The MPLS WG Archive

[Shahram Davari <Shahram_Davari@pmc-sierra.com>]

Hi,
 
1) Please check RFC 2481 for the definition and usage of ECN. 
2) As far as I know there is currently no proposal to use ECN bits in an
Edge-to-Edge level. The intention of Sally Floyd's draft was that ECN to be
used with TCP (end-to-end). 
 
Regards,
Shahram

-----Original Message-----
From: CATANZARITI Sergio FTR&D/TI
[mailto:sergio.catanzariti@rd.francetelecom.com]
Sent: Wednesday, May 31, 2000 3:13 PM
To: 'Shahram Davari'
Cc: mpls@UU.NET; 'Andrzej Czerczak'; rraszuk@cisco.com
Subject: RE: Re: MPLS - ATM interworking?



Shahram, 

	the draft-ietf-mpls-ecn-00.txt does not say anything about ECN usage
and applications, but only about ECN support and definition in an MPLS
network, the things are quite different. So, I have the same question: where
I can find Ramakrishnan et al., "A Proposal to Incorporate ECN in MPLS",
draft-ietf-mpls-ecn-00.txt?

	Also, I do believe that the ECN in an MPLS network works on resource
types (LSPs) quite different than native IP flows. So, the source address is
not that useful here, albeit in an ECN schema in pure IP networks.

	ECN in an MPLS network is supposed to signal congestion in an
edge-to-edge fashion (different from end-to-end) where the LERs could
cooperate on that.

	Absolutely, I want to associate LSPs with congestion dynamics to
eventually slow them down. How can I do that? That's the question.

Sergio 

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	-----Original Message----- 
From:   Shahram Davari [SMTP:Shahram_Davari@pmc-sierra.com] 
Sent:   Wednesday, May 31, 2000 11:34 AM 
To:     'Andrzej Czerczak'; rraszuk@cisco.com 
Cc:     mpls@UU.NET 
Subject:        RE: Re: MPLS - ATM interworking? 

	Andrzej, 

	1)ECN usage is defined in draft-ietf-mpls-ecn-00.txt, which is
attached to 
this email. 

	2)Congestion Notification is and end-to-end signal which is meant to
be used 
by TCP. You don't need to know the ingress LSR or even the LSP from which 
the congested packet is received. The receiver may send the congestion 
notification to the sender using source IP address, either through another 
LSP or even through normal IP hop-by-hop routing. 

	Regards, 
-Shahram 




	>-----Original Message----- 
>From: Andrzej Czerczak [ mailto:Andrzej_Czerczak/HeadQ@netia.pl
<mailto:Andrzej_Czerczak/HeadQ@netia.pl> ] 
>Sent: Wednesday, May 31, 2000 1:46 PM 
>To: rraszuk@cisco.com 
>Cc: mpls@UU.NET 
>Subject: Re:Re: MPLS - ATM interworking? 
> 
> 
> 
>Robert, 
>First of all thanks for your comments. 
> 
>>Have you read draft MPLS Support of Differentiated Services 
>>draft-ietf-mpls-diff-ext-04.txt where we are proposing to use the ECN 
>>(explicit congestion notification) on a per LSP basis using 
>the EXP bits 
>>in the shim header ? Currently this is the most attractive 
>option, but I 
>> am not aware of any implementation support this today. 
> 
> 
> 
>a) Document draft-ietf-mpls-diff-ext-04.txt does not not 
>define the usage 
>of ECN. 
> 
>b) Taking into account label merging capabilites of LSRs, how 
>can determine 
>to which ingress LSP to to send Congestion Notification? 
> 
>c) Where can I find: 
> 
>Ramakrishnan et al., "A Proposal to Incorporate ECN in 
>   MPLS", draft-ietf-mpls-ecn-00.txt? 

	> 
> 
> 
>What I'd like to say is, that at least during first phases of 
>implementations (before entire infrastructure will become IP) 
>interworking 
>of MPLS core and ATM edge will be important, but I could not find a 
>proposal of how to do interworking between them. 
> 
> 
> 
>Andrzej 
> 
> 
> 
> 
> 
> 
 << File: draft-mpls-ecn-00.txt >>