RE: questions in LMP (draft-ietf-ccamp-lmp-08)

["Gudipalli, Sugadeesh" <sugadeeshg@netplane.com>]

Jonathan,

      Thanks for the quick response, The following sentence you
sent is still not clear to me.

"LMP link verification procedure is a mechanism that can be used to
dynamically bind the local/remote identifiers."
                     ^^^^^^^^^^^^^^^^^^^^^^^^^
What identifiers, if they are component id,port id or interface id there is
no issue. I have an issue only regarding TE link id.

Thanks for clarifying that property correlation need not be done
before link verification, then what is the use of "Link
Verification Supported" flag  in the linksummary message which is
sent after the link verification procedures are already done for the TE
link.

In 7.Message_Id Usage section there is no discussion of message id for
BeginVerify Message but it has <MESSAGE_ID> field in it. Do we have to
ignore the message id field. If not since this is TE link specific
message, we will be needed to identify the local TE link for
message id validation when a beginverify is received. If the mapping is
already not configured on the two nodes for TE links, the identification
of the local TE link id when beginverify arrives with no
REMOTE_LINK_ID will be impossible.

Please clarify 

Regards
Sugadeesh

-----Original Message-----
From: Jonathan Lang [mailto:Jonathan.Lang@RinconNetworks.com]
Sent: Monday, April 07, 2003 10:22 PM
To: 'Gudipalli, Sugadeesh'; ccamp@ops.ietf.org; jplang@ieee.org
Subject: RE: questions in LMP (draft-ietf-ccamp-lmp-08)


Sugadeesh,

> -----Original Message-----
> From: owner-ccamp@ops.ietf.org [mailto:owner-ccamp@ops.ietf.org] On
Behalf
> Of Gudipalli, Sugadeesh
> Sent: Monday, April 07, 2003 5:16 AM
> To: 'ccamp@ops.ietf.org'; 'jplang@ieee.org'
> Cc: Gudipalli, Sugadeesh
> Subject: questions in LMP (draft-ietf-ccamp-lmp-08)
> 
> Hi Lang and all,
> 
>        Are the link verification procedures required to generate
automatic
> remote TE link id and
> local TE link ID  mapping along with the local interface id and remote
> interface id mapping.
LMP link verification procedure is a mechanism that can be used to
dynamically bind the local/remote identifiers.

> I got the above understanding from the following statement:
> 
> "5. Verifying Link Connectivity In this section, an optional procedure
is
> described that may be used
>  to verify the physical connectivity of the data links and dynamically
> learn (i.e., discover) the TE link and Interface_Id associations. "
> 
> 
> From my understanding of the LMP spec the mapping of the remote and
local
> TE-link ID can't be discovered it needs to be configured,
you misunderstand the procedure.  See below.

> due to the following points:
> 
> i)
>   "Support for this procedure is indicated by setting the "Link
>    Verification Supported" flag in the TE_LINK object of the
>    LinkSummary message."
The next sentence says:
"  If a BeginVerify message is received and link verification is not
   supported for the TE link, then a BeginVerifyNack message MUST be
   transmitted with Error Code indicating, "Link Verification Procedure
   not supported for this TE Link."
You do not need to send a LinkSummary message before you send a
BeginVerify message.

> 
> If the remote TE link ID is not mentioned in the link summary message
sent
> to the remote node with the verification supported flag set,
This is not allowed.  See Section 13.11.

> how will the
> remote
> node identify for which local TE-link id link verification procedure
is
> supported.
> Since there is no 1 to 1 map between the control channel and TE link,
the
> remote node has no way of identifying the TE-link for which this link
> summary message is addressed.
> 
> ii)
> "If the message is a LinkSummary message and the Message_Id value is
>    less than the largest Message_Id value previously received from the
>    sender for the TE Link, then the message SHOULD be treated as being
>    out-of-order."
> 
> If the remote TE link ID is not mentioned in the link summary message
sent
> to the remote node,
This is not allowed.  See Section 13.11.

> how will the remote node identify for which local
> TE-link id
> the message id in the linksummary has to be verified.
> Since there is no 1 to 1 map between the control channel and TE link,
the
> remote node has no way of identifying the TE-link for which this link
> summary message is addressed. Also for sending the linksummaryack or
> linksummarynack you need the message id specific to the local TE link,
> which
> we can't identify if the remote link id is 0.
> 
> 
> Can you please clarify.
Hope this helps.

-Jonathan

> 
> 
> Regards
> Sugadeesh