I am trying to push out IPv6 unnumbered to an interface via radius. I am trying to do it in a similar fashion to how you would for IPv4:

Cisco-AVPair += "ip:vrf-id=vrf-name",
Cisco-AVPair += "ip:ip-unnumbered=Loopback301",

I am trying to assign a user into a VRF and of course that part is easy, but when you put a VRF on an interface it gets rid of any IP addressing, hence the need for the unnumbered interface commands. I can push the IPv6 configuration easily with the lcp:interface-config command:

Cisco-AVPair += "lcp:interface-config#1=ipv6 unnumbered loopback301",

But that has the adverse side effect of needing to support sub-interfaces:

%FMANRP_ESS-4-FULLVAI: Session creation failed due to Full Virtual-Access Interfaces not being supported. Check that all applied Virtual-Template and RADIUS features support Virtual-Access sub-interfaces. swidb= 0x7FF07FD32098, ifnum= 91

I would rather avoid enabling this functionality for the sake of the scalability drop that occurs on the BRAS. (I do know how, if it does come to that! :))

I am wondering if anyone knows a way of pushing out the above IPv4 unnumbered command for IPv6 so I can keep using full virtual access interfaces?

Note: I do know that for IPv6, I don't technically need an address on the BRAS side of things, or CPE for that matter, as it works over the link-local. In this case, I do need an address as DHCPv6 seems to only work when one is configured.

Edit: This is on a Cisco ASR platform running XE.

  • Does anyone use IPv6? They've been talking about it since 2001 or earlier but I have not seen in in production yet? Does anyone use it? Commented May 25, 2015 at 3:13
  • We run dual stack across the service provider network. Many content providers use ipv6 as well, facebook, google, youtube, to name a couple. One of the big issues to implementation is that end customers just want the interwebs to work. They don't really care how. The other issue is IPv4 exhaustion. This has lead to many service providers opting to implement CGNAT. This has kept customers happy as they can just do internet things, and it means they use less IP addresses. IPv6 is the way forward, which is why we have done dual stack on our network. BRAS functionality is something Im fine tuning.
    – Firebirdnz
    Commented May 25, 2015 at 3:59
  • 2
    @RonRoyston Take a look at google.de/ipv6/statistics.html#tab=per-country-ipv6-adoption Many of the big access provides will handout IPv6 because we run out of IPv4 addresses. Most probably these providers will use NAT for v4 and several customers will share one IPv4 address.
    – user2084
    Commented May 25, 2015 at 7:37
  • It's not so flexible but can you put that config into the virtual-template interface, or do you have many loopbacks you need to dynamically use?
    – Baldrick
    Commented Feb 6, 2016 at 19:16
  • @jwbensley Yes I have many loopbacks that I need to use dynamically. I also have the issue that when you assign a vrf via radius it strips the interface configurations.
    – Firebirdnz
    Commented Feb 8, 2016 at 7:53

1 Answer 1


Have a look @ http://blog.ipspace.net/2011/09/ipv6-mplsvpn-6vpe-with-pppoe-and-radius.html

Is this what you are trying to achieve?

They confirm that:

Cisco-AVPair += "ip:vrf-id=vrf-name",
Cisco-AVPair += "ip:ip-unnumbered=Loopback301"

would only work with IPv4.

In order to make IPv6 work, you would need the following:

cisco-avpair += "lcp:interface-config#1=ipv6 unnumbered Loopback 1001"
  • This does in fact work. My question was whether there was a way to do this without having to use lcp:interface-config. Doing it that way requires turning on "aaa policy interface-config allow-subinterface".
    – Firebirdnz
    Commented Aug 5, 2016 at 3:26

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