Re: [Isis-wg] New Version Notification for draft-xu-isis-routable-ip-address-00.txt

[Uma Chunduri <[e-mail]>]

Les,

In-line [Uma]:

--
Uma C.


-----Original Message-----
From: Isis-wg [mailto:[e-mail]] On Behalf Of Les Ginsberg (ginsberg)
Sent: Wednesday, May 28, 2014 9:58 PM
To: Xuxiaohu; [e-mail]
Subject: Re: [Isis-wg] New Version Notification for draft-xu-isis-routable-ip-address-00.txt

Xiaohu/Uma -

Regardless of the name, I see no reason for this draft. :-)
RFC 5305 and RFC 6119 define the IPv4 and IPv6 Router ID TLVs. Those RFCs specifically state that the router id MAY be used for purposes other than Traffic Engineering.
RFC 5316 clearly states that the TE Router IDs sub-TLVs in the Router Capability TLV were defined to advertise the TE Router IDs as per RFC 5305/RFC 6119 in cases where domain flooding scope is required - which the original TLVs cannot do. It therefore logically follows that the addresses advertised in the sub-TLVs of the Router Capability TLV have the same uses as the area scoped counterparts. So the premise on which your draft is written:
" TE Router ID sub-TLVs as defined in [RFC5316] ... are specifically designed for
   Traffic-Engineering (TE) purpose."
seems FALSE to me.

[Uma]: As the name itself suggests these are TE router IDs (The Traffic Engineering router ID TLV is TLV type 134 & The IPv6 TE Router ID TLV is TLV type 140) and
             yes these are  extended for domain scope in RFC 5316 as "TE Router ID sub-tlvs".
RFC 5305: TLV 134
" If a router does not implement traffic engineering, it MAY add or
   omit the Traffic Engineering router ID TLV.  If a router implements
   traffic engineering, it MUST include this TLV in its LSP.  This TLV
   SHOULD not be included more than once in an LSP."

So I don't think what is stated is FALSE.  These are indeed designed for TE. However I agree, any decent implementation generally  emit this TLV if a loopback is provisioned.


Please, let's not needlessly add confusion to the protocol by having multiple sub-TLVs which advertise the same information.

[Uma]: This is a good point. If a loopback is already advertised as "TE router ID TLV" then there is no point in advertising the same through these "Routable IP address" define.
             This can be explicitly stated.
             The point of the draft, as I see is to indicate one or more  routable IP addresses hosted by a node without having to tie up to the current TE Router IDs.