# How to configure RIPNG on Cisco IOS Router

**URL:** <https://forum.networklessons.com/t/how-to-configure-ripng-on-cisco-ios-router/900>\
**Category:** Lessons Discussion\
**Created:** [December 22, 2016, 12:44am UTC](https://forum.networklessons.com/t/how-to-configure-ripng-on-cisco-ios-router/900 "2016-12-22T00:44:33Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![casper.visser](https://cdn-forum.networklessons.com/letter_avatar_proxy/v4/letter/c/eb9ed0/32.png) [@casper.visser](https://forum.networklessons.com/u/casper.visser)\
**Post date:** [April 8, 2016, 8:59am UTC](https://forum.networklessons.com/t/how-to-configure-ripng-on-cisco-ios-router/900/4 "2016-04-08T08:59:36Z")

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Hi Rene

Just a question, more of a general IPV6 question, why does a loopback interface generate the same link-local address as the physical interface. Yes I understand that the loopback don’t have it’s own mac address and will use the physical interface, but why doesn’t it cause a conflict on the local device, I was under the impression the link-local address must be unique on the llocal device:

```auto
R8#sh ipv6 int brief
Em0/0 [administratively down/down]
    unassigned
GigabitEthernet0/0 [up/up]
    FE80::6273:5CFF:FEF8:D8E0
GigabitEthernet0/1 [up/up]
    unassigned
Serial0/0/0 [down/down]
    unassigned
Loopback0 [up/up]
    FE80::6273:5CFF:FEF8:D8E0
    2001:DB8::1

```

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