ISP DHCPv6 vs SLACC for WAN assignment


There is a bit of a debate at the moment (company internal) on the best way to deploy an IPv6 address to our WAN CPE clients from the PE.

SLAAC vs DHCPv6 on WAN

(Esentially we are sending down IPv6 PD pool to the CPE's anyway where they can dish out SLAAC leases to their clients, like xbox or whatever.)

We have labbed 2 senerios for assigning the WAN IP. Stateless - SLAAC and statefull - DHCPv6

Either works as the PD pool config is the same, except DHCPv6 doesnt advertise a default route, but its not really an issue as our provisioning procedure will inject that anyway.

I just wanted to get peoples opinion on their experiance in deploying IPv6 down to the CPE's (WAN) for a SP. Which works best, Stateful or Stateless?

Is it easer for you to track who gets what with the v6 server? or doesnt it really matter so much. Thoughts?


Comments

  • When you said DHCPv6, I suppose you mean "Stateful DHCPv6". Unfortuately, you can't simply replace SLACC with DHCPv6. DHCPv6 behaves differently than DHCPv4. I don't know the rationale behind IETF decision. Two things you need to keep in mind for Stateful DHCPv6:

    1. DHCPv6 IA_NA only contains Prefix Option, it doesn't contain Default Gateway. The device must still rely on SLACC to learn the default gateway if you don't want to statically set it up.
    2. DHCPv6 IA_NA Prefix Option doesn't contain "Prefix Len". In the recent ietf-dhc working group mailing-list, people were debating the prefix len should be /128. If this is the case, the prefix learned from DHCPv6 would be a host route. Host route alone can't really go anywhere.

    HTH

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