Re: [mpls-tp] [PWE3] Proposal of using GAL for PW

["HUANG Feng F" <[e-mail]>]

Dear Sasha,
   In MPLS-TP transport network environment, because it is strict connected oriented, ECMP is not supported.
B.R.
Feng
 


________________________________

From: [e-mail] [mailto:[e-mail]] On Behalf Of Alexander Vainshtein
Sent: 2010年7月5日 20:42
To: BUSI ITALO
Cc: [e-mail]; [e-mail]; [e-mail]; [e-mail]
Subject: Re: [PWE3] [mpls-tp] Proposal of using GAL for PW



Italo,

Lots of thanks for a prompt response. However, IMHO it is not correct.

 

E.g., BFD for MPLS LSP (as defined RFC 5884) and BFD in VCCV (as defined in RFC 5885) will provide correct connectivity failure indications regardless of ECMP based on MPLS stack hashing because the same label stack will be used by user traffic and OAM packets. 

 

Do you think I’ve missed something?

 

Regards,

     Sasha

 

From: BUSI, ITALO (ITALO) [mailto:[e-mail]] 
Sent: Monday, July 05, 2010 3:29 PM
To: Alexander Vainshtein; [e-mail]; Shahram Davari
Cc: [e-mail]; [e-mail]; [e-mail]
Subject: RE: [PWE3] [mpls-tp] Proposal of using GAL for PW

 

Sasha,

 

what you say is correct but it is applicable to any environment where you use OAM together with ECMP. I do not see anything specific with GAL and PW.

 

Italo

	 

	
________________________________


	From: Alexander Vainshtein [mailto:[e-mail]] 
	Sent: lunedì 5 luglio 2010 10.39
	To: BUSI, ITALO (ITALO); [e-mail]; Shahram Davari
	Cc: [e-mail]; [e-mail]; [e-mail]
	Subject: RE: [PWE3] [mpls-tp] Proposal of using GAL for PW

	Hi all,

	IMHO and FWIW, while RFC 5586  (5886 looks like a typo to me) does not place any restrictions on using GAL in non-TP environments, its usefulness in these environments (where various forms of multipath, including usage of entropy labels,  cannot be precluded) for OAM purposes is somewhat problematic: 

	Adding GAL to the label stack changes this for the multipath mechanisms based on stack hashing, and fate-sharing of OAM and user traffic packets is not guaranteed any more.

	 

	My 2c,

	     Sasha

	 

	From: [e-mail] [mailto:[e-mail]] On Behalf Of BUSI, ITALO (ITALO)
	Sent: Monday, July 05, 2010 11:17 AM
	To: [e-mail]; Shahram Davari
	Cc: [e-mail]; [e-mail]; [e-mail]
	Subject: Re: [PWE3] [mpls-tp] Proposal of using GAL for PW

	 

	I agree with Stewart.

	 

	The GAL MUST be at the BoS in MPLS-TP where ECMP is not applicable and entroy labels MUST NOT be used.

	 

	In other MPLS environments (e.g., where entropy labels are used), RFC 5886 does not place any restriction on the position of the GAL within the label stack.

	 

	Italo

		 

________________________________

		From: [e-mail] [mailto:[e-mail]] On Behalf Of Stewart Bryant
		Sent: venerdì 2 luglio 2010 11.24
		To: Shahram Davari
		Cc: Andy Malis; [e-mail]; [e-mail]; [e-mail]; HUANG, Feng F (Feng)
		Subject: Re: [mpls-tp] [PWE3] Proposal of using GAL for PW

		On 01/07/2010 19:35, Shahram Davari wrote: 

		!mmm so if one used entropy then they can’t have OAM?

		-SD

		
		Not so. The GAL goes above the entropy label (S=0), so gets parsed first. This works for both PHP and not PHP, and both LSP and PW.
		
		- Stewart