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noaccess

@hosting.com

ipv6 subnetting question

Hi, can someone explain how to break a /64 from 2001:DB8::/32?

Thx



bobrk
You kids get offa my lawn
Premium
join:2000-02-02
San Jose, CA

Does the subnetting even do anything? I set up a network with both /64 and /32 and I can see everything.



Thomas Schf

@t-dialin.net
reply to noaccess

e.g.


2001:DB8::/64
2001:DB8:0:1::/64
2001:DB8:0:2::/64



noaccess

@hosting.com
reply to bobrk

i just want to know how it is done



tschaefer

@t-dialin.net
reply to bobrk

said by bobrk:

Does the subnetting even do anything?

Of course!

One /32-net has 32 /64-nets inside.


tschaefer

@t-dialin.net
reply to noaccess

How do you split subnets in IPv4?

By configuring your routers and hosts.
Sub-netting is nearly the same as in the old protocol.
You have more bits, write the mask-length every time with "/xx" and usually you don't split /64 for LANs.



leibold
Premium,MVM
join:2002-07-09
Sunnyvale, CA
kudos:10
Reviews:
·SONIC.NET
reply to tschaefer

said by tschaefer :

One /32-net has 32 /64-nets inside.

Just a few more then 32

How does approximately 4 billion sound ?

A /32 prefix has 32 bits left over for subnetting (assuming /64 subnets). 32 bits allow for 4294967296 subnets.
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tschaefer

@t-dialin.net

Sorry 2^32 subnets.



cablegeek01

join:2003-05-13
USA
kudos:1

2 recommendations

reply to noaccess

Take your 2001:db8::/32, and start splitting off /64 networks.
Remember, an IPv6 address has 64b for the network prefix, and 64b for the interface ID (host), so:
x:x:x:x:y:y:y:y = x for network, and y for interface id (host)

One addressing scheme would be to subnet the /32 by region and local subnet, so you'd have:
x:x:y:z where x is your /32 parent block, y is your /48 region id (0-ffff), and z is your /64 subnet id (0-ffff).

The remaining 64bits are your interface ID (host IP), and will be assigned via SLAAC, or DHCPv6 if you don't opt for static IP addressing.

That gives you 65,000 regions, and 65,000 subnets in each region.

For the below examples, we'll start with region 0, subnets 0 through 2.

Region 0 subnets 0-2
2001:0db8:0:0:0:0:0:0 through 2001:0db8:0:0:ffff:ffff:ffff:ffff =/64 #1
2001:0db8:0:1:0:0:0:0 through 2001:0db8:0:1:ffff:ffff:ffff:ffff =/64 #2
2001:0db8:0:2:0:0:0:0 through 2001:0db8:0:2:ffff:ffff:ffff:ffff =/64 #3 etc

Region 1 subnets 0-2
2001:0db8:1:0:0:0:0:0 through 2001:0db8:1:0:ffff:ffff:ffff:ffff =/64 #1
2001:0db8:1:1:0:0:0:0 through 2001:0db8:1:1:ffff:ffff:ffff:ffff =/64 #2
2001:0db8:1:2:0:0:0:0 through 2001:0db8:1:2:ffff:ffff:ffff:ffff =/64 #3 etc

If you followed it to the end, it would go all the way up to 2001:0db8:ffff:ffff:ffff:ffff:ffff:ffff

Does that make sense?