Re: [Lsr] I-D Action: draft-ietf-ospf-mpls-elc-15.txt

Peter,

-----Original Message-----
From: Peter Psenak [mailto:ppsenak@cisco.com] 
Sent: Tuesday, June 2, 2020 4:10 PM
To: Tianran Zhou <zhoutianran@huawei.com>; lsr@ietf.org
Subject: Re: [Lsr] I-D Action: draft-ietf-ospf-mpls-elc-15.txt

Tianran,

On 02/06/2020 08:14, Tianran Zhou wrote:
> Hi Peter,
> 
> I do not understand how RFC8667 relates to ELC signaling.

RFC 8667 - IS-IS Extensions for Segment Routing

> RFC 8667 "have been defined to signal labels", but "This draft defines a mechanism to signal the ELC using IS-IS."

yes, and as labels are now signaled by IGPs, we provide a method to signal ELC/ERLD by IGPs as well.

ZTR> RFC8667 signals different SID. But draft-ietf-ospf-mpls-elc is about entropy label. Or do you mean entropy label is also signaled by IGP?

> 
> On the other hand, RFC 8667 is the extension for segment routing.
> Is this draft only for segment routing, or be generic?

the requirement document is RFC8662, which is SR specific.

ZTR> "This draft" I mean draft-ietf-ospf-mpls-elc. So is draft-ietf-ospf-mpls-elc SR specific?

Thanks,
Tianran

> 
> Another thing I am not clear is the difference between "multi-area" and "multi-domain" here after:
>     "Even though ELC is a property of the node, in some cases it is
>     advantageous to associate and advertise the ELC with a prefix.  In a
>     multi-area network, routers may not know the identity of the prefix
>     originator in a remote area, or may not know the capabilities of such
>     originator.  Similarly, in a multi-domain network, the identity of
>     the prefix originator and its capabilities may not be known to the
>     ingress LSR."

multi area is single IGP with multiple areas. Mutli domain is multiple IGPs.

thanks,
Peter

> 
> Tianran
> 
> -----Original Message-----
> From: Peter Psenak [mailto:ppsenak@cisco.com]
> Sent: Monday, June 1, 2020 6:56 PM
> To: Tianran Zhou <zhoutianran@huawei.com>; lsr@ietf.org
> Subject: Re: [Lsr] I-D Action: draft-ietf-ospf-mpls-elc-15.txt
> 
> Tianran,
> 
> On 01/06/2020 12:49, Tianran Zhou wrote:
>> Hi Authors,
>>
>> I see the following words in the introduction.
>> "   Recently, mechanisms have been defined to signal labels via link-
>>      state Interior Gateway Protocols (IGP) such as IS-IS [RFC8667].  "
>>
>> It's not clear to me what the " mechanisms " are. Could you please add some reference or text on this?
> 
> the reference is there - RFC8667.
> 
> 
> thanks,
> Peter
> 
>>
>> Thanks,
>> Tianran
>>
>> -----Original Message-----
>> From: Lsr [mailto:lsr-bounces@ietf.org] On Behalf Of 
>> internet-drafts@ietf.org
>> Sent: Monday, June 1, 2020 4:42 PM
>> To: i-d-announce@ietf.org
>> Cc: lsr@ietf.org
>> Subject: [Lsr] I-D Action: draft-ietf-ospf-mpls-elc-15.txt
>>
>>
>> A New Internet-Draft is available from the on-line Internet-Drafts directories.
>> This draft is a work item of the Link State Routing WG of the IETF.
>>
>>           Title           : Signaling Entropy Label Capability and Entropy Readable Label Depth Using OSPF
>>           Authors         : Xiaohu Xu
>>                             Sriganesh Kini
>>                             Peter Psenak
>>                             Clarence Filsfils
>>                             Stephane Litkowski
>>                             Matthew Bocci
>> 	Filename        : draft-ietf-ospf-mpls-elc-15.txt
>> 	Pages           : 9
>> 	Date            : 2020-06-01
>>
>> Abstract:
>>      Multiprotocol Label Switching (MPLS) has defined a mechanism to load-
>>      balance traffic flows using Entropy Labels (EL).  An ingress Label
>>      Switching Router (LSR) cannot insert ELs for packets going into a
>>      given Label Switched Path (LSP) unless an egress LSR has indicated
>>      via signaling that it has the capability to process ELs, referred to
>>      as the Entropy Label Capability (ELC), on that LSP.  In addition, it
>>      would be useful for ingress LSRs to know each LSR's capability for
>>      reading the maximum label stack depth and performing EL-based load-
>>      balancing, referred to as Entropy Readable Label Depth (ERLD).  This
>>      document defines a mechanism to signal these two capabilities using
>>      OSPFv2 and OSPFv3 and BGP-LS.
>>
>>
>> The IETF datatracker status page for this draft is:
>> https://datatracker.ietf.org/doc/draft-ietf-ospf-mpls-elc/
>>
>> There are also htmlized versions available at:
>> https://tools.ietf.org/html/draft-ietf-ospf-mpls-elc-15
>> https://datatracker.ietf.org/doc/html/draft-ietf-ospf-mpls-elc-15
>>
>> A diff from the previous version is available at:
>> https://www.ietf.org/rfcdiff?url2=draft-ietf-ospf-mpls-elc-15
>>
>>
>> Please note that it may take a couple of minutes from the time of submission until the htmlized version and diff are available at tools.ietf.org.
>>
>> Internet-Drafts are also available by anonymous FTP at:
>> ftp://ftp.ietf.org/internet-drafts/
>>
>>
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> 
> 
> 