Subject: Draft charter for L2VPN

From: Alex Zinin <[email-masked]>
Date: Wed, 7 May 2003 18:53:40 -0700

Proposed L2VPN charter below (draft).
--
Alex

Layer 2 Virtual Private Networks (l2vpn)

Chairs: <under discussion>

Area Director(s):
   Thomas Narten <[email-masked]>
   Erik Nordmark <[email-masked]>

Area Advisor:
   Thomas Narten <[email-masked]>

Technical Advisor:
   Alex Zinin <[email-masked]>

Description of Working Group:

This working group is responsible for defining and specifying a
limited number of solutions for supporting provider-provisioned
layer-2 virtual private networks (L2VPNs).

The WG is responsible for standardization of the following solutions:

1. Virtual Private LAN Service--L2 service that emulates LAN
   across an IP and an MPLS-enabled IP network.
 
2. Virtual Private Wire Service--L2 service that provides L2
   point-to-point connectivity (e.g. Frame Relay DLCI, ATM VPI/VCI,
   point-to-point Ethernet) across an IP and an MPLS-enabled IP network.

The WG will address intra-AS scenarios only at this point (inter-AS
considerations will be considered for inclusion in the updated
charter when the current one is completed.)
   
As a general rule, the WG will not create new protocols, but will 
provide functional requirements for extensions of the existing 
protocols that will be discussed in the protocol-specific WGs.
As a specific example, this WG will not define new encapsulation
mechanism, but will use those defined in the PWE3 WG.

The WG will work on the following items, adding new work items 
will require rechartering:

1. Discovery of PEs participating in L2 service, and
   topology of required connectivity

2. Signaling of psuedo-wire and service parameters

3. Solution documents (providing the framework for a specific
   solution, should include info on how discovery, signaling,
   and encaps work together, include security, AS as a separate
   document,...)

4. MIBs
   
5. L2VPN-specific OAM extensions--extensions to existing OAM
   solutions for VPLS and VPWS.
   
Milestones (optimistic):

JUL 2003  Submit L2 requirements to IESG for publication as Informational RFC
JUL 2003  Submit L2 framework to IESG for publication as Informational RFC
JUL 2003  Identify VPLS and VPWS solutions for the WG
AUG 2003  Submit an I-D describing MIB for VPLS
AUG 2003  Submit an I-D describing MIB for VPWS
AUG 2003  Submit an I-D on OAM for VPLS
AUG 2003  Submit an I-D on OAM for VPWS
DEC 2003  Submit VPLS solution documents to IESG
DEC 2003  Submit VPWS solution documents to IESG
JAN 2004  Submit MIB for VPLS to IESG
JAN 2004  Submit MIB for VPWS to IESG
MAR 2004  Submit OAM for VPLS to IESG
MAR 2004  Submit OAM for VPWS to IESG

---

From: Yakov Rekhter <[email-masked]>
Date: Mon, 12 May 2003 09:43:57 -0700

Alex,

> Proposed L2VPN charter below (draft).

Assume that there is a (rough) consensus on splitting the PPVPN WG
into two (which is yet TBD), I'd like the following to be added to 
the L2 VPN charter:

   The effort will produce a small number of approaches that are based
   on collections of individual technologies. The goal is to foster 
   interoperability among implementations of a specific approach. 
   Standardization of specific approaches will be gauged on (I)SP support.  

Yakov.

---

From: Eric Rosen <[email-masked]>
Date: Mon, 12 May 2003 13:34:16 -0400

Two  L2VPN  charter issues  that  come up  frequently  are  (a) whether  ARP
Mediation  (for  allowing  IP traffic  on  a  p2p  link between  two  unlike
attachment  circuits) falls  into the  charter,  and (b)  whether IPLS  (for
allowing LAN-like connectivity among a  set of IP routers, without requiring
MAC learning,  BPDUs, etc.)  falls into the  charter.  If there  is actually
going to  be an L2VPN charter, I'd  like to see this  settled, preferably in
favor of including these efforts.

---

From: Alex Zinin <[email-masked]>
Date: Tue, 13 May 2003 10:41:18 -0700

>    Standardization of specific approaches will be gauged on (I)SP support.  

