Dual-stack PPP requires two separate sessions?

A while ago a senior Service Provider network designer told me that they have serious issues with IPv6 deployment as IPv6 requires a separate PPPoE session from the CPE devices which significantly increases their licensing costs. The statement really surprised me; PPP was designed to be a multi-protocol environment and it’s very easy to configure IPv4 and IPv6 over a single PPP session in Cisco IOS. I think I might have tracked down the source of this “information” to the 6deploy IPv6 and DSL presentation which states on Page 11 that “Separate PPP sessions are established between the Subscriber’s systems (or CPE) and the BBRAS for IPv6 and IPv4 traffic”.

Being too Cisco-centric, I cannot figure out whether this claim has any merit, as it clearly does not apply to Cisco IOS. Are there really boxes out there that are so stupid that they cannot run two protocols across a single PPPoE session?


  1. It might be worth touching base with the ISP I use as they are currently doing a dual stack PPP trial with their adsl clients.


    They already found one interesting bug where if the client did an IPv6 only PPP session their Cisco LNS would not send radius accounting updates...
  2. What i understood from a Juniper IPV6 seminar is that you can choose between dual stack PPP or two ppp sessions one for ipv4 and the other for ipv6. With dual stack ppp only one session is used.
  3. I would love to see a sample configuration for dual-stack including how to dynamically assign IP's from a "pool" like in IPv4 - anyone up for the challenge? ;)
  4. Hi Paul & Frank,

    Hope it is you expected

    LNS site:
    interface Virtual-Template1
    ip unnumbered Loopback0
    ipv6 address autoconfig
    peer default ip address pool pool-lns
    peer default ipv6 pool ipv6pool-lns
    ip local pool pool-lns
    ipv6 local pool ipv6pool-lns 2001:E00:F::/48 64

    Dialer/client/CPE site:
    interface Dialer99
    ip address negotiated
    ip mtu 1492
    encapsulation ppp
    dialer pool 1
    dialer idle-timeout 0
    dialer persistent
    ipv6 address autoconfig default
    ipv6 enable
  5. Thank you, you're fantastic.
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