[AusNOG] ipv6, dhcpv6 pd and dsl/dial termination

Tim Warnock timoid at timoid.org
Sun Feb 14 00:20:56 EST 2010

Hey all,

Earlier today I was playing around with local DHCPv6 Prefix Delegation pools
for IPv6 to the customer on a Cisco LNS.

In the hopes of:
a) checking to see that my thought process is sane
b) trying to encourage more ISPs to try IPv6 to the customer.

In that spirit here is a bit of a "mini howto". Feedback is definitely

Ideas here were inspired by the lads over at internode. I've not seen their
configuration however.

! give out a /64 out of a /48 for the PPP link
ipv6 local pool PPP-POOL 0000:0000:100::/48 64

! this is where dhcpv6 clients will pull a /62 from
ipv6 local pool ISP-PD 0000:0000:101::/48 62

ipv6 dhcp pool PPP-POOL
 ! I just made up some numbers for the ttls.
 prefix-delegation pool PPP-POOL lifetime 86400 14400
 ! dont know whether this is useful or not on the PPP link itself (being
that the PPP link is stateless auto configured):
 ! dns-server 0000:0000::101
 ! dns-server 0000:0000::102

ipv6 dhcp pool ISP-PD
 ! You could use infinity to issue "static" allocations (this is local to
the LNS but)
 ! Although I would figure that doing IPv6 framed routes or something out of
RADIUS would be better for true statics...
 ! Again, I just made up some numbers for the ttls.
 prefix-delegation pool ISP-PD lifetime 86400 14400
 ! issue your ipv6 dns servers here
 dns-server 0000:0000::101
 dns-server 0000:0000::102

finally on your virtual template:
int virtual-template x
 ipv6 enable
 ipv6 address autoconfig
 ipv6 unnumbered FastEthernetX || LoopbackX (set the same as v4 I guess?)
 no ipv6 nd ra suppress
 ipv6 dhcp server ISP-PD rapid-commit
 peer default ipv6 pool PPP-POOL

Router#test Virtual-Template X subinterface
Subinterfaces may be created using Virtual-TemplateX

The commands used don't appear to affect the ability to create virtual
template subinterfaces.

Routes should show up as connected, and you could put in hold-up routes if
you wanted.

For the client end:
int diX
 ipv6 enable
 ipv6 address autoconfig
 ipv6 dhcp client pd ISP-PD rapid-commit

int vlan1 || int fas0/0
 ipv6 address ISP-PD ::1/64
 ipv6 enable

Using RADIUS some of this info could be pushed out via Cisco-AVPairs.


Sites I drew inspiration from:

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