I am very new to networking and playing around with GNS3. I am trying to configure a router to have 2 IPv6 addresses in a single interface (as far as I understood, this is possible with IPv6)

I managed to add the IPv6 address 2001:CAFE:DEA::25/64 with the following command

R1#config ter
R1(config)#ipv6 unicast-routing
R1(config)#int Ethernet0/0
R1(config-if)#ipv6 address 2001:CAFE:DEA::25/64 

However, immediately afterwards, I try to add another, abbreviated IPv6 address Fe80::1 I just type the command (immediately after typing the last one above)

R1(config-if)#ipv6 address Fe80::1

but I get the error message

Incomplete command 

What am I missing here?

2 Answers 2


You are trying to configure a link-local address without the link-local keyword.

ipv6 address fe80::1 link-local

You're missing the subnet mask.

  • The example routing table im looking at doesn't specify a subnet mask for that one though
    – Dasph
    Jun 3, 2021 at 17:01
  • You can always type a ? to see what command is expected.
    – Ron Trunk
    Jun 3, 2021 at 17:04

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