IPV6 PD Failure

[dainsbramaged]

I've been trying to acquire an ipv6 prefix from a Netgear LB1120 (LTE Modem) in bridge mode. When connected to the 3945E I have no success with any delegation techniques. When connected directly to a switch in the lan or  to a computer I manage to acquire ipv4 and ipv6. The 3945 is configured with functioning ipv4. Somehow I'm not able to find success with ipv6.

Obviously I am a novice.

I would like to try some examples provided by others.

[Harold Ritter]

Hi @dainsbramaged ,

Can you please share the 3945 WAN interface configuration.

Regards,

[dainsbramaged]

interface GigabitEthernet0/0
description PrimaryWANDesc_
ip address dhcp
ip nat outside
ip virtual-reassembly in
duplex auto
speed auto
ipv6 address prefix-from-provider ::1/56
ipv6 address autoconfig default
ipv6 enable
ipv6 dhcp client pd hint 2605:8D80:4C1::/56
ipv6 dhcp client pd ISP_PREFIX

[Harold Ritter]

Hi @dainsbramaged ,

Can you try the following:

interface GigabitEthernet0/0
description PrimaryWANDesc_
ip address dhcp
ip nat outside
ip virtual-reassembly in
duplex auto
speed auto

ipv6 address dhcp

ipv6 dhcp client pd ISP_PREFIX

Could you also provide a "show ipv6 int gi0/0" and "show ipv6 general-prefix" after changing the config.

Regards,

[dainsbramaged]

I have tried the recommendation and am still not able to receive a prefix.

The sh gen-prefix results in an indication that vlan1 is involved.

Router#sh ipv6 general-prefix
IPv6 Prefix ISP_PREFIX, acquired via DHCP PD
Vlan1 (Address command)

I then sh vlan1 and

Router#sh ipv6 int vlan1
Vlan1 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::7626:ACFF:FE34:3B04
No Virtual link-local address(es):
General-prefix in use for addressing
No global unicast address is configured
Joined group address(es):
FF02::1
FF02::2
FF02::1:FF34:3B04
MTU is 1500 bytes
ICMP error messages limited to one every 100 milliseconds
ICMP redirects are enabled
ICMP unreachables are sent
Input features: Common Flow Table Stile classification
Output features: Common Flow Table Stile Classification
ND DAD is enabled, number of DAD attempts: 1
ND reachable time is 30000 milliseconds (using 30000)
ND advertised reachable time is 0 (unspecified)
ND advertised retransmit interval is 0 (unspecified)
ND router advertisements are sent every 200 seconds
ND router advertisements live for 1800 seconds
ND advertised default router preference is Medium
Hosts use stateless autoconfig for addresses.
Router#

The sh int 0/0

Router#sh ipv6 int g0/0

results in no response.

I have tried this previously and had the same results.

Some how windows is able to acquire the ipv6 address from the modem ? or the the ISP ? Is the modem passing the ipv6 address through it and the request has to made to the ISP? Or does the ipv6 request have to be made to the modem. Either way I don’t know if 3945 is requesting from Modem or ISP and I don’t know how to specify the area of request. As previously mentioned the windows delegation somehow manages to succeed.

[dainsbramaged]

interface Vlan1
ip address 192.168.1.1 255.255.255.0
ip nat inside
ip virtual-reassembly in
ipv6 address ISP_PREFIX ::1:0:0:0:1/64

[Harold Ritter]

Hi @dainsbramaged ,

> Router#sh ipv6 int g0/0

That is weird given that you have configured ipv6 on that interface.

> Some how windows is able to acquire the ipv6 address from the modem ?

The workstation is most probably getting the its ipv6 address via stateless address auto configuration (SLAAC). Can you check who you getting the default route from and see if the MAC address matches the one from your modem. 

Regards,

[dainsbramaged]

It appears that the int g0/0 is requesting a prefix but does not get a reply. The sh ipv6 int g0/0 shows nothing probably because no reply was received.
Looking into the windows successful prefix request I could not find the source MAC for ipv6. Ipv4 appears to assisted (intercepted) by the modem but has a source MAC that is neither the Modem or windows interface. My assumption is that CG-NAT is in control. I’ve tried port forwarding without success. I would think that looking into the DHCP client cmds may be a direction.

[Georg Pauwen]

Hello,

if you connect your Windows PC directly to the modem, do you get both an IPv4 and an IPv6 address ?

I am thinking, since the modem is in bridge mode, you don't get anything from the modem as such, but from the ISP. Who is your ISP ?

[dainsbramaged]

Yes when the PC is connected to the modem (bridge mode) ipv4 and ipv6 are available.
My ISP is Rogers Canada.
Kenn

[Georg Pauwen]

Hello,

I have been looking around and found some forum posts and discussion from and with people that try to get IPv6 working on a Cisco router, without success. The general assumption is that Rogers does not support Cisco routers at all...can you check and verify with Rogers whether or not that is the case ?

[Harold Ritter]

Hi @dainsbramaged ,

If you are able to get an IPv6 address from SLAAC on the windows workstation, you should also be able to get one on the router. Please remove all ipv6 configuration from gi0/1, try the following configuration instead and provide a "show ipv6 int gi0/1" and "sh ipv6 general-prefix" after configuring it.

int gi0/1

ipv6 address autoconfig default
ipv6 nd ra suppress
ipv6 dhcp client pd ISP_PREFIX

Regards,