[ppml] Those pesky EUI-64's causing a shortage of IPv6

mack mack at exchange.alphared.com
Tue Jun 5 19:15:04 EDT 2007

EUI64 based on MAC addresses has a very specific format.
Effectively it only uses 47 bits.  There are 17 bits that are fixed with EUI64.
That means you can safely assign subnets in the parallel space.
As long as the 'local' bit of EUI64 is cleared, it isn't based on a MAC address.
So we only have 127 bits, can't everyone live with that?

BTW Vendor C ignores a portion of the IPv6 address in compressed mode.
Specifically bits 39:24 are removed.
Layer 4 information can only be used for filtering in compressed mode.
This is a much bigger issue from a practical standpoint.

This is going to limit real subnets to /87s for as long as the current hardware iteration is in place.
See the above comment about EUI64 using one bit, otherwise it would be /88s.

LR Mack McBride
Network Administrator
Alpha Red, Inc.

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