RE: draft-bryant-mcpherson-pwe3-cw-00.txt WG request

["Florin Balus" <[e-mail]>]

Peter,
See in-line...
 
Stewart,
There might be another motivator for a mandatory CW/consolidation under PTI:
assuming we have a PW type that does not mandate a CW (ATM N to one cell
mode) couldn't we get payloads that are mistaken also for 0001/VCCV packets
- e.g. VPI 64 in an ATM cell could be interpreted by the receiving PE as
0001? (thanks Jeff for bringing this up)
 
Regards,
Florin

-----Original Message-----
From: Busschbach, Peter B (Peter) [mailto:[e-mail]] 
Sent: Wednesday, August 11, 2004 2:41 PM
To: Balus, Florin [CAR:6955:EXCH]; Stewart Bryant
Cc: [e-mail]
Subject: RE: [PWE3] draft-bryant-mcpherson-pwe3-cw-00.txt WG request


Florus,
 
Draft-allan-mpls-pid-00.txt  is not accessible anymore. I don't recall what
rationale it gave for the need for a PTI.

FB: Dave addressed the need for an MPLS PID one year ago from an overall
MPLS perspective: e.g. issues arisen from loadsharing on TE link bundles or
ECMP in LDP network,  OAM extensibility, Multiprotocol over MPLS...
 
Draft-bryant-mcpherson-pwe3-cw-00.txt mentions ECMP as the sole reason for
an additional control word. However, introducing PTI to solve the issues
related to ECMP seems overkill. It would be good if we can clearly state why
we need a PTI.
FB I agree with you that the justification in section 4 for PTI versus CW +
VCCV could be improved. On the other hand we need the extensibility provided
by a PTI/PID:  VCCV is just an instantiation of a PTI if you think about it,
just the formats need to be aligned. 
Whether or not is a good idea to move the PW user data to 0001 format is to
be debated. We need to make sure though the 2 formats could coexist in a
network in the mean time.
 
Peter 

-----Original Message-----
From: Florin Balus [mailto:[e-mail]]
Sent: Wednesday, August 11, 2004 2:17 PM
To: Stewart Bryant
Cc: [e-mail]
Subject: RE: [PWE3] draft-bryant-mcpherson-pwe3-cw-00.txt WG request




Stewart, 

We did promote the idea of a PID/PTI - see Dave Allan's
draft-allan-mpls-pid-00.txt on the subject. Also I think the explanation of
ECMP issue (disambiguate from IP/MPLS packets etc) and the overall proposed
solution are valid.

I just wanted to clarify some technicalities to make sure we clearly
identify where we are headed to - i.e. what changes are required in other
PWE3 drafts.

Assuming we have in the same network PEs that support both formats: 
 - the CW [(0000 CW stuff)(data) & the current VCCV format (0001 PA
PPP_DLL)(OAM payload))] 
 - and the newly defined PTI (0001 PTI)(data/VCCV payload/?whatever?). 
In the same time let's assume other PEs will accept just the PTI - being
part of those implementations that do not support 0000. How are we going to
ensure the 2 sets of PEs will be able to negotiate in the control plane the
right format?


Currently we do have in each of the 2 L2 FECs (PWID and Generalized ID) just
one bit to determine whether or not the CW should be used - see
draft-ietf-pwe3-control-protocol-07.txt section 5.1 and 5.2.2. 0001
implicitly meant up to now VCCV format. How do we differentiate the other 2
possibilities (PTI yes/no)?

Also just to make sure I understood correctly: there are some PW types for
which the CW is REQUIRED (e.g. ATM N to 1 Cell Mode and AAL5 SDU Frame Mode
- see draft-ietf-pwe3-atm-encap-05.txt section 4.3.2). For a PE that will
implement the PTI format are we saying the PW frames (after the 2 labels)
will look like this: (0001  PTI)(0000 CW stuff)(data)?

Is VCCV/OAM going to be differentiated in the same way, just re-using what
is already defined: i.e. (0001  PTI)(0001 PA PPP_DLL)(OAM payload)? If not I
assume we will need to clarify the PTI code points that are going to be used
for VCCV/OAM payload? 

Thanks for clarifying the above points. 
Regards, 
Florin 


-----Original Message----- 
From: [e-mail] [mailto:[e-mail]
<mailto:[e-mail]> ] On Behalf Of Stewart Bryant 
Sent: Monday, August 09, 2004 7:54 AM 
To: [e-mail] 
Subject: [PWE3] draft-bryant-mcpherson-pwe3-cw-00.txt WG request 


The authors request that 

http://www.ietf.org/internet-drafts/draft-bryant-mcpherson-pwe3-cw-00.txt
<http://www.ietf.org/internet-drafts/draft-bryant-mcpherson-pwe3-cw-00.txt>


be adopted as a WG item with its title changed to 

PWE3 MPLS Control Word 

- Stewart 







_______________________________________________ 
pwe3 mailing list 
[e-mail] 
https://www1.ietf.org/mailman/listinfo/pwe3
<https://www1.ietf.org/mailman/listinfo/pwe3>  

_______________________________________________
pwe3 mailing list
[e-mail]
https://www1.ietf.org/mailman/listinfo/pwe3