Subject: [Isis-wg] draft-ietf-isis-traffic-04.txt, MAX_PATH_METRIC

From: Neal Castagnoli <[email-masked]>
Date: Fri, 14 Sep 2001 10:54:00 -0700

I was checking the archives to find an answer to the question "why is
MAX_PATH_METRIC 2^32-2^25?", instead of what would appear to be more
reflective of the offered reasons behind the constant's choice, which would
be 2^32 - 2^24, or even 2^32-(2^24-1).

All I found was the same question, copied below, apparantly unanswered.

Does anyone know the reasoning?  Care to share it?

Thanks,

  --Neal

---------------------------------------------------------------

Hi:

In draft "IS-IS extensions for traffic engineeing":

"It is easiest to select MAX_PATH_METRIC such that
MAX_PATH_METRIC plus a single link metric does not
overflow the number of bits for internal metric
calculation.  We assume that this is 32 bits.  Thus,
MAX_PATH_METRIC is 4,261,412,864 (0xFE000000, 2^32 -
2^25)."

What does it mean "a single link metric does not
overflow the number of bits for internal metric
calculation."? Also where does it come from "2^25" in
the following statement?

Thanks.

_ming
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