit the extensions of GSMPv3 to achieve Topology 
Discovery and Line Configuration in a DSL environment to IESG for Draft 
Standard
March 2007	Define GSMPv3 extensions to achieve Topology Discovery in a 
non-DSL environment (e.g. PON, Wimax)
June 2007	Sumbit the GSMPv3 extensions for the mapping over a 
lightweight transport mechanism to IESG for Proposed Standard
September 2007	Sumit GSMPv3 extensions to achieve Topology Discovery in 
a non-DSL environment to IESG for Proposed Standard
September 2007	Re-charter or conclude Working Group

Internet-Drafts:
GSMP extensions for layer2 control (L2C) - Topology Discovery and Line 
Configuration <draft-wadhwa-gsmp-l2control-configuration-02.txt>

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---

From: Avri Doria <[email-masked]>
Date: Mon, 30 Jan 2006 14:04:10 -0500

Hi,

I have just joined this list and would like make a few comments on  
the proposed charter.  I know I am joining the conversation a bit  
late, but I did not know there was a list already.

> To: l2cp at ietf.org
> Subject: [L2CP] Draft charter for Layer 2 Control
> From: Sven.Ooghe at alcatel.be
> Date: Thu, 19 Jan 2006 17:19:00 +0100
> Dear L2CP'ers,
>
> Here's a first stab at the charter for a new working group that  
> would focus on Layer 2 Control.
>
> Some remarks:
> - I've put initial focus on the *concept* of Layer 2 Control rather  
> than the *protocol* to achieve that concept. This is done in the  
> spirit of pitfall 5) described in draft-narten-successful- 
> bof-00.txt (Considerations for Having a Successful BOF). Having  
> said that, I've also put focus on GSMPv3 as the starting point for  
> protocol work.

I think you have to distinguish between  a WG that is taking a  
problem and casting about for a solution or a group that wants to  
work on a protocol because it has already been worked out.  if there  
has already been a decisions to use a protocol, and if there are  
already implementations/deployments of the protocol being used for  
this function, then it does not seem unreasonable to me to think  
about forming a protocol oriented group as opposed to one that will  
spend the next year or so rehashing the ground that the DSL forum  
already went through to come to the current conclusion.

> - I've assumed that the working group would fall under the umbrella  
> of the Internet Area.

I think you need to be open to the possibility of it being a  
Management & O Area protocol.

> - Positions for Chair(s), Technical Advisor(s) and Secretary(ies)  
> are left open
> - Should we somehow refer to the l2cp work performed at the DSL  
> Forum? I assume we can only refer to publicly available documents.  
> The only document that has been made visible to the IETF is a  
> previous version of PD-021v2 (see email on the GSMP exploder, Nov  
> 14, 2004)

I think so.  Why not build on work done elsewhere?

> ...

> In the context of PD-021v2, a protocol analysis was performed to  
> find the best solution to achieve "Layer 2 Control". PD-021v2  
> recommends achieving these concepts based on the General Switch  
> Management Protocol (GSMPv3). It was concluded that the full set of  
> GSMP was not needed to drive Layer 2 Control messages, and that  
> GSMPv3 needed to be extended with new parameters and message types.
>

I am wondering if you looking at the published RFC or at the latest  
draft draft-ietf-gsmp-v3-base-spec-07 as the base you might decide to  
use.

the primary difference between the PS and the i-d is that it has been  
broken up to be less monolithic, so that adding and modifying  
functions should be easier.

> GSMPv3 is required for l2c and which extensions are to be specified  
> for the selected use cases. It will also respond to protocol issues  
> that arise during implementation of the current specifications.

if you sue draft-ietf-gsmp-v3-base-spec-07 then, opther then perhaps  
adding or changing some of the base feature, most of the work would  
involve creating the technology specifc TLVs for DSL.

>
> Finally, this working group will investigate possible extensions of  
> the above concepts to obtain broader applicability. In this  
> context, the following will be addressed:
>
> Alternate broadband access technologies such as PON, Ethernet and  
> Wimax will have similar challenges to address. These technologies  
> could benefit from the same approach, providing a unified control  
> and management architecture for multiple access technologies, hence  

i think each of these would require a set of technology specific TLVs.

> The working group will investigate the possibility of mapping GSMP  
> over a lighter transport such as IP or UDP.

In one sense this is a good idea.  but only if you add some of the  
congestion control and security functions to gsmp itself.

this has always been a tradeoff.  i do believe there is already an  
Ethernet mapping for GSMP.

> May 2006 Initial WG Internet-Draft defining the subset of the  
> GSMPv3 protocol and extensions to achieve Topology Discovery, OAM  
> and Line Configuration in a DSL environment
> Discovery, OAM and Line Configuration in a DSL environment to IESG  
> for Proposed Standard
> Discovery and Line Configuration in a DSL environment to IESG for  
> Draft Standard
> March 2007 Define GSMPv3 extensions to achieve Topology Discovery  
> in a non-DSL environment (e.g. PON, Wimax)
> September 2007 Sumit GSMPv3 extensions to achieve Topology  
> Discovery in a non-DSL environment to IESG for Proposed Standard
> GSMP extensions for layer2 control (L2C) - Topology Discovery and  
> Line Configuration <draft-wadhwa-gsmp-l2control-configuration-02.txt>

you might want to list draft-ietf-gsmp-v3-base-spec-07