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RSVP LABEL value

From: "Hong Liao" <hliao@telcordia.com>
Date: Wed, 12 Dec 2001 17:16:49 -0500
X-MIMETrack: Serialize by Router on notes640/Telcordia(Release 5.0.6a |January 17, 2001) at12/12/2001 05:17:04 PM

Hi,

I have questions for the rsvpte label value.

According to the draft the tunnel 09.txt section 4.1 , the contents of a
LABEL is a single label, and encoded in 4 octets.
Each generic MPLS label is an unsigned integer in the range of through
1048575.  -----> here it does not meantion the reserved label value.

Suppose there is engress router, is it correct for the Egress router to
send a resv msg with the label value to be '00000001'O?
I think it is OK as far as it is within the range as mentioned in the
draft.

But how about the RFC3202. section 2.1, it mentioned the value for the
label value:

There are several reserved label values:

           i. A value of 0 represents the "IPv4 Explicit NULL Label".
              This label value is only legal at the bottom of the label
              stack.  It indicates that the label stack must be popped,
              and the forwarding of the packet must then be based on the
              IPv4 header.

          ii. A value of 1 represents the "Router Alert Label".  This
              label value is legal anywhere in the label stack except at
              the bottom.  When a received packet contains this label
              value at the top of the label stack, it is delivered to a
              local software module for processing.  The actual
              forwarding of the packet is determined by the label
              beneath it in the stack.  However, if the packet is
              forwarded further, the Router Alert Label should be pushed
              back onto the label stack before forwarding.  The use of
              this label is analogous to the use of the "Router Alert
              Option" in IP packets [5].  Since this label cannot occur
              at the bottom of the stack, it is not associated with a
              particular network layer protocol.

Then if that is the case, the 1 is the reserved one, it is not correct to
sent out the resv msg with label value '00000001'O or not?

Thanks,
Julia