Hi Acee,

  Defining a new MRT sub TLV to be carried in the OSPFv2 Extended link TLV as 
defined in
https://datatracker.ietf.org/doc/draft-ietf-ospf-segment-routing-extensions/

 "Router-Link TLVs"as defined in 
https://datatracker.ietf.org/doc/draft-ietf-ospf-ospfv3-lsa-extend

looks to be a good option. We will work on the draft to update.

Rgds
Shraddha

-----Original Message-----
From: OSPF [mailto:[email protected]] On Behalf Of Acee Lindem
Sent: Tuesday, July 15, 2014 1:18 AM
To: Chris Bowers
Cc: OSPF List; Alia Atlas
Subject: Re: [OSPF] draft-atlas-ospf-mrt-02

Hi Chris, Shraddha,  

On Jul 14, 2014, at 3:36 PM, Chris Bowers <[email protected]> wrote:

> (The response to this question ended up off of the list, so I'm posting it to 
> continue the discussion on the list.) 
> 
> Russ,
> 
> I see your point in link information being carried in Node related LSA.
> 
> The link information is carried in Router LSA and it's not extendible to 
> carry any other information.
> Since RI-LSA is modeled as an extension to Router LSA, my idea was to tag the 
> additional link information With new TLV in RI-LSA.
> 
> Another approach could have been to define a new LSA type and originate a new 
> LSA for each link which is in-eligible to participate in MRT. A separate LSA 
> for each link to advertise ineligibility looks suboptimal considering the 
> amount of state machine/data structure that needs to be maintained for a 
> separate LSA.
> 
>>> It seems like it might be better to move this bit of information into the 
>>> TLV where the actual link state is advertised in some way.
> 
> Link related information is advertised in OSPF-TE opaque LSAs as well. MRT 
> could run on non-TE enabled networks as well, so it may not be appropriate to 
> use TE LSAs.
> 
> Let me know if you think we could stuff-in in existing LSAs or we should go 
> with new LSA altogether.

Do NOT use the OSPF RI LSA for link information. Rather than define a new LSA, 
use the OSPFv2 Extended-Link opaque LSA defined in 
https://datatracker.ietf.org/doc/draft-ietf-ospf-segment-routing-extensions/

Thanks,
Acee



> 
> Rgds,
> Shraddha
> 
> -----Original Message-----
> From: OSPF [mailto:[email protected]] On Behalf Of Russ White
> Sent: Sunday, July 06, 2014 7:41 AM
> To: 'OSPF List'
> Cc: Alia Atlas
> Subject: [OSPF] draft-atlas-ospf-mrt-02
> 
> 
> Just one question/comment on this draft -- In section 6.1, MRT-Ineligible 
> Links TLV for OSPFv2, the draft says there should be a new TLV in the router 
> capabilities LSA that advertises links not to be included in the MRT 
> calculation (excluded links). I'm not certain why an option isn't used in the 
> LSA header for this, instead. Two things that seem strange to me:
> 
> - The exclusion of a link is a link property, not a router property, so I'm 
> not certain why this would be advertised as a property of the OSPF router.
> This seems to muddy the line between router and properties and link 
> properties in a way that sets the stage for make the router capabilities just 
> another area into which to stuff various bits of information we can't find a 
> home for elsewhere.
> 
> - If you modify a specific link state, then you must advertise two TLVs, or 
> rather two LSAs, rather than one. Thus these two pieces of information must 
> be connected in a local database, but advertised separately, with all the 
> coordination/etc. that implies.
> 
> It seems like it might be better to move this bit of information into the TLV 
> where the actual link state is advertised in some way.
> 
> :-)
> 
> Russ
> 
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