Client DHCPv6 configuration of the router

[cosimodagostino]

Hello everyone I have made several attempts and noticed that after configuring a router as slaac with stateless and configuring the "ipv6 address autoconfig" command on another router (client) without using the "ipv6 enable" command, the router (client) succeeds the link local address is calculated the same. At this point the question arises: When should I use the "ipv6 enable" command if even using only the "ipv6 address autoconfig" command I needed to enable the interface to ipv6 and get the LLA address?

[Georg Pauwen]

Hello,

odd indeed, as, according to all manuals, ipv6 enable is required to transmit IPv6 packets.

When you issue the command:

Device# show ipv6 interface X

with just autoconfig enable, do you see the below line (marked in bold) ?

X is up, line protocol is up
IPv6 is enabled, link-local address is FE80::260:3EFF:FE47:1530
Global unicast address(es):
2001:DB8:C18:1:260:3EFF:FE47:1530, subnet is 2001:DB8:C18:1::/64
MTU is 1500 bytes
ICMP error messages limited to one every 500 milliseconds
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.

[cosimodagostino]

On cisco packet tracer I got two routers. I configured SLAAC with DHCPv6 on "router A". "On router B" I have launched only the command "ipv6 address autoconfig" and the LLA address is calculated for me (I have not launched the "ipv6 enable" command:

Router(config)#int g0/0/0

Router(config-if)#ipv6 address autoconfig

Router(config-if)#exit

Router(config)#do show ipv6 int g0/0/0

""""GigabitEthernet0/0/0 is up, line protocol is up IPv6 is enabled, link-local address is FE80::20C:CFFF:FE62:2D01 No Virtual link-local address(es): Global unicast address(es): 2001:ABCD:ABCD:0:20C:CFFF:FE62:2D01, subnet is 2001:ABCD:ABCD::/64 Joined group address: FF02::1 FF02::2 FF02::1:FF62:2D01 MTU is 1500 bytes ICMP error messages limited to one every 100 milliseconds ICMP redirects are enabled ICMP unreachables are sent ND DAD is enabled, number of DAD attempts: 1 ND reachable time is 30000 milliseconds 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 """"

Among other things, the documentation on the cisco site also says it: "" "" https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_dhcp/configuration/xe-3s /dhcp-xe-3s-book/ip6-dhcp-stateless-xe.html "" "" If you scroll a little you will find: "" "" Configuring the Stateless DHCPv6 Client "" "". It is not written to launch the command "ipv6 enable" but only the command "ipv6 address autoconfig" "" "" This is what I don't understand besides the fact that LLA is generated to me without the "ipv6 enable" command