[c-nsp] IPv6 - Frame-Interface-Id attribute (static addressing for PPP sessions)

[vikas hazrati]

Hello all

I am trying to create an initial configuration for IPv6 router that
terminates PPP subscriber sessions. I am experimenting with static
addressing and so
far I am not sure about the role of "Framed-Interface-Id" Radius attribute.

I use the following config in the LNS:

interface Virtual-Template100
 ip unnumbered Loopback46
 ipv6 unnumbered Loopback46
 no ipv6 nd prefix framed-ipv6-prefix
 ipv6 nd other-config-flag
 no ipv6 nd ra suppress
 ipv6 dhcp server LAN
 peer default ip address pool v4_PPPO_POOL
 peer default ipv6 pool v6_PPPO_POOL
 ppp authentication pap
 ppp ipcp dns 10.0.1.1
end

ipv6 local pool v6_PPPO_POOL 2001:100::/64 128 shared

The subscribers in the normal operation are assigned a /128 address using
the prefix 2001:100::/64 (from the pool). The lower 64bits of the
subscribers
ppp interface is based on the CPEs / Dialer link local address.

I try to find a way to be able to staticaly define the interface-id portion
(lower 64 bits)
of the address that is assigned to the subscribers PPP interface.
I was hoping that this would be achieved by using the
"Framed-Interface-Id"Radius Attribute.

If I use Framed-Interface-Id="1111:1111:1111:1111", indeed during ppp
negotiation
the interface ID reaches the CPE

(output for CPE debug ppp negotiation)

*Jul 24 15:54:53.587: Vi2 IPV6CP: O CONFREQ [Closed] id 1 len 14
*Jul 24 15:54:53.587: Vi2 IPV6CP:    Interface-Id C801:0FFF:FE80:0008
(0x010AC8010FFFFE800008)
*Jul 24 15:54:53.587: Vi2 PPP: Process pending ncp packets
*Jul 24 15:54:53.595: Vi2 IPCP: I CONFREQ [Not negotiated] id 1 len 10
*Jul 24 15:54:53.595: Vi2 IPCP:    Address 163.1.2.3 (0x0306A3010203)
*Jul 24 15:54:53.599: Vi2 LCP: O PROTREJ [Open] id 2 len 16 protocol IPCP
(0x80210101000A0306A3010203)
*Jul 24 15:54:53.599: Vi2 IPV6CP: I CONFREQ [REQsent] id 1 len 14
*Jul 24 15:54:53.599: Vi2 IPV6CP:    Interface-Id C800:0FFF:FE80:0008
(0x010AC8000FFFFE800008)
*Jul 24 15:54:53.599: Vi2 IPV6CP: O CONFACK [REQsent] id 1 len 14
*Jul 24 15:54:53.599: Vi2 IPV6CP:    Interface-Id C800:0FFF:FE80:0008
(0x010AC8000FFFFE800008)
*Jul 24 15:54:53.607: Vi2 IPV6CP: I CONFNAK [ACKsent] id 1 len 14
*Jul 24 15:54:53.607: Vi2 IPV6CP:    Interface-Id 1111:1111:1111:1111
(0x010A1111111111111111)
*Jul 24 15:54:53.607: Vi2 IPV6CP: O CONFREQ [ACKsent] id 2 len 14
*Jul 24 15:54:53.607: Vi2 IPV6CP:    Interface-Id 1111:1111:1111:1111
(0x010A1111111111111111)
*Jul 24 15:54:53.615: Vi2 IPV6CP: I CONFACK [ACKsent] id 2 len 14
*Jul 24 15:54:53.619: Vi2 IPV6CP:    Interface-Id 1111:1111:1111:1111
(0x010A1111111111111111)
*Jul 24 15:54:53.619: Vi2 IPV6CP: State is Open
*Jul 24 15:54:53.623: Vi2 IPV6CP: Reseting link-local address.
*Jul 24 15:54:53.623: ICMPv6-ND: Create Static Neighbour
FE80::C800:FFF:FE80:8 on Dialer100

But the CPE still bases its address to its own interface-id
C800:0FFF:FE80:0008

CPE

show ipv6 interface brief

Dialer100                  [up/up]
    FE80::C801:FFF:FE80:8
    2001:100::C801:FFF:FE80:8

On the other hand the LNS seem to be able to interpret the interface-id form
radius

C   2001:100::1111:1111:1111:1111/128 [0/0]     <----- It takes into account
the Framed-interface-id
     via Virtual-Access3, directly connected
S   2046::/64 [1/0]
     via FE80::C801:FFF:FE80:8, Virtual-Access3


The question is what is the role of the "Framed-Interface-Id" attribute, can
it be used to make the CPE
choose a specific Interface-Id address for the PPP session.
If not is there a proposed way to statically assign an IPv6 address to a
subscriber's PPP intreface?


Regards