RFC 4577, "OSPF as the Provider/Customer Edge Protocol for BGP/MPLS IP Virtual Private Networks (VPNs)", June 2006

Errata ID: 4659
Status: Held for Document Update
Type: Technical
Publication Format(s) : TEXT
Reported By: Chao Fu
Date Reported: 2016-04-08
Held for Document Update by: Martin Vigoureux
Date Held: 2018-05-22

Section 4.1.4 says:

   If a PE attaches to a CE via a link that is in a non-zero area, then
   the PE serves as an ABR for that area.

It should say:

   PE always serves as an ABR if it attaches to a CE.

Notes:

Even the PE attaches to a CE via a link that is in backbone area, it should also be thought as an ABR. Otherwise the CE cannot calculate the type 3 LSAs from PE because there is no ABR.

Section 4.2.3 has the similar description and should also be updated:
"If a PE has a link that belongs to a non-zero area, the PE functions
as an Area Border Router (ABR) for that area."

--VERIFIER'S NOTES--
After discussing with authors, a more preferred revision of the text could be:
Since OSPF VPN-IPv4 routes are advertised as inter-area summary (type 3) LSAs, a PE will act as an ABR for attached CEs.

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