Please state why you believe this should be in the charter and what
exactly your proposed text would mean.

> favor of including these efforts. 

I'd like to see more opinions on this.

Monday, May 12, 2003, 2:59:41 PM, [email-masked] wrote:
> I know that this does not matter to some, but IMHO if this new group
> happens, an indication of the WG cooperation with IEEE 802.1 should be
> part of the charter to add clarity.

Noted. Thanks.

Alex

---

From: "Steven.Wright" <[email-masked]>
Date: Tue, 13 May 2003 16:31:36 -0400

> -----Original Message-----
> From: Alex Zinin [mailto:[email-masked]]
> Sent: Tuesday, May 13, 2003 1:41 PM
> To: [email-masked]
> Subject: Re: Draft charter for L2VPN
>
>

> I'd like to see more opinions on this.

I'd like to see the work in this area - IPLS & ARP Mediation -progressed and
documented in a published RFC. They are not the most widely deployed cases,
but they do exist and  have real network applications.

I do not care which group does the work. Given the current emphasis on
polishing charters, it should appear within the scope of one of them.

Steven Wright

---

From: Matt Squire <[email-masked]>
Date: Wed, 14 May 2003 02:08:16 -0400

> charter when the current one is completed.)

I'd like to include an objective that the VPLS services are transparent 
to higher layer protocols (e.g. really emulated a LAN).  Maybe words like...
"
The WG will drive for solutions that are transparent to higher layer 
protocols such as 802.1D bridging and IP.  Optimizations to a basic 
transparent architecture may be developed to foster more efficient 
transport in special cases (such as IP only transport).  The WG will 
cooperate with IEEE 802.1 to ensure proper interworking of VPLS and VPWS 
solutions with traditional bridging networks.
"

>    and encaps work together, include security, AS as a separate

You mention discovery, signaling, and solutions.  Should we mention data 
plane forwarding in #3?

>    solutions for VPLS and VPWS. >
> Milestones (optimistic):
> 

Seems strange to me that the VPLS solutions come AFTER the MIB and OAM. 
   I would have thought it would go the other way, where we define the 
solution(s) first and the MIB and OAM follow from that.

- Matt

---

From: Giles Heron <[email-masked]>
Date: 14 May 2003 12:20:21 +0000

On Tue, 2003-05-13 at 17:41, Alex Zinin wrote:
[snip]
> I'd like to see more opinions on this.

I'd like to see ARP mediation (or an equivalent means of supporting
unlike attachment circuits) and IPLS being progressed in L2VPN.

Giles

-- 
=================================================================
Giles Heron    Principal Network Architect    PacketExchange Ltd.
ph: +44 7880 506185              "if you build it they will yawn"
=================================================================

---

From: Eric Rosen <[email-masked]>
Date: Wed, 14 May 2003 10:36:55 -0400

Matt> I'd  like  to  include  an   objective  that  the  VPLS  services  are
Matt> transparent to higher layer protocols (e.g. really emulated a LAN) 

I  would  be  opposed to  this  as  a  charter  requirement.  This  kind  of
requirement can  easily get you into a  situation in which you  end up doing
90% of the  work to handle a 1% problem.  Given  a particular solution which
doesn't quite meet this requirement, the WG should be able to decide whether
the solution comes  close enough or not; this  shouldn't be predetermined by
the charter.

---

From: Matt Squire <[email-masked]>
Date: Wed, 14 May 2003 15:25:33 -0400

> the solution comes  close enough or not; this  shouldn't be predetermined by

If this requirement is not met, then we're not really providing a 
virtual X service (X=FR, X=Ethernet, etc.).  If the group is chartered 
to define new service types, and I'm not saying it can't be, thats fine. 
  But a virtual Ethernet wire that requires applications to be aware of 
the virualness of the wire has a high cost of entry.

I'm also not saying that the IPLS isn't applicable.  I had a sentence in 
there that said optimizations for specific applications are allowed. 
And thats what IPLS is - its an optimization of VPLS for IP-only LANs. 
Note its not really a virtual L2 service as there is no "real" service 
that its virtualizing, but it can be useful.  People made IP-only ATM 
LAN implementation doing the same thing, so its been done before and has 
utility.

