Re: I-D ACTION:draft-shiomoto-ccamp-lsp-hierarchy-bis-00.txt

["Igor Bryskin" <ibryskin@movaz.com>]

Hi,



I believe the draft could be very useful. I have several suggestions that
IMO would make it stronger.



  1.. It is possible that the same H-LSP is advertised into several control
planes (for example, L1VPN provider H-LSP could be advertised into several
VPNs in the Virtual Link mode) each time with different link IDs (possibly
sometimes as numbered and sometimes as unnumbered). This fact could be
negotiated between the H-LSP ends by including several
LSP_TUNNEL_INTERFACE_ID objects (one per target control plane) into
Path/Resv message. I've probably missed it, but I didn't see anywhere in the
draft an explicit statement of such possibility.
  2.. There are no currently any signaling mechanisms for negotiating how
parallel H-LSPs should be bundled together before advertising them as a TE
link. Normally, such negotiation is provided via LMP. However, you suggest
(and rightfully so) to avoid using LMP for TE links based on H-LSPs, hence,
all negotiations should be achieved via signaling. Note that bundling
schemes could be different for each target control plane. One way of
achieving this is by introducing a new sub-TLV of the
LSP_TUNNEL_INTERFACE_ID object - let's call it BUNDLE sub-TLV - and have the
ends of the H-LSPs to bundle those H-LSPs which share the same bundle ID for
the same target control plane. Note also that bundle ID could be used as a
link ID when advertising the bundle as a single TE link
  3.. H-LSP does not necessarily have to be advertised as a TE link into any
control plane. For instance, an H-LSP could be used as a dedicated
protection for some other H-LSP or as a data link for a higher layer LSPs
(note that not all data links are advertised as TE links). However, in order
for such H-LSP to be capable to nest other LSPs the ends of the H-LSP need
to know at least that the LSP is intended to be used as H-LSP (that is,
resources will be dynamically allocated within the LSP)  as well as remote
link IDs (otherwise, it would impossible to map the information in the PHOP
object with the local end of the link). Again, usually this is the job of
the LMP. One way to signal an H-LSP that needs not to be advertised into any
control plane is to specify some special value (e.g. NULL) as a target
control plane ID.


Regards,

Igor