Re: Suggested Label Doubt

[Yangguang Xu <xuyg@lucent.com>]

Hello All,

Just want to use this thread to clarify one of my confusions of current GMPLS
signaling - "suggested label".

In my understanding, the purpose of "suggested label" is to speed up circuit
connection procedure by letting the upstream node to specify a label rather than
following the conventional MPLS signaling procedure that receiving the label in
the response.

My questions are:

(1) From a protocol design perspective, what's the benefit to suggest something
that could be declined?

(2) Label is of local significance. In optical network, labels are physically
bound, not logically bound. This is different from conventional IP network. This
is also why there is no difference of which node (upstream or downstream) to
choose the label in optical network. (Normally upstream and downstream node
share almost the same knowledge of links that connect them.)

(3) In optical transport network, a upstream node may decline a label from a
downstream node as a downstream node may decline a "suggested label" from a
upstream node. The rejections are of the same reasons and frequency.

    Why do we need to make the suggested label's operation so special? and not
necessary.

So I propose to change the semantic of the suggested label as such: (1) The
suggested label object/TLV is optional (2) However, if it is presented, it is
treated as the final decision. That is if the downstream node couldn't accept
the "suggested label", a connection rejection is responded.

I am looking forward to hearing your opinions.

Regards,

Yangguang