IPv6 over dialer and Radius

[sebastien3]

Hello,

On an 800 series router I have the following error in the logs :

%IPV6_ND-4-OLPFXCON: Prefix 2001:db8:aaaa:0012::/64 advertised in RA on Dialer0 has been previously configured on another interface

The router configuration is as follows :

interface Dialer0
 description *** PPPoE ***
 mtu 1492
 ip address negotiated
 no ip redirects
 no ip unreachables
 no ip proxy-arp
 ip mtu 1452
 ip nat outside
 ip virtual-reassembly in
 encapsulation ppp
 ip tcp adjust-mss 1412
 dialer pool 1
 dialer-group 1
 no cdp enable
 ipv6 address autoconfig
 ipv6 enable
 ipv6 mtu 1422
 ipv6 nd prefix default no-advertise
 ipv6 nd ra lifetime 0
 ipv6 tcp adjust-mss 1362
 ppp authentication chap callin
 ppp chap hostname XXXXX
 ppp chap password 7 ZZZZZZ
end
!
interface Vlan1
 ip address 192.168.1.1 255.255.255.0
 no ip redirects
 no ip unreachables
 no ip proxy-arp
 ip nat inside
 ip virtual-reassembly in
 ipv6 address 2001:db8:aaaa:0012::0001/64
 ipv6 enable
 ipv6 nd prefix default no-advertise
 ipv6 nd other-config-flag
 ipv6 nd ra lifetime 0
 no ipv6 redirects
 no ipv6 unreachables
 ipv6 dhcp server 2001:db8:aaaa:0012::0001::
end
!
no ipv6 source-route
ipv6 unicast-routing
ipv6 cef
ipv6 dhcp pool 2001:db8:aaaa:0012::0001::
 address prefix 2001:db8:aaaa:0012::/64 lifetime infinite infinite
 link-address 2001:db8:aaaa:0012::0001/64
 dns-server 2001:4860:4860::8888
 domain-name lab.local
!

On my RADIUS I have this configuration for the user pppoe :

        Cisco-AVPair = "lcp:interface-config#1=ip unnumbered Loopback10",
        Cisco-AVPair = "lcp:interface-config#2=ipv6 enable",
        Cisco-AVPair = "lcp:interface-config#3=ipv6 unnumbered Loopback10",
        Cisco-AVPair = "lcp:interface-config#4=no ipv6 nd suppress-ra",
        Cisco-AVPair = "ipv6:prefix=2001:db8:aaaa:0012::0001/64",

The IPv6 connection is working, I can ping IPv6 resources (ping 2001: 4860: 4860 :: 8844 source vlan 1).

I cannot figure out the error %IPV6_ND-4-OLPFXCON, and is my configuration correct ?

Thank you !

[marce1000]

 - Ref : https://www.cisco.com/c/en/us/td/docs/ios/system/messages/guide/sm_cn05.html?dtid=osscdc000283

 >...

%IPV6_ND-4-OLPFXCON : Prefix %P/%d advertised in RA on %s has been previously configured on another interface

Explanation    This warning indicates that an on-link prefix advertised in an IPv6 ND RA on the specified interface has previously been configured on another interface. The prefix will be ignored on the current prefix

Recommended Action    Learning an on-link prefix via IPv6 ND RA when the same prefix has previously been configured on another interface indicates a likely configuration error, either on the current router or on the neighbor router advertising the ND RA. Review network topology, current router and adjacent router configuration, and correct as appropriate

M.

[sebastien3]

It doesn't help me on the problem anymore...

If I remove Cisco-AVPair = "ipv6:prefix=2001:db8:aaaa:0012::0001/64", from the RADIUS part I can no use IPv6 !

I cannot identify where is the configuration problem on the IPv6 portion of the 800 router.

[Harold Ritter]

Hi @sebastien3 ,

The issue is due to the fact that you are using the same prefix (2001:db8:aaaa:0012::/64) on both the vlan interface and the dialer interface. You need to change one of them.

Regards,