[ppml] Proposed Policy: IPv6 HD ratio
gih at apnic.net
Tue May 10 16:29:26 EDT 2005
>One of the critical factors in efficiency is the depth of the network
>hierarchy. For a cable system provider, the depth may be shallow, making
>it easy to fill up a stretch of addresses. For someone that is a wide
>area backbone provider, filling up the same stretch of addresses with
>hosts is harder.
>Question 1 - does the HD ratio inherently account for this? Regardless of
>the HD value that is. It's a log ratio...so maybe yes. If so, maybe it's
>just a question of what setting to use.
You can map a particular HD ratio setting to the concept of a network that
achieves a fixed efficiency setting at each level of internal hierarchy,
and adds an additional level of hierarchy each time the network by a factor
of n (for some value of n)
An HD ratio of 0.94 corresponds to a 75% efficiency at each internal level
of hierarchy, with a new level of hierarchy added when the network expands
by a factor of 32
An HD ratio of 0.8 corresponds to a 70% efficiency at each level with a new
level of hierarchy added each time the networks grows by a factor of 8.
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