But the base constructs have to have a goal of transparency.  I can't 
see how we can charter a work effort where the core development is to 
develop virtual services (wire, LAN) that don't have an equivalent 
"real" counterpart. That opens up the door for anything - e.g. it would 
be within the charter to create a virtual Ethernet LAN that uses source 
route bridging.

If we view VPLS as the base construct, and IPLS as an optimization, then 
I see how it fits.  Otherwise, IPLS on its own seems like a new thing. 
There is not "IP only Ethernet" standard, yet its what the document 
attempts to create.

Again, I'm not against IPLS by any means.  But transparency is a very 
useful objective, even if you want to violate it on occassion improve 
efficiency under certain restrictions.

- Matt

---

From: Eric Rosen <[email-masked]>
Date: Wed, 14 May 2003 16:35:55 -0400

The  issue  of  what constitutes  a  virtual  service  arose when  PWE3  was
chartered.  The PWE3 charter states: 

  PWE3 will not strive for pseudo wires to perfectly emulate the
  characteristics of the native service.  For each type of pseudo
  wire, an applicability statement will describe the degree of
  similarity of a pseudo wire to the native service it emulates.

The same should apply to VPLS.

---

From: Ali Sajassi <[email-masked]>
Date: Wed, 14 May 2003 13:56:18 -0700

>but they do exist and  have real network applications.

Steven,

Does Bell South plan to offer VPLS ? If it plans to offer it, then there 
should be no need for IPLS because VPLS can be considered as a super-set 
since it covers both switches and routers as CEs and it supports both IP 
and non-IP traffic. Also inter-operability between IPLS and VPLS is another 
thing to consider if you plan to offer both !! However, if Bell South plans 
to offer IPLS in lieu of VPLS and assumes that all the end-points for a 
transparent LAN service are IPs, then that's a different story.

-Ali

---

From: Muneyoshi Suzuki <[email-masked]>
Date: Thu, 15 May 2003 10:45:23 +0900 (JST)

> > doesn't quite meet this requirement,the WG should be able to decide whether

I agree with Matt.

I think the solution(s) doesn't need to perfectly conform with the original
technology. However, it must not violate the standards for interworking 
with existing implementations. And it must be robust and must not cause 
fatal problems such as loop, blackhole, and flaky PEs.

Thanks,

Muneyoshi Suzuki
Nippon Telegraph and Telephone Corp.

---

From: "Steven.Wright" <[email-masked]>
Date: Thu, 15 May 2003 12:59:05 -0400

Ali,
As I tried to indicate in my  earlier postings, I do NOT regard ARP
Mediation and IPLS as the "ultimate" solution. None-the-less, they provide
well defined features that are scoped, point solutions to particular
customer's problems. And so I believe that we need them documented.
Having two more tools in the toolbox does not invalidate the need for other
solutions with better properties. I have NOT asked for interoperability
between IPLS and VPLS. I suspect IP routing resolves the market requirements
in that area anyway.

Bellsouth already provides  multiple instances of a variety of different
data services within the constraints of different jurisdictions. Application
of a particular protocol in one context does not mean that it is
automatically viable everywhere. Most service providers design a service
considering protocol  constraints, but also considering a variety of other
non-technical factors eg. cost, regulatory treatment, incumbent equipment
capabilities etc. For operational simplicity we prefer a single solution to
a single problem, but our network infrastructure must support solutions to
multiple problems for multiple customers, i.e. we are inherently in a
multiservice environment.

I guess I'm just not sure which of my problems you are suggesting vpls as
the solution to... 8^}

Steven Wright

> From: Ali Sajassi [mailto:[email-masked]]
> Sent: Wednesday, May 14, 2003 4:56 PM
> To: [email-masked]; [email-masked]
> Subject: RE: Draft charter for L2VPN - IPLS & ARP Mediation
>
>
>

---

From: "Cheng-Yin Lee" <[email-masked]>
Date: Thu, 15 May 2003 17:13:25 -0400

If existing routers and bridges cannot expect an emulated LAN service,
and cannot work properly using VPLS, how useful are the solutions then? 
I think it is a requirement that VPLS emulate a LAN (appear as a LAN to
higher layer protocols), otherwise I am afraid the WG may not be
producing useful work.

