Re: [Isis-wg] comment on draft-ietf-isis-segment-routing-extensions-02

my point is that description of use cases should be on a 
separate document in order to avoid replication of text 
between isis and ospf drafts.

Protocol extensions drafts should be focused on bits/bytes 
to be carried by the protocol. 

I think there's agreement on this.

s.

On Aug 1, 2014, at 8:57 PM, Chris Bowers wrote:

> I disagree.  The proposed text contains four Binding TLV usage examples which are not qualitatively different from the two usage examples already included in section 2.4.3 of draft-ietf-isis-segment-routing-extensions-02.  Additional usage examples are needed to clarify how the TLVs and sub-TLVs defined in this document should be used, without ambiguity.
> 
> As an example of the lack of clarity in the current text,  draft-ietf-isis-segment-routing-extensions-02 contains two different sub-TLVs for specifying SID/Label values in the Binding TLV. The two options are the SID/Label Sub-TLV (section 2.3) and the Prefix-SID Sub-TLV (section 2.1).  The current text does not clearly explain under what circumstances the two different sub-TLVs should be used in the Binding TLV.   The proposed text makes the usage clear by means of examples.   
> 
> Chris
> 
> -----Original Message-----
> From: Stefano Previdi (sprevidi) [mailto:sprevidi@cisco.com] 
> Sent: Friday, August 01, 2014 1:54 AM
> To: Uma Chunduri
> Cc: Chris Bowers; isis-wg@ietf.org; spring@ietf.org
> Subject: Re: [Isis-wg] comment on draft-ietf-isis-segment-routing-extensions-02
> 
> Uma,
> 
> I agree.
> 
> I think we also explicitly stated this during our meeting in Toronto (from the minutes):
> 
>   --------------------------------------------------------------------
>   Uma: Needed to reference use cases in Hannes' draft.
>   Hannes: Perhaps what we could do is add some practical examples for
>           RSVP, BGP, and LDP LSPs binding. Not formal use cases.
>   Stefano: Would rather not go into applications in this ISIS draft.
>   Peter Psenak: Should go into a separate document that could be
>           referenced from both ISIS and OSPF.
>   Alia Atlas: There is a SPRING WG for such a document.
>   -------------------------------------------------------------------
> 
> Now, note that:
>   draft-filsfils-spring-segment-routing
>   draft-filsfils-spring-segment-routing-ldp-interop
> 
> describe the use case of the SR Mapping Server that is implemented using the Binding TLV.
> 
> As you suggested, Hannes drafts can be combined so to produce a use-case document (in spring) for the Binding TLV RSVP-based use-cases.
> 
> 
> s.
> 
> 
> On Jul 31, 2014, at 11:55 PM, Uma Chunduri wrote:
> 
>> [CC'ed Spring WG]
>> 
>> I agree with what Chris said below in principle. But all this should not be obviously part of ISIS/IGP extensions WG documents..
>> 
>> Use  cases for binding TLVs are explained in great details in 2 key 
>> documents (had to shuffle through to get here) -
>> 
>> 1.       http://tools.ietf.org/html/draft-gredler-rtgwg-igp-label-advertisement-05
>> 2.       http://tools.ietf.org/html/draft-gredler-spring-mpls-06
>> 
>> IMO, both are very useful documents.
>> It would be good  to combine both of these and publish as a "spring " document and eventually it should progress there.
>> AFAICT, Both ISIS and OSPF should refer the same eventually to get more clarity and use of binding TLVs described currently.
>> 
>> --
>> Uma C.
>> 
>> From: Isis-wg [mailto:isis-wg-bounces@ietf.org] On Behalf Of Chris 
>> Bowers
>> Sent: Thursday, July 31, 2014 2:42 PM
>> To: isis-wg@ietf.org
>> Subject: [Isis-wg] comment on 
>> draft-ietf-isis-segment-routing-extensions-02
>> 
>> All,
>> 
>> The current text of draft-ietf-isis-segment-routing-extensions-02 does not clearly explain the usage of the Binding TLV for advertising LSPs created using other protocols.  I would like to propose the following text to be included as section 2.5 .
>> 
>> Thanks,
>> Chris
>> 
>> ----------------
>> 
>> 2.5 Binding TLV usage examples
>> 
>> This section gives examples of using the Binding TLV to advertise SID/label bindings associated with RSVP-TE, LDP, and BGP labeled-unicast LSPs.  It also includes an example of advertising a context-id for egress node protection.  All of the examples assume that the Binding TLV weight=1 and metric=100. 
>> 
>> 2.5.1 Advertising an RSVP-TE LSP using the Binding TLV
>> 
>> Assume that R1 has signaled an RSVP-TE LSP to egress router (R4) with router-id=10.4.4.4, with ER0 = (192.1.2.2 [strict], 192.2.3.2 [strict], 192.3.4.2 [strict]). R1 can advertise a locally significant label binding for this LSP (with label value=1099)  using the following values and sub-TLVs in the Binding TLV. 
>> 
>> Binding-TLV: F-bit=0, M-bit=0, weight=1, range=1, prefix length=32, 
>> FEC prefix=10.4.4.4 SID/Label Sub-TLV: label=1099 ERO Metric sub-TLV: 
>> metric=100
>> IPv4 ERO sub-TLV: L-bit=0, IPv4 address=192.1.2.2
>> IPv4 ERO sub-TLV: L-bit=0, IPv4 address=192.2.3.2
>> IPv4 ERO sub-TLV: L-bit=0, IPv4 address=192.3.4.2
>> 
>> 2.5.2 Advertising an LDP LSP using the Binding TLV
>> 
>> Assume that R5 has learned a FEC-label binding via LDP for FEC=10.8.8.8/32.  R5 can advertise a locally significant label binding for this LSP (with label value=5099) using the following values and sub-TLVs in the Binding TLV. 
>> 
>> Binding TLV: F-bit=0, M-bit=0, weight=1, range=1, prefix length=32, 
>> FEC prefix=10.8.8.8 SID/Label Sub-TLV: label=5099 ERO Metric sub-TLV: 
>> metric=100
>> IPv4 ERO sub-TLV: L-bit=1, IPv4 address=10.8.8.8
>> 
>> 2.5.3 Advertising a BGP labeled-unicast LSP using the Binding TLV
>> 
>> Assume that R9 has used BGP labeled-unicast to learn a label binding for prefix 10.15.15.15/32 with BGP next-hop=10.12.12.12.   R9 can advertise a locally significant label binding for this LSP (with label value=7099)  using the following values and sub-TLVs in the Binding TLV. 
>> 
>> Binding-TLV: F-bit=0, M-bit=0, weight=1, range=1, prefix length=32, 
>> FEC prefix=10.15.15.15 SID/Label Sub-TLV: label=7099 ERO Metric 
>> sub-TLV: metric=100
>> IPv4 ERO sub-TLV: L-bit=1, IPv4 address=10.12.12.12
>> 
>> 2.5.4 Advertising a context-id for egress node protection using the 
>> Binding TLV
>> 
>> Assume that R22 is configured in the protector role to provide egress node protection for R21 using context-id=10.0.0.21.  R22 can advertise the label associated with this context-id (with label value=8099) using the following values and sub-TLVs in the Binding TLV.
>> 
>> Binding TLV: F-bit=0, M-bit=1, weight=1, range=1, prefix length=32, 
>> FEC prefix=10.0.0.21 SID/Label Sub-TLV: label=8099
>> 
>> ----------------
>> 
>> 
>> 
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> 