IPv6 Autoconfig on a Cisco Router - default gateway not being installed

[danielseijas3010]

Hi!,

I am testing the below scenario on GNS3 with two virtual 3600 chassis:

 3600 Software (C3640-IK9O3S-M), Version 12.4(13)

R2(fa0/0) is intended to be the default gateway for R1. I have configured fa0/0 on R1 as "autoconfig" and it is working in the sense that it is autoconfiguring itself with global unicast ipv6 IP for the right ipv6 prefix, but there is no default gateway being installed on R1. Any idea why? the only thing I am thinking of is that R2 itself does not have a default route yet... but not sure if that matters. See configurations of interest below

R1#show run

### omitting other pieces of config ###

ipv6 unicast-routing

interface FastEthernet0/0
   no ip address
   duplex auto
   speed auto
   ipv6 address autoconfig
   ipv6 enable

R2# show run

###omitting other pieces of config###

ipv6 unicast-routing

interface FastEthernet0/0
   no ip address
   duplex auto
   speed auto
   ipv6 address 2001:12::/64 eui-64
   ipv6 enable

______________________

See that fa0/0 on R1 is getting an IP but not installing a default route:

R1#show ipv6 interface fastethernet 0/0
FastEthernet0/0 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::CE02:83FF:FE64:0
Global unicast address(es):
2001:12::CE02:83FF:FE64:0, subnet is 2001:12::/64 [PRE]
valid lifetime 2591882 preferred lifetime 604682
Joined group address(es):
FF02::1
FF02::2
FF02::1:FF64:0
MTU is 1500 bytes
ICMP error messages limited to one every 100 milliseconds
ICMP redirects are enabled
ND DAD is enabled, number of DAD attempts: 1
ND reachable time is 30000 milliseconds
ND advertised reachable time is 0 milliseconds
ND advertised retransmit interval is 0 milliseconds
ND router advertisements are sent every 200 seconds
ND router advertisements live for 1800 seconds
Hosts use stateless autoconfig for addresses.

R1#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

R1#

[Flavio Miranda]

Hi @danielseijas3010

Do you have the command "ipv6 nd autoconfig default-router" ?

-If I helped you somehow, please, rate it as useful.-

[danielseijas3010]

The command does not exist in interface configuration mode at least in this version of IOS: 3600 Software (C3640-IK9O3S-M), Version 12.4(13)

The only similar command I could find was: "ipv6 address autoconfig default" which is an extension of the already entered "ipv6 address autoconfig" command, this is what it means as per the ? help:

R1(config-if)#ipv6 address autoconfig ?
default Insert default route

I applied the command above on both routers (in int fa0/0) and it still doesn't work

[Meheretab Mengistu]

Hi,

Try the command 'ipv6 nd route-owner' on global configuration, and run 'ipv6 address autoconfig default' on interface level. I am not sure whether you could run the above command in your version though.

HTH,
Meheretab

[Georg Pauwen]

I labbed this in GNS3, and it does install the default route:

interface FastEthernet0/0
ipv6 address autoconfig default
ipv6 enable

R1#sh ipv6 route

S ::/0 [1/0]
via FE80::CE02:FFF:FE74:0, FastEthernet0/0

[DRUK]

Hi Georg,

I know it's an old post, forgive me please. However, for the purpose of validation of your screen copy here it looks like a STATIC route (S) and not a discovered route. You should actually see something like this *if* the route was learned from autoconfig process I think. Certainly on my debug it is as follows:

ND ::/0 [2/0]
via FE80::A8BB:CCFF:FE80:900, Ethernet0/0

[danielseijas3010 · Accepted solution]

I got it solved, I was simply missing the "ipv6 unicast-routing" global command from R1

Thanks!

[danielseijas3010]

I got it solved, I was simply missing the "ipv6 unicast-routing" global command from R1

FYI, the command suggested does not exist in my version of IOS:

R1#show ver
Cisco IOS Software, 3600 Software (C3640-IK9O3S-M), Version 12.4(13), RELEASE SOFTWARE (fc1)

[Harold Ritter]

You need to configure this command only on router1, which is the router that will install the default to router2. Router 2 should be configured with a /64 and will act as a default router to router 1.

You also want to configure "ipv6 nd ra suppress all" on router 1, so it doesn't send router advertisement to router2, since router 2 is the default router on this subnet.

Regards,