What is a routed prefix?

[Toucanfan]

Hi everyone!
The term is menioned a lot, but I can't seem to figure out what it means. A real world example: What is eg. the difference (if any) between my routed /64 and the tunnel connection /64 ?

Thanks in advance
:)

[lukec]

Your "tunnel connection /64" is being used in this situation as the netmask of yout point to point tunnel with HE. If you equate this in v4 parlance then this is being used as a /30 (your end and HE's end) no other IPv6 addresses can be used from that /64 (there goes another 18 trillion addresses :-[) If you really equate this with v4 then a /126 could be used, however HE use a /64 instead.

Your "routed /64" is a different IPv6 network that HE route down your tunnel for you to use at your location...hooray, you have 18 trillion addresses to play with and allocate to your hosts...

Does this help?

Regards
lukec

[Toucanfan]

Hi, and thank you for replying
I know that HE uses a /64 for the P-t-P connection. I've earlier been told that they do so because of some "compatibility issues". However, my question was more regarding the term "routed prefix". What does that exactly mean? Are there any non-routed prefix'es for instance?

[broquea]

Corrections:

You can use the other 18+ QUINTILLION IPs in the tunnel's PtP /64, but really only on the tunnel interface, and you get no rDNS control. So you are always better off leaving them be and using this routed prefix.

A /64 is 18,446,744,073,709,551,616 IPs, and not 18,446,744,073,709 so use quintillion please.

The routed prefix means that it is STATICALLY routed to your side of the tunnel, for your use on your LAN. This means the machine that you terminate the tunnel on will act as a router for that prefix.

[lukec]

Corrected corrections...being from the Great Britain... ;D

See the table referenced from the quote below... http://www.jimloy.com/math/billion.htm

Million, Billion, Trillion...
© Copyright 1999, Jim Loy

People sometimes ask me the names of the large numbers. Here is a table. The system used in the U.S. is not as logical as that used in other countries (like Great Britain, France, and Germany). In these other countries, a billion (bi meaning two) has twice as many zeros as a million, and a trillion (tri meaning three) has three times as many zeros as a million, etc. But the scientific community seems to use the American system.

A /64 would contain 18 zeros (rounded down) - a billion 12 and a million 6...
I question the "Internet Community" being the same as the "scientific community" and claim the right to call it 18 trillion...

Regards
lukec

[broquea]

Good thing then that HE.NET and myself are US based :)

[jimb]

I like saying ~18.4 billion billion (18.45 * 1000 ^ 3 * 1000 ^ 3), cause it sounds more impressive than "quintillion", and sounds like something Carl Sagan would say.   ;D

Anyways:

{root@gtoojimb/pts/0}~# units -v
2526 units, 72 prefixes, 56 nonlinear units

You have: 18446744073709551616
You want: quintillion
        18446744073709551616 = 18.446744 quintillion
        18446744073709551616 = (1 / 0.054210109) quintillion

You have: 18446744073709551616
You want: shortquintillion
        18446744073709551616 = 18.446744 shortquintillion
        18446744073709551616 = (1 / 0.054210109) shortquintillion
(US)

You have: 18446744073709551616
You want: longquintillion
        18446744073709551616 = 1.8446744e-11 longquintillion
        18446744073709551616 = (1 / 5.4210109e+10) longquintillion

You have: 18446744073709551616
You want: longtrillion
        18446744073709551616 = 18.446744 longtrillion
        18446744073709551616 = (1 / 0.054210109) longtrillion
(many non-english speaking countires)

/usr/share/units/units.def on your friendly Linux box has some nice comments on all this.

[cholzhauer]

BSD doesn't know what's going on

Code Select Expand


[carl@mars ~]$ units
586 units, 56 prefixes
You have: 18446744073709551616
You want: quintillion
unknown unit 'quintillion'


For the record, neither does Solaris

[jimb]

Older units.def files used "usquintillion" and "ukquintillion" etc.  Probably have an older version of units.

[lukec]

BSD knows...you just have to tell it ;-) gunits...install the port...even then note the difference in available "units" "prefixes" and "nonliniar units" available to BSD...< Linux  :(

Code Select Expand

lear:/usr/ports/math/units> gunits
2438 units, 71 prefixes, 32 nonlinear units

You have: 18446744073709551616
You want: brtrillion
        * 18.446744
        / 0.054210109
You have: 18446744073709551616
You want: quintillion
        * 18.446744
        / 0.054210109
You have:
lear:/usr/ports/math/units>


[jimb]

Kind of surprised that BSD ports version isn't as up to date as gentoo portage version of units.

[cholzhauer]

BSD knows...you just have to tell it ;-) gunits...install the port...even then note the difference in available "units" "prefixes" and "nonliniar units" available to BSD...< Linux

Ohh...gunits works better than units

Code Select Expand



[carl@mars ~]$ gunits
2526 units, 72 prefixes, 56 nonlinear units

You have: 18446744073709551616
You want: quintillion
        * 18.446744
        / 0.054210109


And BSD > Linux for some things...just depends what you want to do ;)