Subject: Re: issue in draft-martini-ethernet-encap-mpls-00.txt

From: Giles Heron <[email-masked]>
Date: 18 Apr 2002 15:35:27 +0000

On Thu, 2002-04-18 at 14:13, Eric Rosen wrote:
> Vach> Suppose customer A has two sites  connected via an L2 ethernet PW.  At
> Vach> one end, the customer comes  in through an aggregation device, and has
> Vach> to  be distinguished  by  VLAN.  At  the  other end,  the customer  is
> Vach> assigned  a physical  port.  Now,  should the  *signaling* have  to be
> Vach> aware  of  this  difference?   I  would say,  no.   With  the  martini
> Vach> signaling the way it  is, we have to either define it  as VLAN at both
> Vach> ends or  Ethernet at  both ends, and  signal the PW  accordingly.  And
> Vach> since the VLAN tag  is necessary on the one end, it  is imposed at the
> Vach> other end too.
> 
> I think you're saying:
> 
> - the PW  should be able to carry whatever frame  the customer has produced,
>   whether it has a VLAN tag or not;
> 
> - in the case  where a VLAN tag is used as  a customer service delimiter, it
>   is entirely a local matter to remove the VLAN tag before sending the frame
>   on the PW, and  to add it after received the frame on  the PW (so that the
>   signaling should not know anything about it). 
> 
> This makes sense to me. 
> 
> I think  the implication  then is that  we only  need one ethernet  PW type,
> rather than two. 

agreed.  I think it was probably a mistake to specify two types in
draft-martini.

> I  note that  some of  the  VPLS proposals  in PPVPN  specify additional  PW
> types for use in VPLS.  I suspect we don't need those either. 

possibly.  I think the reason for the additional type in VPLS was so
that the PEs know to implement split-horizon on these VCs.  If a VC is
signalled as Ethernet or Ethernet VLAN then it is a "spoke" VC and
split-horizon should not be implemented.

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

---

From: "Vach Kompella" <[email-masked]>
Date: Thu, 18 Apr 2002 09:15:06 -0700

See below.

-Vach

> From: Eric Rosen [mailto:[email-masked]]
> Sent: Thursday, April 18, 2002 7:13 AM
> To: Vach Kompella
> Cc: Claude Kawa; [email-masked]
> Subject: Re: [PWE3] issue in draft-martini-ethernet-encap-mpls-00.txt
>
>

Great!  Maybe we can change draft-martini-ethernet to say that.

> I think  the implication  then is that  we only  need one ethernet  PW type,

Ditto.

> types for use in VPLS.  I suspect we don't need those either.

Actually, the -01 version of the VPLS draft has dropped the second type,
reducing the behavior to just one VC type along the lines of what I suggested
above.  The variations in learning are specified in a separate bit (qualified
vs. unqualified) as they are properties of the L2VPN and not the PW.  The spoke
vs. hub of a pipe is more of a "this is a pt2pt pipe vs. a simulated
pt2multipoint PW" attribute and currently is identified by the VC type.  We
would use a regular draft-martini VC type 4 or 5 for the spoke and a VPLS VC
type for the hub side.

-Vach