Re: [irtf-discuss] Why do we need to go with 128 bits address space ?

[Masataka Ohta <[e-mail]>]

Fernando Gont wrote:

 > The specific 128-bit value seems to be a compromise between two
 > proposals
 >  
(https://www.lacnic.net/innovaportal/file/2578/1/ipv6-latnic2018-hinden-01.pdf)...
 > but I won't speak for Bob. ;-)

That is an inappropriate explanation. As variable length address
is not adopted, among three reasons for TUBA on slide 13:

	Compatible with OSI NSAP address plans
	Large enough for auto-configuration using IEEE 802 addresses
	Could start with short addresses and grow later

only

	Large enough for auto-configuration using IEEE 802 addresses

remains.

That is, IPv6 address unnecessarily became 128bit long, merely
because of poor idea of so stateful SLAAC.


Phillip Hallam-Baker wrote:

 >> e) 64 isn't enough to allow lots of bits for topology plus
 >> lots of bits for privacy

is a typical misunderstanding by those who do not know 32 bit
IPv4 address is enough to represent hierarchical topology of
the Internet today.

 >The reason we went to 128 bits was 64+64 = 128

> It was assumed that networks would want to map MAC addresses onto the lower
> bits of the address and those were already in the process of expanding to
> 64 bits.

No, the reason is because I pointed out that MAC address of IEEE1394
is already 64bit long. Before that, it was 80+48.

> This hasn't happened because it is nonsense. Disclosing the
> structure of your internal network to potential attackers is stupid.

Wrong.

Extending MAC address 64 bit has nothing to do with internal topology.

							Masataka Ohta