ipv6 create pools from pool delegated by ISP

oxtan · Sun Mar 12, 2023 11:30 am

hi,
My ISP (KPN, The Netherlands) provides me with a /48 using prefix delegation. I can see it using this configuration:

/ipv6 dhcp-client
add add-default-route=yes interface=pppoe-client pool-name=delegated_by_kpn pool-prefix-length=48 prefix-hint=::/60 rapid-commit=no request=prefix use-peer-dns=no

And I can see the pool gets dynamically added:

/ipv6 pool> print 
Flags: D - dynamic 
 #   NAME                                                                                            PREFIX                                      PREFIX-LENGTH EXPIRES-AFTER       
 0 D delegated_by_kpn                                                                                2a02:a45c:xxx::/48                                     48 2d23h50m22s

So now I want to create a pool from this delegated pool:

/ipv6 pool> add name=vlan6 prefix=2a02:a45c:xxx:6::/64 prefix-length=64
failure: prefix of two pools cannot overlap!

Is it possible to create subnets from the delegated pool? How? I am a bit confused now.

Emil66 · Sun Mar 12, 2023 11:58 am

The "pool-prefix-length" is meant to be the length of the prefixes which you want to draw from the address pool, not the prefix length that your ISP assigns. Most of the time, you want those address ranges to be significantly smaller (bigger prefix length), so that you have multiple prefixes that can be assigned to separate subnets. If you do not need to delegate prefixes to other routers which in turn need several prefixes, you should probably use a pool-prefix-length of 64. Then you can draw from the pool wherever you need an IPv6 prefix, for example "/ipv6 address".

oxtan · Sun Mar 12, 2023 12:35 pm

so I could do this If I had other routers behind my router but not when using just one router. Yes, I can see how that would work in a larger network

, but it is a bit disappointing to not be able to define the pools manually.

I can indeed assign an address to every vlan address, and then the autodiscovery will distribute to the rest of the devices.

Thanks for your answer.

Emil66 · Sun Mar 12, 2023 12:42 pm

It becomes a bit complicated, or rather impossible, if you have a need for prefixes with different lengths, because the pool can have just one pool-prefix-length and you can't take a chunk out of the pool to create a "sub" pool with a different prefix length. So if you need /60 prefixes for prefix-delegation to other routers, you cannot assign /64 prefixes from the same pool to directly attached networks. Though if you have enough addresses, you can simply assign /60 prefixes also to LANs. It's "wasteful", but you weren't going to use the full /48 anyway, were you?

oxtan · Sun Mar 12, 2023 1:13 pm

no, no, I do not intend to have 65000 subnets at home.

, at least, you never know ...
I guess I expected something before I fully understood how it should be working, so now I have adapted my expectation and have a working setup and understand how to go from here.
Thanks again.

ipv6 create pools from pool delegated by ISP [SOLVED]

ipv6 create pools from pool delegated by ISP

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Re: ipv6 create pools from pool delegated by ISP

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