[Lsvr] Need clarification on IGP-Metric TLV for LS Link Attributes in BGP-SPF deployments

[Pushpasis Sarkar <[e-mail]>]

Hi Authors,

I need a small clarification on how the Link IGP-Metric TLV (type 1095) for
the links originated by an BGP-SPF speaker look like. My doubt is
specifically on what would be the length of the metric value. For example,
following is the excerpt from RFC7752 section 3.3.2.4 which specifies the
length to be 1, 2 or 3 bytes for ISIS narrow-metrics, OSPF and ISIS
wide-metrics.

3.3.2.4.  IGP Metric TLV

   The IGP Metric TLV carries the metric for this link.  The length of
   this TLV is variable, depending on the metric width of the underlying
   protocol.  IS-IS small metrics have a length of 1 octet (the two most
   significant bits are ignored).  OSPF link metrics have a length of 2
   octets.  IS-IS wide metrics have a length of 3 octets.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |              Type             |             Length            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //      IGP Link Metric (variable length)      //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 21: IGP Metric TLV Format


What should be the length of the metric field when the origin is a BGP-SPF
speaker?

Looking forward to your clarification on this. Also it will be appreciated
a lot if a sentence or two can be added to the draft clarifying the above
in the next version.

Thanks and regards,
-Pushpasis