# IPv6 OSPFv3 Default Route

**URL:** <https://forum.networklessons.com/t/ipv6-ospfv3-default-route/1536>\
**Category:** Lessons Discussion\
**Created:** [March 2, 2017, 11:34am UTC](https://forum.networklessons.com/t/ipv6-ospfv3-default-route/1536 "2017-03-02T11:34:05Z")\
**Posts on this page:** 1\
**Showing post:** 5

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**Author:** ![ReneMolenaar](https://cdn-forum.networklessons.com/user_avatar/forum.networklessons.com/renemolenaar/32/488_2.png) [@ReneMolenaar](https://forum.networklessons.com/u/ReneMolenaar)\
**Post date:** [July 13, 2018, 2:01pm UTC](https://forum.networklessons.com/t/ipv6-ospfv3-default-route/1536/5 "2018-07-13T14:01:33Z")

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Hi Vinod,

Good question, I never really noticed it before. The answer is in the RFC:

> **[RFC 5340: OSPF for IPv6 | RFC Editor](https://datatracker.ietf.org/doc/html/rfc5340)**
>
> This document describes the modifications to OSPF to support version 6 of the Internet Protocol (IPv6). The fundamental mechanisms of OSPF (flooding, Designated Router (DR) election, area support, Short Path First (SPF) calculations, etc.) remain...

> Inclusion of a forwarding address or external route tag in AS-external-LSAs is now optional. In addition, AS-external-LSAs can now reference another LSA, for inclusion of additional route attributes that are outside the scope of the OSPF protocol. For example, this reference could be used to attach BGP path attributes to external routes.

> The external route tag is present in the AS-external-LSA if and only if the AS-external-LSA’s bit T is set.

Seems they decided to add a route tag by default for OSPFv3 external routes. We use these tags in redistribution:

[https://networklessons.com/cisco/ccie-enterprise-infrastructurehow-to-configure-route-tagging/](https://networklessons.com/cisco/ccie-enterprise-infrastructurehow-to-configure-route-tagging/)

Rene

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