Regards
Cheng-Yin

---

From: Eric Rosen <[email-masked]>
Date: Fri, 16 May 2003 09:38:33 -0400

Cheng-Yin> If  existing routers and  bridges cannot  expect an  emulated LAN
Cheng-Yin> service, and cannot work properly  using VPLS, how useful are the
Cheng-Yin> solutions then?  

Nobody said  that existing routers  and bridges should  not be able  to work
properly with VPLS.   What is at issue is the extent  to which this requires
absolutely perfect emulation. 

Cheng-Yin>  I am afraid the WG may not be producing useful work. 

Suppose the WG  produced something which only handled  99.9% of the existing
base.  Would this be "not useful"?

---

From: "Steven.Wright" <[email-masked]>
Date: Fri, 16 May 2003 09:48:10 -0400

Assuming the WG is to be split in order to  provide greater focus and
progress the work,...

I have some doubts that the current proposals to partition along the lines
of Layer2 vs Layer 3 PPVPNs will achieve (my) desired results in terms of
providing effective solutions for any of my network service problems.
Instead, I expect this will result in elegant solutions to the wrong
problems which will ultimately prove difficult for folks like me to utilize.

I think it would behoove the group to consider splitting between (i)
INTRA-AS PPVPN and (ii)INTER-AS PPVPNs . I expect this partition would
reflect real differences in
1) the scaling properties of the underlying solutions
2) the types of SPs interested in these protocols
3) the service problems that these SPs are interested in having solved
4) the protocol environments in which solutions must be found.

Such a split would also allow both groups to focus on developing and
leveraging commonality between the L2 & L3 VPN solutions where possible.

regards
Steven Wright

---

From: Yakov Rekhter <[email-masked]>
Date: Tue, 20 May 2003 08:23:38 -0700

Alex,

> exactly your proposed text would mean.

This should be in the charter for exactly the same reason(s) it is
in the current PPVPN charter. It means exactly the same as it
means in the current PPVPN charter.

Yakov.

---

From: Alex Zinin <[email-masked]>
Date: Fri, 23 May 2003 16:24:31 -0700

Yakov,

> means in the current PPVPN charter.

Many people on this list (including me) were not intimately involved
in writing of the PPVPN WG charter. Therefore, I believe you should
explain your reasoning (i.e. why you think the text is useful, how,
and what it really means) before we can consider putting this phrase
in the proposed charter.

Alex

---

From: Alex Zinin <[email-masked]>
Date: Fri, 23 May 2003 16:23:12 -0700

Reading the discussion between Matt, Eric, et al, it seems that
we have two main questions at hand:

 1. Should the charter define the level of transparency of
    the L2 VPN mechanisms to the higher-layer protocols, and
    if so, what should the required level be?

 2. Should the charter say that the WG will work with IEEE 802.1
    to ensure proper interworking.

My reading of the discussion on the first item is that we don't have a
strong case for spelling out that a perfect emulation is required.
If anyone disagrees, please speak up.

I didn't see a discussion on the second issue, but it seems like a
reasonable proposal to me.

Alex

---

From: "Mark Seery" <[email-masked]>
Date: Fri, 23 May 2003 20:04:40 -0700

Alex,

Perhaps not emulation, but I think a definition of "LAN" might be useful.
i.e. a broadcast/multicast segment, the interconnection of emulated bridges,
a single virtual bridge, etc. Or if that granularity of description is not
desired by the group, then a statement to that effect.

As to perfect, or imperfect I have not strong opinion, as long as people are
comfortable that standars compliant Ethernet devices are able to attach to
the service and use it.

Mark

-----Original Message-----
From: Alex Zinin [mailto:[email-masked]]
Sent: Friday, May 23, 2003 4:23 PM
To: [email-masked]
Subject: Re: Draft charter for L2VPN: Perfect LAN emulation

Alex

---

From: Stewart Bryant <[email-masked]>
Date: Sat, 24 May 2003 08:41:08 +0100

If the plan is still to run the L2VPN over PWE3, then you should
note the PWE3 charter does not curently require us to provide
perfect emulation:

   "PWE3 will not strive for pseudo wires to perfectly emulate the
   characteristics of the native service.  For each type of pseudo
   wire, an applicability statement will describe the degree of
   similarity of a pseudo wire to the native service it emulates."

However Mark's criteria for L2VPN seems the right benchmark:

"as long as people are comfortable that standards compliant
"Ethernet devices are able to attach to the service and use it."

Stewart

---

From: Muneyoshi Suzuki <[email-masked]>
Date: Mon, 26 May 2003 17:42:11 +0900 (JST)

> reasonable proposal to me.

I support this.

Thanks,

Muneyoshi Suzuki

---

From: "mark seery" <[email-masked]>
Date: Mon, 26 May 2003 07:02:00 -0700

if we do, then some discussion about whether we specify service or network
interworking, or whether it is left open, would be useful. personally would
like to see a service interworking capability as I think a) it is more
scalable b) is less likely to create conflict between IEEE and IETF and c)
better leverages the underlying PSN technology.

mark

-----Original Message-----
From: Muneyoshi Suzuki [mailto:[email-masked]]
Sent: Monday, May 26, 2003 1:42 AM
Cc: [email-masked]; [email-masked]
Subject: Re: Draft charter for L2VPN: Perfect LAN emulation

I support this.

Thanks,

Muneyoshi Suzuki

---

From: "Mark Seery" <[email-masked]>
Date: Mon, 26 May 2003 11:24:18 -0700

referring to multipoint only, not P2P.

and guess I shouldn;t just throw the scalable flag out there. concerned
about the complexities of running an Ethernet control plane over a PSN
control plane: do we end up having to solve Ethernet issues, what will be
the interaction between the two layers, ethernet is not just a simple data
link layer - it is a protocol that spans multiple data links - it is in a
sense approaching a network layer protocol......

Mark

-----Original Message-----
From: mark seery [mailto:[email-masked]]
Sent: Monday, May 26, 2003 7:02 AM
To: Muneyoshi Suzuki
Cc: [email-masked]
Subject: RE: Draft charter for L2VPN: Perfect LAN emulation

mark

---

From: "Cheng-Yin Lee" <[email-masked]>
Date: Mon, 26 May 2003 18:24:19 -0400

Alex,

>     if so, what should the required level be?
I think a definition of the service being specified in the WG would be
needed. 

Wrt level of transparency, I think the minimal requirement is any
non-transparent characteristics must not affect the operation of these
higher layer protocols.

For VPLS, a definition of the service being specified in the WG would be
helpful. 
Here's one suggestion :
An emulated LAN service allows the inter-connection of (geographically)
dispersed devices, not connected over a LAN segment, as if they were
attached to a single LAN.
Hence standard compliant devices (e.g. bridges, routers, hosts) would be
able to work as if they are connected to a LAN when connected to the
emulated LAN service.

An emulated LAN service operates below the MAC Service Boundary, and is
transparent to protocols operating above this boundary.
The emulation may be imperfect in terms of QoS (limitation should be
documented in solution specifications), compared to operation over a
LAN, as long as the differences/degradation in the emulated service does
not prevent standard compliant devices from functioning. However, the
emulated LAN service must not introduce artifacts which break the
operation of standard compliant devices.

> If anyone disagrees, please speak up.
I think a definition of the desired LAN emulation service is useful. I
am not clear if there is agreement on this or what is "perfect
emulation".

> reasonable proposal to me.
Yes.

Thanks
Cheng-Yin

---

From: Yakov Rekhter <[email-masked]>
Date: Tue, 27 May 2003 07:23:16 -0700

Alex,

> and what it really means) before we can consider putting this phrase

I would suggest that the folks who wrote the PPVPN WG charter (the IESG 
ADs + the WG chairs) should do this. 

Yakov.